CONTENTS
CONTENTS
S.NO
CONTENTS
1.
SYNOPSIS
2.
INTRODUCTION
3.
COMPONENTS AND DESCRIPTION
4.
WORKING PRINCIPLE
5.
PIN DIAGRAM
6. DESIGN 7.
ADVA ADVANTAGE AND DIS DI S ADVANTAGE
8.
APPLICATION LIST OF MATERIALS
9.
COST ESTIMATION
1. CONCLUSION 11. 11. !I!LOGRAP"Y 12. P"OTOGRAP"Y
PAGE NO
SYNOPSIS
SYNOPSIS This project is developed for the users to rotate the back wheel of a two wheeler using propeller shaft. Usually in two wheelers, chain and sprocket method is used to drive the back wheel. But in this project, the Engine is connected at the front part of the vehicle. The shaft of the engine is connected with a long rod. The other side of the long rod is connected connected with a set of bevel gears. The bevel gears are used to rotate the shaft in 9 o angle. The back wheel of the vehicle is connected with the bevel gear!driven". Thus the back wheel is rotated in perpendicular to the engine shaft. Thus the two wheeler will move forward. #ccording to the direction of motion of the engine, the wheel will be moved forward or reverse. This avoid the usage of chain and sprocket method
INTRODUCTION
INTRODUCTION
1.1 !#$%$&' I()*+,-%
$ndustry scenario •
% major manufacturers& 'ero, T$($, T$( $, #tlas and #von
•
$ndustry capacity& ))9 lacs cycles cycle s p.a. !as on *%"
•
$ndustry capacity utili+ation& 9- !as on *%"
•
$ndustry penetration& %- !as on *%"
COMPANY
VOLUME LAC NO./
MARKET S"ARE 0/
'E/0
1.
%
T$
*.1
*%
#T2#3
*.1
*%
0T'E/3
4.5
5 Table ).)!a"
$ndia is the second largest maker of bicycles in the world. #round 9 million bicycles !valued ! valued at /s. ) crore" are produced each year. 2udhiana has been the primary source of components for the cycle industry in $ndia. /ecently, 6endor bases have come up in other parts of the country thereby diluting the geographical risk.
7ig ).)!a" •
The $ndian bicycle market comprises of * segments namely +,()-)+ and +'$#&+. 3tandards are the workhorses of rural economy as these are cheap and rugged bicycles. The specials or fancy segment comprises new generation which are more e8pensive.
Table ).)!c" (#/& (ompound #nnual #nnual rowth /ate 32/& sports light roadster :TB& mountain terrain bikes $n last 5 years, specials have posted a higher (#/ on the back of product innovations and pricing.
The domestic demand in $ndia for the cycles majorly comes from rural areas. $n $ndia more than 5 percent of population resides in rura l areas which are a re characteri+ed by poor infrastructural facilities and low income groups. These areas lack the concrete concrete roads and the dirt roads often get damaged during monsoons. Therefore, the rural population demand bicycle more than motor driven vehicles. $n rural area bicycle is one of the most important modes of transportation for middle and low income groups.
7ig ).)!b" T-',+ , ,' #()*+,-%
;ith advent of to )cc segment of motorbikes and increase in people
purchasing power has profoundly hit the cycle manufacturing. •
Emerging Economies are becoming volume drivers with their associated costs, =uality and productivity advantages.
•
>evelopment to global standards in a compressed lead time.
•
$mports pose price based competition in the replacement market.
•
3olution for high volume and world class =uality at low costs.
•
The presence of a large counterfeit components market poses a significant threat.
•
7urther marginali+ation of smaller players likely. •
2ike in many other sectors, the (hinese threat seems to have been
overstated in the cycle industry.
1.2 !#$%$&' •
# bicycle, often called a bike, is a human&powered, pedal&dr iven, iven, single& track vehicle, having two w he els attached attached to a f r ame, a me, one behind the other.
•
Bicycles were introduced in the )9th century in Europe and, as of *1, number more than a billion worldwide, twice as many as automobiles. They are the princi princ ipal means of transportation in many regions. They also provide a popular form of recreation, and have been adapted for use as children?s children?s toys, general fitness, fitness, military and police applications, applications, courier services, and bicycle racing.
•
The basic shape and configuration of a typical upright, or safety bicycle, has changed little since the first chain&driven model was developed around ). But many details have been improved, especially since the advent of modern material materials and computer&aided design. These have allowed for a proliferation of speciali+ed designs for many types t ypes of cycling.
•
The bicycle?s bicycle?s invent invention ion has had an enormo enormous us effect effect on society society,, both both in terms of culture culture and of advancing advancing modern industrial industrial methods. methods. 3everal
components that eventually played a key role in the development of the automobile were initially invented for use in the bicycle, including ball bearings, pneumatic tires, chain& driven driven sprockets, and tension&s poked wheels. 1.2.1 "#+,-%
7ig ).*!a"
1. INTR INTROD ODUC UCTI TION ON
# shaft&driv shaft&driven en bicycle bicycle is a bicycle bicycle that that uses a drive shaft instead shaft instead of a chain chain to to transmit transmit power from the pedals to the wheel. 3haft drives were introduced over over a century ago, but were mostly supplanted by chain&driven bicycles due to the gear ranges possible with sprockets and derailleur. /ecently, due to advancements in internal gear technology, a small number of modern shaft&driven bicycles bic ycles have been introduced.
3haft&d 3haft&driv riven en bikes bikes have have a large large bevel bevel gear gear whe where re a conven conventio tional nal bike bike would would have have its chain ring. ring. This meshes with another bevel gear mounted mounted on the drive shaft. The use of bevel gears allows the a8is of the drive tor=ue from the pedals to be turned through 9 degrees. The drive shaft then has another bevel gear near the rear wheel hub which
meshes with a bevel gear on the hub where the rear sprocket would be on a conventional bike, and canceling out the first drive tor=ue tor=ue change of a8is.
7ig.).)
#n automotive drive shaft transmits power from the engine to the differential gear of a rear wheel drive vehicle. The drive shaft is usually manufactured in two pieces to increa increase se the fundam fundamenta entall bendin bending g natura naturall fre=uen fre=uency cy becaus becausee the bendin bending g natura naturall fre= fre=ue uency ncy of a shaf shaftt is inve inverse rsely ly prop propor ortio tiona nall to the the s=ua s=uare re of beam beam leng length th and and proportional to the s=uare root of of specific modulus which increases the total weight of an automo automotiv tivee vehicle vehicle and decreases decreases fuel fuel efficie efficiency ncy.. 3o, a single single piece piece drive drive shaft shaft is preferred here and the material of it is considered to be Titanium alloy because of its high strength and low density. >rive shafts are carriers of tor=ue and are subject to torsion and shear stress, e=uivalent to the difference between the input tor=ue and the load. They must therefore be strong enough to bear the stress, whilst avoiding too much additional weight as that would in turn increase their inertia. @arker 'annifin 'annifin is a motion motion and control technologies technologies corporationA corporationA in * they started the (hainless (hallenge, it is a competition that was inspired by the cycling ity 3in lar rtio of @arker< @arker< busine busine foc hydrau hydraulics lics the
decided to merge the two ideas into a competition. This competition rules are fairly simple develop a )- human powered bicycle without using any chains to transfer power. This competition was primarily aimed towards students of universities as a senior design project. Each university chosen to compete selects a group of & seniors to participate. These students start from scratch and design either a hydraulically or pneumatically powered bike to compete in several different races. There was an endurance endurance race, an efficiency efficiency race, and a sprint sprint race. The endurance endurance race was an mile course. The efficiency race deals with utili+ing an accumulator to store energy for a later use. The sprint race was ) meter dash to the finish. Each team needs to work together to create a bike that works the best in each race in order to win the (hainless (hallenge. This year
1.1 P*-+' ,' D-#' S, O- P-'&&'- S,/ The tor=ue that is produced from the engine and transmission must be transferred to the rear wheels to push the vehicle forward and reverse. The drive shaft must provide a smooth, smooth, uninterrupted uninterrupted flow of power to the a8les. The drive shaft and differential differential are used to transfer this tor=ue.
1.2 F*($,#(+ ,' D-#' S, a" 7irst, it must transmit transmit tor=ue tor=ue from from the transmi transmission ssion to the the different differential ial gear bo8. bo8. b" >uring the operation, it is necessary to transmit ma8imum low&gear tor=ue developed by the engine. c" The drive drive shafts shafts must also be capable capable of rotating rotating at the the very fast fast speeds speeds re=uired re=uired by the vehicle. d" The drive drive shaft shaft must must also also operat operatee throug through h consta constantly ntly changi changing ng angles angles betwee between n the transmission, the differential and the a8les. #s the rear wheels roll over bumps in the road, the differential and a8les move up and down. This movement changes the angle between the transmission and the differential. e" The length length of the the drive drive shaft must must also be be capable capable of changing changing while while transmitti transmitting ng tor=ue. 2ength changes are caused by a8le movement due to tor=ue reaction, road deflections, braking loads and so on. # slip joint is used to compensate for this motion. The slip joint is usually made of an internal and e8ternal spline. $t is located on the front end of the drive shaft and is connected to the transmission. ow days all automobiles !which are having front engine rear wheel drive" have the transmission transmission shaft as shown in figure. # pair of short drive shafts is commonly used to send power from a central differential, transmission, or transa8le to the wheels. Two piece drive shaft increases the weight of drive shaft which is not desirable in today
systems and these methods based on mathematical programming techni=ues involving gradie gradient nt search search and direct search. search. The The reduct reduction ion in weight weight of the drive drive system system is advantageous in overall weight reduction of automobiles which is a highly desirable goal of design engineer.
7ig.).*!a" 1> model of a drive shaft
7ig.).*!b"
@osition of >rive 3haft
2. LITERATURE REVIEW 2.1 I(,-)*$,#( >rive shafts are carriers of tor=ueA they are subject to torsion and shear stress, which represents the difference between the input force and the load. They thus need to be strong enough to bear the stress, s tress, without imposing too great an additional inertia by virtue of the weight of the shaft. :ost automobiles today use rigid driveshaft to deliver power from a transmission to the wheels. # pair pair of short driveshaft drives haft is commonly used to send power from a central differential, transmission, or transa8ie to the wheels. There are different types of drive shafts in #utomotive $ndustryC a" ) pie piece ce driv drives esha haft ft b" * piece driveshaft c" 3lip 3lip in in Tub Tubee driv drivesh eshaf aftt
The The 3lip 3lip in Tube ube >riv >rives esha haft ft is the the new new type type whic which h also also help helpss in (rash (rash Energy Energy :anagement. $t can be compressed in case of crash. $t is also known as a collapsible drive shaft. 7ront&wheel drive is the most common form of engineDtransmission layout used in modern passenger cars, where the engine drives the front wheels. :ost front wheel drive vehicles today feature transverse engine mounting, where as in past decades engine enginess were were mostly mostly positi positione oned d longit longitudi udinal nally ly instead instead.. /ear&w /ear&whee heell drive drive was the traditional standard and is still widely used in lu8ury cars and most sport cars.
2.2 "#+,-% The first shaft drives drives for cycles appear to have been invented independent independently ly in )9 in the United 3tates and England. England. #. 7earnhead, 7earnhead, of 1% (aledonian (aledonian /oad, orth 2ondon 2ondon developed one in )9 and received a patent in 0ctober )9).'is prototype shaft was enclos enclosed ed within within a tube tube runnin running g along along the top of the chainstay chainstayAA later later model modelss were were enclosed within the actual chainstay.$n the United United 3tates, ;alter 3tillman filed for a patent on a shaft&driven bicycle on >ec. ), ), )9 which was was granted on uly *), )9). )9). The shaft drive was not well accepted in England, so in )9% 7earn head took it to the U3# where where (olo (olonel nel @ope of the (olum (olumbia bia firm boug bought ht the e8clusive #merican #merican rights. Belatedly, the English makers took it up, with 'umber in in particular plunging heavily on the deal. (uriously enough, the greatest of all the 6ictorian cycle engineers, @rofessor #rchib #rc hibald ald 3ha 3harp, rp, was aga agains instt sha shaft ft dri driveA veA in his cla classic ssic )9 )95 5 bo book ok FBi FBicy cycles cles and TricyclesF, he writes FThe 7earn head ear.... if bevel&wheels could be accurately and cheaply cut by machinery, it is possible that gears of this description might supplant, to a great e8tent, the chain&drive chain&drive gearA but the fact that the teeth of the bevel&wheels bevel&wheels cannot be accurately milled is a serious obstacle to their practical successF.
$n the U3#, they had been made by the 2eague (ycle (ompany as early as )91. G%H 3oon after, the 7rench company :etropole marketed their #catane. By )94 (olumbia began aggressively to market the chainless bicycle it had ac=uired from the 2eague (ycle (ompany. (hainless bicycles were moderately popular in )9 and )99, although sales were still much smaller than regular bicycles, primarily due to the high cost. The bikes were also somewhat less efficient than regular bicyclesC there was roughly an percent loss in the gearing, in part due to limited manufacturing technology at the time. The rear wheel was also more difficult to remove to change flats. :any of these deficiencies have been overcome in the past century. century.
$n )9*, )9*, The The 'ill&( 'ill&(lim limber ber Bicycl Bicyclee :fg. :fg. (ompan (ompany y sold sold a three&s three&spee peed d shaft&d shaft&driv riven en GH bicycle in which the shifting was implemented with three sets of bevel gears. ;hile a small small number number of chainl chainless ess bicycl bicycles es were were availab available, le, for the most most part, part, shaft&d shaft&driv riven en bicycles disappeared from view for most of the *th century. There is, however, still a niche market for chainless bikes, chainless bikes, especially for commuters, and there are a number of manu manufa fact ctur urer erss who who offe offerr them them eith either er as part part of a larg larger er rang rangee or as a prim primar ary y speciali+ation. # notable notable e8ample is Bio mega in mega in >enmark.
WORKING PRINCIPLE
!LOCK DIAGRAM
COMPONENTS AND DESCRIPTION
COMPONENTS AND DESCRIPTION
D#'-'(, T%'+ T%'+ S,+ T-(+#++#( +, These shafts transmit power between the source and the ). T-(+#++#( machines machines absorbing absorbing power. The counter shafts, line shafts, shafts, overhead overhead shafts shafts and all factory shafts are transmission transmission shafts. shafts. 3ince these shafts carry machine machine parts such as pulleys, gears etc., therefore they are subjected to bending moments in addition to twisting. *. M$#(' S, These shafts form an integral part of the machine itself. 7or e8am e8ampl ple, e, the the cran cranks ksha haft ft is an inte integr gral al part part of $.(. $.(.en engi gine ness slid slider er&c &cra rank nk mechanism. 1. A&' # shaft is called Ian a8leJ, if it is a stationary machine element and is used for the transmission of bending moment only. $t simply acts as a support for rotating bodies. A&#$,#( To support hoisting drum, a car wheel or a rope sheave. %. S#()&' # shaft is called called Ia spindleJ spindleJ,, if it is a short short shaft that that imparts imparts motion motion either to a cutting tool or to a work&piece. A&#$,#(+ ). >rill press spindles&impart motion to cutting tool !i.e." drill. *. 2athe spindles&impart motion to work&piece.
#part from, an a8le and a spindle, shafts are used at so many places and almost everywhere wherever power transmission is re=uired. 7ew of them areC ). A*,:#&' D-#' S, Transmits power from main gearbo8 to differential gear bo8. *. S# P-'&&'- S, Transmits power from gearbo8 to propeller attached on it. 1. "'&#$,'- T#& R,- S, Transmits power to rail rotor fan.
P-, D-#' S,
7igure.).1
2.4 D''-#,+ C('(,#(& D-#' S, ). They have less specific modulus and strength. *. $ncreased weight. 1. (onventional steel drive shafts are usually manufactured in two pieces to increase the fundamental bending natural fre=uency because the bending natural fre=uency of a shaft is inversely proportional to the s=uare of beam length and proportional to the s=uare root of specific modulus. Therefore the steel drive shaft is made in two sections connected by a support structure, bearings and U&joints and hence over all weight of assembly will be more. %. $ts corrosion resistance is less as compared with composite materials. . 3teel drive shafts have less damping capacity.
2.5 M'-#,+ C+#,' D-#' S, ). They have high specific specific modulu moduluss and and strengt strength. h. *. /edu /educe ced d weig weight ht.. 1. The fundamen fundamental tal natural natural fre=uency fre=uency of the the carbon fiber fiber composite composite drive drive shaft shaft can be twice as high as that of steel or alluminium because the carbon fiber composite material has more than % times the specific stiffness of steel or alluminium, which makes it possible to manufacture the drive shaft of passenger cars in one piece. # one&piece composite shaft can be manufactured so as to satisfy the vibration re=uirements. This eliminates all the assembly, connecting the two piece steel shafts and thus minimi+es the overall weight, vibrations and the total cost %. >ue to the weight weight reduct reduction, ion, fuel fuel consumpt consumption ion will will be reduced reduced.. . They have have high dampin damping g capacity hence they they produce produce less vibration vibration and and noise. 5. They They have have good good corros corrosion ion resista resistance nce.. 4. reater tor=ue tor=ue capacity capacity than steel or allumin alluminium ium shaft. . 2onger 2onger fatigue fatigue life than than steel or allumin alluminium ium shaft. 9. 2ower rotating rotating weight weight transmits transmits more more of available available power power..
2.6 D-#' S, V#:-,#( 6ibration 6ibration is the most common drive shaft problem. 3mall cars and short vans and trucks !2:6" are able to use a single drive shaft with a slip s lip joint at the front end without e8periencing any undue vibration. 'owever, with vehicles of longer wheel base, the longer drive shaft re=uired would tend to sag and under certain operating conditions would tend to whirl and then setup resonant vibrations in the body of the vehicle, which will cause the body to vibrate as the shaft whirls.
6ibration can be either transverse or torsional. Transverse vibration is the result of unbalanced condition acting on the shaft. This condition is usually by dirt or foreign material on the shaft, and it can cause a rather noticeable vibration in the vehicle. Torsional vibration occurs from the power impulses of the engine or from improper univ univer ersal sal join join angl angles. es. $t caus causes es a noti notice ceab able le soun sound d dist distur urba banc ncee and and can can caus causee a mechanical shaking. $n e8cess, both types of vibration can cause damage to the universal joints and bearings. ;hirling of a rotating shaft happens when the centre of gravity of the shaft mass is eccentric and so is acted upon by a centrifugal force which tends to bend or bow the shaft so that it orbits about the shaft longitudinal a8is like a rotating skipping rope. #s the speed rises, the eccentric deflection of the shaft increases, with the result that the centrifugal force also will increase. The effect is therefore cumulative and will continue until the whirling become critical, at which point the shaft will vibrate violently. 7rom the theory of whirling, it has been found that the critical whirling speed of the shaft is inversely inversely proportional proportional to the s=uare s=uare of the shaft length. length. $f, therefore, therefore, a shaft having, for e8ample, a critical whirling speed of 5 revDmin is doubled in length, the critical whirling of the new shaft will be reduced to a =uarter of this, i.e. the shaft will now begin to rotate at ) revDmin. The vibration problem could solve by increasing the diameter of the shaft, but this would increase its strength beyond its tor=ue carrying re=uirements and at the same time increase its inertia, which would oppose the vehicle
3. DRIVE MEC"ANISM 3.1 I(,-)*$,#( 7or the gear&like device used to drive a roller chain, see 3procket 3procket.. This article is about mecha mechani nical cal gears gears.. 7or 7or othe otherr uses, uses, see see ear !disam !disambigua biguation" tion"Tw Two o mes meshin hing g gea gears rs transmitting rotational motion. ote that the smaller gear is rotating faster. #lthough the larger larg er gear is rotatin rotating g less =uickly, =uickly, its tor=u tor=uee is prop proportio ortionally nally greater. greater. 0ne subtl subtlety ety of this particular arrangement is that the linear speed at the pitch diameter is the same on both gears.
# ;'- or $;<''& is a rotating machine part having cut teeth or cogs teeth,, cogs,, which mesh mesh with with another toothed part in order to transmit tor=ue tor=ue,, in most cases with teeth on the one gear being of identical shape, s hape, and often also with that shape on the other gear. Two or more gears working in tandem are called a transmission transmission and and can produ produce ce a mechanical mechanical advantage advantage thr throug ough h a gear gear ratio ratio an and d th thus us ma may y be co cons nsid ider ered ed a simple machine. machine. eared devices can change the speed, tor=ue, and direction of a
The most common situation is for a gear to mesh with another gearA however, a gear can also mesh with a non&rotating toothed part, called a rack, thereby producing translation instead translation instead of rotation.
The gears in a transmission are analogous to the wheels in a crossed belt pulley system. #n advantage of gears is that the teeth of a gear prevent slippage. ;hen two gears mesh, and one gear is bigger than the other !even though the si+e of the teeth must match", a mechanical advantage is produced, with the rotational speeds and speeds and the tor=ues of the two gears differing in an inverse relationship. $n transmissions which offer multiple gear ratios, such as bicycles, motorcycles, and cars, the term ;'-, as in first in first gear , refers to a gear ratio rather than an actual physical gear ge ar.. Th Thee te term rm is us used ed to de desc scri ribe be si simi mila larr de devi vice cess ev even en wh when en th thee ge gear ar ra rati tio o is continuous rather continuous rather than discrete, discrete, or when the device does not actually contain any gears, as in a continuously variable transmission. transmission. The earliest known reference to gears was circ rcaa #.>. by 'ero 'ero of #le8a le8and ndri riaa, but they can be tra racced back to the reek mechanics mechanics of the #le8andrian school in school in the 1rd century B.(. and were greatly devel elo oped by the reek polymath #rchimedes !* !*4K* 4K*)* )* B.( B.(.". .". Th Thee #ntikythera mechanism is an e8a e8ampl mplee of a ver very y ear early ly and intricate intricate gea geared red dev device, ice, designed designed to calculate astronomical positions. astronomical positions. $ts time of construction is now estimated between ) and ) B(. The definite velocity ratio which results from having teeth gives gears an advantage over other drives !such as traction drives traction drives and 6&belts" 6&belts" in precis precision ion machines machines such as watches that th at de depe pend nd up upon on an e8 e8act act ve velo locit city y rat ratio io.. $n ca cases ses wh wher eree dr driv iver er an and d fo foll llow ower er ar aree pro8imal, gears also have an advantage over other drives in the reduced number of parts re=uir re= uiredA edA the dow downsi nside de is tha thatt gea gears rs are mo more re e8p e8pens ensive ive to man manufa ufactu cture re and their lubrication re=uirements may impose a higher operating cost.
3.2 Types 3.2.1 External gear #n e8ternal gear is one with the teeth formed on the outer surface of a cylinder or cone. (onversely, 3.2.2 I(,'-(& ;'-
an internal internal gear is one with the teeth formed on the inner surface of a cylin c ylinder der or cone. 7or bevel 7or bevel gears, gears, an internal gear is one with the pitch the pitch angle e8ceeding 9 degrees. $nternal gears do not cause output shaft direction reversal.
3.2.3 L#+, ;'-+ S*- ;'-
3pur gears or straight&cut gears are the simplest type of gear. They consist of a cylinder or disk with the teeth projecting radials, and although they are not straight&sided in form !they are usually of special form to achieve constant drive ratio, mainly involute", involute", the edge of each tooth is straight and aligned parallel to the a8is of rotation. These gears can be meshed together correctly only if they are fitted to parallel parallel shafts. "'&#$& ;'-+ 'elical or Fdry fi8edF gears offer a refinement over spur gears. The leading edges of the teeth are not parallel to the a8is of rotation, but are set at an angle. 3ince the gear is curved, this angling causes the tooth shape to be a segment of a heli8. heli8. 'elical gears can be meshed unparallel or crossed orientations. The former refers to when the shafts are parallel to each otherA this is the most common orientation. $n the latter, the shafts are non¶llel, and in this configuration the gears are sometimes known as Fskew gearsF. The angled teeth engage more gradually than do spur gear teeth, causing them to run more smoothly and =uietly. ;ith parallel helical gears, each pair of teeth first make contact at a single point at one side of the gear wheelA a moving curve of contact then grows gradually across the tooth face to a ma8imum then recedes until the teeth break contact at a single point on the opposite side. $n skew gears, teeth suddenly meet at a line cont co ntact act acr acros osss th thei eirr en enti tire re wi widt dth h ca caus usin ing g str stres esss an and d no noise ise.. 3k 3kew ew ge gears ars ma make ke a chara ch aract cteri erist stic ic wh whin inee at hi high gh sp speed eeds. s. ;h ;here ereas as sp spur ur ge gears ars ar aree us used ed fo forr lo low w sp speed eed applications and those situations where noise control is not a problem, the use of helical gears is indicated when the application involves high speeds, large power transmission, or where noise abatement is abatement is important. The speed is considered to be high when the pitch line velocity e8ceeds * mDs. # disadvantage of helical gears is a resultant thrust along thrust along the a8is of the gear, which needs to be accommodated by appropriate thrust bearings, bearings, and a greater degree of sliding friction between friction between the meshing teeth, often addressed with additives in the lubricant.
Skew gears 7or a ?crossed? or ?skew? configuration, the gears must have the same pressure angle and normal pitchA however, the heli8 angle and handedness can be different. The relationship between the two shafts is actually defined by b y the heli8 angle!s" of the two shafts and the handedness, as definedC ;here is the heli8 angle for the gearL The crossed configuration is less mechanically sound because there is only a point contact between the gears, whereas in the parallel configuration there is a line contact.
Muite commonly, helical gears are used with the heli8 angle of one having the negative of the heli8 angle of the otherA such a pair might also be referred to as having a right& handed heli8 and a left&handed heli8 of e=ual angles. The two e=ual but opposite angles add to +eroC the angle between shafts is +ero K that is, the shafts are parallel. ;here ;here the sum or the difference !as described in the e=uations above" is not +ero the shafts are crossed. 7or shafts crossed at right angles, the heli8 angles are of the same hand because they must add to 9 degrees. D*:&' '&#$& ;'-+
>ouble hel >ouble helical ical gea gears, rs, or herringbon herringbonee gears, gears, ov overc ercom omee th thee pr prob oblem lem of a8 a8ia iall th thru rust st presented by FsingleF helical gears, by having two sets of teeth that are set in a 6 shape. # double helical gear can be thought of as two mirrored helical gears joined together. This arrangement cancels out the net a8ial thrust, since each half of the gear thrusts in the opposite direction resulting in a net ne t a8ial force of +ero. This arrangement can remove the nee need d for thr thrust ust bea bearin rings. gs. 'o 'owev wever er,, dou double ble hel helical ical gea gears rs are mor moree dif diffic ficult ult to manufacture due to their more complicated shape. 7or both possible rotational directions, there e8ist two possible arrangements for the oppositely&oriented helical gears or gear faces. 0ne arrangement is stable, and the other is unstable. $n a stable orientation, the helical gear faces are oriented so that each a8ial force is directed toward the center of the gear. $n an unstable orientation, both a8ial forces are directed away from the center of the gear. $n both arrangements, the total !or net" a8ial force on each gear is +ero when the gears are aligned correctly. $f the gears become misaligned in the a8ial direction, the unstable arrangement will generate a net force that may lead to disassembly of the gear train, while the stable arrangement generates a net corrective force. $f the direction of rotation is reversed, the direction of the a8ial thrusts is also reversed, so a stable configuration becomes unstable, and vice versa. 3table double helical gears can be directly interchanged with spur gears without any need for different bearings. !''& ;'-
# bevel gear is shaped like a right circular cone with cone with most of its tip cut off. ;hen two bevel gears mesh, their imaginary i maginary vertices must occupy the same point. Their shaft a8es also intersect at this point, forming an arbitrary non&straight angle between the shafts. The angle between the shafts can be anything e8cept +ero or ) degrees. Bevel gears with e=ual numbers of teeth and shaft a8es at 9 degrees are called miter gears.
Spiral bevels 3piral bevel gears can be manufactured as leason types !circular arc with non&constant tooth too th dep depth" th" 0er 0erlik likon on and (ur (urve8 ve8 typ types es !ci !circul rcular ar arc wit with h con constan stantt too tooth th dep depth" th"
Nlingel eln nberg(ycl clo o&@ &@aalloid !Ep !E picy cyccloids with const staant tooth depth" or Nlingelnberg@alloid. 3piral bevel gears have the same advantages and disadvantages relative to their straight&cut cousins as helical gears do to spur gears. 3traight bevel gears are generally used only at speeds below mDs !) ftDmin", or, for small gears, ) rpm. oteC The cylindrical gear tooth profile corresponds to an involute, but the bevel gear toot to oth h pr prof ofil ilee to an oc octo toid id.. #ll tr trad adit itio iona nall be beve vell ge gear ar ge gene nerat rator orss !l !like ike l lea easo son, n, Nlingelnberg, 'eidenreichO'arbeck, and ;:;:odule" manufacture bevel gears with an octoidal tooth profile. $:@0/T#TC 7or &a8is milled bevel gear sets it is important to choose the same calculation D layout like the conventional manufacturing method. 3implified calculated bevel gears on the basis of an e=uivalent cylindrical gear in normal section with an involute tooth form show a deviant tooth form with reduced tooth strength streng th by )&* )&*- witho without ut offs offset et and %- with offset G>iss. 'Pne 'Pnecke, cke, TU >resd >resdenH. enH. 7urthermore those Finvolute bevel gear setsF causes more noise. "%#) ;'-
'ypoid gears resemble spiral bevel gears e8cept the shaft a8es do not intersect. The pitch surfaces appear conical but, to compensate for the offset shaft, are in fact hyperboloids o hyperboloids off rev revolu olutio tion. n. 'y 'ypoi poid d gea gears rs are alm almost ost alw alway ayss des design igned ed to ope operat ratee with shafts at 9 degrees. >epending on which side the shaft is offset to, relative to the angling of the teeth, contact between hypoid gear teeth may be even smoother and more gradual than with spiral bevel gear teeth, but also have a sliding action along the meshing teeth as it rotates and therefore usually re=uire some of the most viscous types of gear oil to avoid it being e8truded from the mating tooth faces, the oil is normally designated '@ !for hypoid" followed by a number denoting the viscosity. #lso, the pinion the pinion can can be designed with fewer teeth than a spiral bevel pinion, with the result that gear ratios of 5C) and higher are feasib feasible le using a singl singlee set of hypoid gears gears . This style of gear is most commonly found driving mechanical differentialsA which are normally straight cut bevel gearsA in motor vehicle a8les.
3.3 Backlash Backlash is the error in motion that occurs when gears change direction. $t e8ists Backlash because there ther e is always some gap between the trailing trai ling face of the driving tooth and the leading face of the tooth behind it on the driven gear, and that gap must be closed before force can be transferred in the new direction. The term FbacklashF can also be used to refer to the si+e of the gap, not just the phenomenon it causesA thus, one could speak of a pair of gears as having, for e8ample, F.) mm of backlash.F # pair of gears could be designed to have +ero backlash, but this would presuppose perfection in manufacturing, uniform uniform thermal thermal e8pansion e8pansion characteristic characteristicss throughou throughoutt the system, system, and no lubricant. lubricant. Therefore, gear pairs are designed to have some backlash. $t is usually provided by reducing the tooth thickness of each gear by half the desired gap distance. $n the case of a large gear and a small pinion, however, the backlash is usually taken entirely off the
gear and the pinion is given full si+ed teeth. Backlash can also be provided by moving the gears further apart. The backlash of a gear train e=uals the sum of the backlash of each pair of gears, so in long trains backlash can become a problem.
7or situations in which precision is important, such as instrumentation and control, backlash can be minimi+ed through one of several techni=ues. 7or instance, the gear can ca n be split along a plane perpendicular to the a8is, one half fi8ed to the shaft in the usual manner, the other half placed alongside it, free to rotate about the shaft, but with springs between the two halves providing relative tor=ue between them, so that one achieves, in effect, a single gear with e8panding teeth. #nother method involves tapering the teeth in the a8ial direction and providing providing for the gear to be slid in the a8ial direction direction to take up slack.
3.4 Shifting of gears $n some machines !automobiles" it is necessary to alter the gear ratio to suit the task, a process known as gear shifting or changing gear. There are several outcomes of gear shifting in motor vehicles. $n the case of vehicle noise emissions, emissions, there are higher sound levels emitted levels emitted when the vehicle is engaged engaged in lower gears. The design life of the lower ratio gears is shorter, so cheaper gears may be used !i.e. spur for )st and reverse" which tends to generate more noise due to smaller overlap ratio and a lower mesh stiffness etc. than the helical gears used for the high ratios. This fact has been utili+ed in analy+ing vehicle vehicle generated generated sound since the late late )95s, )95s, and has been been incorp incorporat orated ed into into the simulation simulation of urban roadway noise and corresponding corresponding design of urban noise barriers along roadways.
3.5 Tooth Tooth prole p role # profile is one side of a tooth in a cross section between the outside circle and the root circle. Usually a profile is the curve of intersection of a tooth surface and a plane or surface normal to the pitch surface, such as the transverse, normal, or a8ial plane. The fillet curve !root fillet" is the concave portion of the tooth profile where it joins the bottom of the tooth space. The velocity ratio is dependent on the profile of the teeth. 7riction and 7riction and wear between two gears is also dependent on the tooth profile. There are a great many tooth profiles that will give a constant velocity ratio, and in many cases, given an arbitrary tooth shape, it is possible to develop a tooth profile for the mating
profiles have been by far the most commonly commonly used in modern times. They are the cycloid and the involute involute.. The cycloid was more common until the late )sA since then the involute has largely superseded it, particularly in drive train applications. The cycloid is in some ways the more interesting and fle8ible shapeA however the involute has two advantagesC it is easier to manufacture, and it permits the center to center spacing of the gears to vary over some range without ruining the constancy of the velocity ratio. (ycloidal gears only work properly if the center spacing is e8actly right.
3.6 Gear materials umerous nonferrous alloys, cast irons, powder&metallurgy and plastics are used in the manufacture of gears. 'owever, steels are most commonly used because of their high strength&to&weight ratio and low cost. @lastic is commonly used where cost or weight is a concern. # properly designed plastic gear can replace steel in many cases because it has many desirable properties, including dirt tolerance, low speed meshing, the ability to FskipF FskipF =uite =uite well and the ability ability to be made with material materialss not needin needing g additi additiona onall lubrication. :anufacturers have employed plastic gears to reduce costs in consumer items including copy machines, optical storage devices, cheap dynamos, consumer audio e=uipment, servo motors, and printers.
3.7 The module system #s a result, the term module is usually understood to mean the pitch diameter in millimeters divided by the number of teeth. ;hen the module is based upon inch measurement measurements, s, it is known as the English module module to avoid confusion confusion with the metric module. :odule is a direct dimension, whereas diametral pitch is an inverse dimension !like Fthreads per inchF".
4. DESIGN OF CAST IRON DRIVE S"AFT 4.1 I(,-)*$,#( # +,=)-# a bicycle that that uses a drive shaft instead shaft instead of a chain chain to to transm transmit it +,=)-#'( '( :#$%$&' is a bicycle power from the pedals to the wheel through contact of gears and a shaft rod to smoothly and efficient efficient.. 3h 3haft aft dr driv ives es we were re in intr trod oduc uced ed ov over er a ce cent ntury ury ag ago, o, bu butt we were re mo most stly ly supplanted by chain&driven bicycles due to the gear ranges possible with sprockets and
derailleurs. /ecently, derailleurs. /ecently, due to advancements in internal gear technology, a small number of modern shaft&driven bicycles have been introduced.
4.1.1 P*-+' ,' D-#' S, The tor=ue that is produced from the engine and transmission must be transferred to the rear wheels to push the vehicle forward moment. The drive shaft must provide a smooth, uninterrupted flow of power to the a8les. The drive shaft and differential are used to transfer this tor=ue.
4.1.2 F*($,#(+ ,' D-#' S, ). $t must must transmit transmit tor=ue tor=ue from from the transmis transmission sion to the the pedal pedal *. >uring >uring the operatio operation, n, it is necessary necessary to to transmit transmit ma8imum ma8imum low&gear low&gear tor=ue tor=ue 1. The drive drive shafts shafts must also be capable capable of rotating rotating at the the very fast fast speeds speeds re=uired re=uired by the vehicle. %. The drive drive shaft must must also operate operate throug through h constantly constantly changin changing g gear velocity velocity ratio ratio . . The length length of the the drive drive shaft must must also be be capable capable of changing changing while while transmitti transmitting ng tor=ue. 2ength changes are caused by a8le movement due to tor=ue reaction, road deflections, braking loads and so on. # slip joint is used to compensate for this motion. 5. The slip slip joint joint is usually usually made made of an internal internal and e8tern e8ternal al spline. spline. $t is located located on the front end of the drive shaft and is connected to the transmission.
4.2 C(+,-*$,#( () <->#(; -#($#&' The term >rive shaft is used to refer to a shaft, shaft, which is used for the transfer transfer of motion from one point to another. ;hereas the shafts, which propel !push the object ahead" are referred to as the propeller shafts. 'owever the drive shaft of the automobile is also referred to as the propeller shaft because apart from transmitting the rotary motion from the front end to the rear end of the vehicle, these shafts also propel the vehicle forward. The shaft is the primary connection between the front and the rear end !engine and differential", which performs both the jobs of transmitting the motion and propelling the front end. Thus the terms >rive 3haft and @ropeller 3hafts are used interchangeably. $n other words, a drive shaft is a longitudinal power transmitting, used in vehicle where the pedal is situated at the human feet. # drive shaft s haft is an assembly ass embly of one or more tubular shafts connected by universal, constant velocity or fle8ible joints. The number of tubular pieces and joints depends on the distance between between the two wheels. The job involved is the design for suitable propeller shaft and replacement of chain drive smoothly to transmit power from the engine to the wheel without slip. $t needs only a less maintenance. $t is cost effective. @ropeller shaft strength is more and also propeller
with the universal joint is a fle8ible joint. $t turns into any angular position. The both end of the shaft are fitted with the bevel pinion, the bevel pinion engaged with the crown and power is transmitted to the rear wheel through the propeller shaft and gear bo8. . ;ith our shaft drive bikes, there is no more grease on your hands or your clothesA and no more chain and derailleur maintenance. 3haft&driv 3haft&d riven en bik bikes es hav havee a lar large ge bevel bevel gear gear whe where re a con conven ventio tional nal bik bikee wo would uld hav havee its chain ring. ring. This meshes with another bevel gear gear mounted mounted on the drive shaft. The use of bevel gears allows the a8is of the drive tor=ue from the pedals to be turned through 9 degrees. The drive shaft then has another bevel gear near the rear wheel hub which meshes with a bevel gear on the hub where the rear sprocket would be on a conventional bike, and canceling out the first drive tor=ue tor=ue change of a8is. The 9°ree change of the drive plane that occurs at the bottom the bottom bracket bracket and and again at the re rear ar hu hub b us uses es be beve vell ge gear arss fo forr th thee mo most st ef effi ficie cient nt pe perf rform orman ance, ce, th thou ough gh ot othe her r mechanisms could be used, e.g. 'obson
7ig %.).Bevel ear :echanism
4.3 S'$##$,#( )-#' +, The specifications of the composite drive shaft of an automotive transmission are same as that of the steel drive shaft for optimal design. The fundamental natural bending fre=uency for passenger cars, small trucks, and vans of the propeller shaft should be higher than 5, rpm to avoid whirling vibration and the tor=ue transmission capability of the drive shaft should be larger than 1, m. The drive shaft outer diameter should not e8ceed ) mm due to space limitations. 'ere outer diameter of the shaft is taken as 9 mm. The drive shaft of transmission system is to be designed optimally for following specified specifi ed design re=uirements as shown in Table. Table.
T:&' D'+#;( -'?*#-''(,+ () +'$##$,#(+ S.N
N'
N,,#(
U(#,
V&*'
*.
:a8.3peed of shaft
ma8
1.
2ength of 3haft
2
/p /pm
5
:m
)*
3teel !3:%(" used for automotive drive shaft applications. The material properties of the steel !3:%(" are given in Table. The steel drive shaft should satisfy three design specifications such as tor=ue transmission capability, buckling tor=ue capability and bending natural fre=uency. fre=uency. T:&' M'$(#$& -'-,#'+ C+, #-( SM45C/ S.N
M'$.P-'-,#'+
S%:&
U(#,+
C+, I-(
1.
Qoungs :odulus
E
@a
).
2.
3hear :odulus
@a
15.4
3.
@oisson /atio
v
======
.*1
4.
>ensity
R
NgDm1
4*9
5.
Qield 3trength
3y
:@a
)1
6.
3hear 3trength
3s
:@a
)59
4.4 D'+#;( A++*,#(+ ). The shaft rotates at a constant speed about its longitudinal a8is. *. The shaft has a uniform, circular cross section. 1. The shaft is perfectly balanced, i.e., at every cross section, the mass center coincides with the eometric center. %. #ll damping and nonlinear effects are e8cluded. . The The stress& stress&stra strain in relatio relationsh nship ip for compos composite ite materia materiall is linear linear O elastic elasticAA hence, hence, 'ooke
4.5 S'&'$,#( C-++=S'$,#( The drive shaft can be solid circular or hollow circular. 'ere hollow circular
cross§ion was chosen becauseC The hollow circular shafts are stronger in per kg weight than solid (ircular. The stress distribution in case of solid shaft is +ero at the center and ma8imum at the outer surface while in hollow shaft stress variation is smaller. $n solid shafts the material close to the center are not fully utili+ed.
4.6 S'&'$,#( M,'-#&+ Based on the advantages discussed earlier, the E&lassDEpo8y, 'igh 3trength (arbonDEpo8y and 'igh :odulus (arbonDEpo8y materials are selected for composite drive dri ve sha shaft. ft. Th Thee Tab able le sho shows ws the pro propert perties ies of the E& E&las lassDE sDEpo8 po8y y, 'ig 'igh h 3tr 3treng ength th (arbonDEpo8y and 'igh :odulus (arbonDEpo8y materials used for composite drive shafts.
4.7 F$,- S',% The designer must take into account the factor of safety when designing a structure. 3ince, composites are highly orthotropic and their fractures were not fully studied the factor of safety was taken as *.
4.8 T-(+#++#( T-?*'
#ction and reaction my friend. $f a person does not turn the pedal then he will stand on it and so the ma8imum tor=ue will S !body mass of the rider 8 g" 8 the length of the pedal lever. /emember to consider the gearing of the bike though. The average, fit, adult rider can produce only 4 watts or )D)hp when cycling at a continuous )*mph !)9.1kph".F !)9.1kph".F This usually happens with a pedaling speed of 5& rpm though many rider pedal faster. ;hen $ cycle, $ usually s pin at between )&)* rpm, but $ have been riding for years years and have found that the higher speed works works better for me.
Typically Typically a shaft has a circular cross section. 'owever, the shaft with other cross& sections find special application. in the design concept of a drive shaft subjected shaft subjected to a fi8ed load. # drive shaft is supported by gears !bearings" at both the ends !and at regular interval in the centre for longer shafts". The The foot pedal arrangement arrangement usually placed over the shaft in between the gears $f a device is rotating at a steady rate or is stationary, the tor=ues applied to it must add
bicycle crankset, the tor=ue applied at the pedals is e=ual and opposite that taken off by the chain, neglecting the small amount lost in friction. 2et?s look at a bicycle drivetrain starting with the cyclist?s feet. Tor=ue is conveyed from a pedal through the crank && and from the left crank, then also through the bottom& bracket spindle && to the chainwheel. enerally, enerally, the cyclist?s rising leg applies a light tor=ue opposite that of the descending leg. The chain, at the chainwheel, produces a tor=ue e=ual and opposite the sum of the tor=ues applied at the pedals. 2et?s put some numbers to this ;e assume assume that the left lef t leg is descending in mid&stroke, applying a force of ) pounds directly downward on the left pedal, while the rising right leg is applying a reverse force of ) pounds to the right pedal. (rank length is usually given in millimeters, but we?re using English measurement here, as it?s more familiar to most English& speaking readers. ;e?ll ;e?ll assume .5 foot !)4 mm" cranks. The tor=ue on the bottom&bracket spindle is 5 pound&feetC the )£ force at the pedal, times the .5 foot length of the crank. The tor=ue at the chainwheel is slightly less, .% pound feet, after we subtract the &.5 pound&foot tor=ue from the right pedal.
$n these calculations, we neglect forces which would not contribute to tor=ueC pedal force not in the direction of rotation, and the weight on the rear wheel. ;e also neglect friction, which reduces the drive force by a few percent. umbers are rounded && close, but not e8act. The ratio of the force at the pedals to drive force at the road is the gain ratio, which ratio, which can be calculated more simply as the ratio of road speed to pedal speed, like thisC )5 teethD) teeth S ).55
imits to tor!ue and dri"e force
ow, let?s look at the limits to tor=ue and to drive force.
The limit to drive force is set by front&wheel lifting, which occurs when the drive force is about )D* the weight of the cyclist and bicycle.
2et?s assume that the weight is * pounds. Then the drive force cannot e8ceed ) pounds, or the front wheel will lift.
2et?s also assume that the cyclist can push down on a pedal with a force of * pounds && somewhat more than the the cyclist?s own weight, by standing on on a pedal and pulling up on the handlebar.
Then at gain ratios below *, the cyclist?s pedaling force is capable of generating over ) pounds of drive force, and lifting the front wheel. The cyclist must avoid pedaling as hard as possible.
$n our e8ample with the .5 foot crank length and ).)) foot wheel radius, this transition occurs almost e8actly where the number of chainwheel teeth and of rear sprocket teeth is e=ual. 3o, for e8ample, if the chainwheel has * teeth and the sprocket, 1 teeth, a hard pedal stroke can lift the front wheel.
Above the transition point, torque at the chainwheel reains the sae but torque an! !rive "orce at the rear wheel !ecrease, so the cyclist can pe!al with "ull "orce, i" !esire!.
4.9 S,-'++=S,-#( R'&,#(+# The drive shaft shaft with two gears e8perience e8perience two kinds kinds of stresses, bending bending stress and shear stress. The ma8imum bending stress generated at the outer most fiber of the shaft. #nd on the other hand, the shear stress is generated at the inner most fiber. #lso, the value of ma8imum bending stress is much more than the shear stress. 3o, the design of the shaft will be based on the ma8imum bending stress and will be driven by the following formulaC :a8imum bending stress T: @ M -/ B I ;here, M is ma8imum bending moment on the shaft. - is the radius of the shaft. I is area moment of inertia of the shaft.
4.1 T-+#(& T-+#(& !*$>&#(; C$#,% T$ T$-/ -/ 3ince long thin hollow shafts are vulnerable to torsional buckling, the possibility of the torsional buckling of the composite shaft was checked by the e8pression for the torsional buckling load T cr of of a thin walled orthotropic tube, which was e8pressed below. Tcr = = !*
r * *t" !.*4*" !E 8E y1".* !t D r" ).
This e=uation has been generated from the e=uation of isotropic cylindrical shell and has been used for the design of drive shafts. 7rom the e=uation, the torsional buckling capability of composite shaft is strongly dependent on the thickness of composite shaft and the average modulus in the hoop direction.
4.11 L,'-& - !'()#(; V#:-,#( The The shaf shaftt is cons consid idere ered d as simply simply supp suppor orte ted d beam beam unde underg rgoi oing ng tran transv svers ersee vibration or can be ideali+ed as a pinned&pinned beam. atural fre=uency can be found using the following two theories.
!'-(*&&#=E*&'- !' T'-%=N $-:' $t neglects the both transverse shear deformation as well as rotary inertia effects. atural fre=uency based on the Bernoulli&Euler Bernoulli&Euler beam theory is given by, by,
T#+'(> !' T'-%=N$-, $t considers both transverse shear deformation as well as rotary inertia effects. atural fre=uency based on the Timoshenko Timoshenko beam beam theory is given by, by,
T' -'&,#( :',<''( T#+'(> () !'-(*&&#=E*&'- !' T'-#'+ The relation between Timoshenko and Bernoulli&Euler beam theories is given b y, f nt = nt = N s sf nbe nbe
D'+#;( O,##,#( 0ptimi+ation of an engineering design is an improvement of a proposed design that results in the best properties for minimum cost. :ost of the methods used for design optimi+ation assume that the design variables are continuous. $n structural optimi+ation, almost all design variables are discrete. # simple enetic #lgorithm #lgorithm !#" is used to
obtain the optimal number of layers, la yers, thickness of ply and fiber orientation of each layer. #ll the design variables are discrete in nature and easily handled by #. ;ith reference to the middle plane, symmetrical fiber orientations are adopted .
"< GA )#'-+ - ,' T-)#,#(& O,##,#( T'$(#?*'+. #s differs from traditional optimi+ation algorithm in many ways. # few are listed here. ). # does not re=uire re=uire a problem problem specific specific knowledge knowledge to carry carry out a search. search. # uses uses only the values of the objective function. 7or instance, calculus based search algorithms use derivative information to carry out a search. *. # uses a populatio population n of points points at a time in contrast contrast to the single single point point approach approach by the traditional optimi+ation methods. That means at the same time #s process a number of designs. 1. $n #, the design design variable variabless are represe represente nted d as string stringss of binary binary variabl variables es that correspond to the chromosomes in natural genetics. Thus the search method is naturally applicable for solving discrete and integer programming problems. 7or contin continuou uouss variab variable, le, the string length can be varied varied to achiev achievee any desired desired resolution. %. #s uses uses randomi+ed randomi+ed operato operators rs in place place of the usual usual determin deterministic istic ones. ones. $n every every generat generation ion,, a new set of strings strings is produc produced ed by using using random randomi+ed i+ed parents parents selection and crossover from the old generation !old set of strings".
O:'$,#' F*($,#( The The objec objecti tive ve for for the the optim optimum um desi design gn of the the comp compos osite ite driv drivee shaft shaft is the the minimi+ation of weight, so the objective function of the problem is given as
D'+#;( C(+,-#(,+ C(+,-#(,+ ). Tor=ue Tor=ue transmission capacity capacit y of the shaft T ≥ Tma8 ≥ Tma8 *. Bucking tor=ue capacity of the shaft Tcr ≥
1. 2ateral fundamental natural fre=uency ≥ crt The constraint e=uations may be written as
. /E3U2T3 5. T/0UB2E3'00T$ ;hen abnormal vibrations or noises are detected in the driveshaft area, this chart can be used to help diagnose possible causes. /emember that other components such as wheels, tires, rear a8le and suspension can also produce similar conditions. @roblem #s bicycle is accelerated from stop when gears are not shifting 6ibration at speed oise at low speed ears pitch circle is not coincide ear backlash
(aused by tor=ue is re=uired rusting
;hat to do #pply more tor=ue at starting (lean with fluids
'igh speed
:aintain low speed Universal joint #pply grease 6ibrations 6ibrations #djust the position of gears oise,0verloading,0verh 7ollow design eating characteristics
D#'-'(, T%'+ T%'+ S,+ T-(+#++#( +, These shafts transmit power between the source and the . T-(+#++#( machines machines absorbing absorbing power. The counter shafts, line shafts, shafts, overhead overhead shafts shafts and all factory shafts are transmission transmission shafts. shafts. 3ince these shafts carry machine machine parts such as pulleys, gears etc., therefore they are subjected to bending moments in addition to twisting.
e8am e8ampl ple, e, the the cran cranks ksha haft ft is an inte integr gral al part part of $.(. $.(.en engi gine ness slid slider er&c &cra rank nk mechanism. 4. A&' # shaft is called Ian a8leJ, if it is a stationary machine element and is used for the transmission of bending moment only. $t simply acts as a support for rotating bodies. A&#$,#( To support hoisting drum, a car wheel or a rope sheave. . S#()&' # shaft is called called Ia spindleJ spindleJ,, if it is a short short shaft that that imparts imparts motion motion either to a cutting tool or to a work&piece. A&#$,#(+ ). >rill press spindles&impart motion to cutting tool !i.e." drill. *. 2athe spindles&impart motion to work&piece. #part from, an a8le and a spindle, shafts are used at so many places and almost everywhere wherever power transmission is re=uired. 7ew of them areC *. A*,:#&' D-#' S, Transmits power from main gearbo8 to differential gear bo8. *. S# P-'&&'- S, Transmits power from gearbo8 to propeller attached on it. 1. "'&#$,'- T#& R,- S, Transmits power to rail rotor fan.
P-, D-#' S,
7igure.).1
2.4 D''-#,+ C('(,#(& D-#' S, ). They have less specific modulus and strength. *. $ncreased weight. 1. (onventional steel drive shafts are usually manufactured in two pieces to increase the fundamental bending natural fre=uency because the bending natural fre=uency of a shaft is inversely proportional to the s=uare of beam length and proportional to the s=uare root of specific modulus. Therefore the steel drive shaft is made in two sections connected by
more. %. $ts corrosion resistance is less as compared with composite materials. . 3teel drive shafts have less damping capacity.
2.5 M'-#,+ C+#,' D-#' S, ). They have high specific modulus modulus and strength. )). )). /educed /educed weight weight.. )*. The fundamental natural fre=uency fre=uency of the carbon fiber fiber composite drive shaft can be twice as high as that of steel or alluminium because the carbon fiber composite material has more than % times the specific stiffness of steel or alluminium, which makes it possible to manufacture the drive shaft of passenger cars in one piece. # one&piece composite shaft can be manufactured so as to satisfy the vibration re=uirements. This eliminates all the assembly, connecting the two piece steel shafts and thus minimi+es the overall weight, vibrations and the total cost )1. >ue to the weight weight reduction, fuel consumption consumption will be reduced. )%. They have high damping damping capacity hence they produce less vibration and and noise. ). They have have good good corrosion corrosion resistance. )5. reater tor=ue capacity than steel or alluminium shaft. )4. 2onger fatigue life than steel or alluminium shaft. ). 2ower rotating weight transmits more of available power. power.
2.6 D-#' S, V#:-,#( 6ibration 6ibration is the most common drive shaft problem. 3mall cars and short vans and trucks !2:6" are able to use a single drive shaft with a slip s lip joint at the front end without e8periencing any undue vibration. 'owever, with vehicles of longer wheel base, the longer drive shaft re=uired would tend to sag and under certain operating conditions would tend to whirl and then setup resonant vibrations in the body of the vehicle, which will cause the body to vibrate as the shaft whirls.
6ibration can be either transverse or torsional. Transverse vibration is the result of unbalanced condition acting on the shaft. This condition is usually by dirt or foreign material on the shaft, and it can cause a rather noticeable vibration in the vehicle. Torsional vibration occurs from the power impulses of the engine or from improper univ univer ersal sal join join angl angles. es. $t caus causes es a noti notice ceab able le soun sound d dist distur urba banc ncee and and can can caus causee a mechanical shaking. $n e8cess, both types of vibration can cause damage to the universal joints and bearings. ;hirling of a rotating shaft happens when the centre of gravity of the shaft mass is eccentric and so is acted upon by a centrifugal force which tends to bend or bow the shaft so that it orbits about the shaft longitudinal a8is like a rotating skipping rope. #s the speed rises, the eccentric deflection of the shaft increases, with the result that the centrifugal force also will increase. The effect is therefore cumulative and
violently. 7rom the theory of whirling, it has been found that the critical whirling speed of the shaft is inversely inversely proportional proportional to the s=uare s=uare of the shaft length. length. $f, therefore, therefore, a shaft having, for e8ample, a critical whirling speed of 5 revDmin is doubled in length, the critical whirling of the new shaft will be reduced to a =uarter of this, i.e. the shaft will now begin to rotate at ) revDmin. The vibration problem could solve by increasing the diameter of the shaft, but this would increase its strength beyond its tor=ue carrying re=uirements and at the same time increase its inertia, which would oppose the vehicle
3. DRIVE MEC"ANISM 3.1 I(,-)*$,#( 7or the gear&like device used to drive a roller chain, see 3procket 3procket.. This article is about mecha mechani nical cal gears gears.. 7or 7or othe otherr uses, uses, see see ear !disam !disambigua biguation" tion"Tw Two o mes meshin hing g gea gears rs transmitting rotational motion. ote that the smaller gear is rotating faster. #lthough the larger larg er gear is rotatin rotating g less =uickly, =uickly, its tor=u tor=uee is prop proportio ortionally nally greater. greater. 0ne subtl subtlety ety of this particular arrangement is that the linear speed at the pitch diameter is the same on both gears.
# ;'- or $;<''& is a rotating machine part having cut teeth teeth,, or cogs cogs,, which mesh mesh with with another toothed part in order to transmit tor=ue tor=ue,, in most cases with teeth on the one gear being of identical shape, s hape, and often also with that shape on the other gear. Two or more gears working in tandem are called a transmission transmission and and can produ produce ce a mechanical mechanical advantage advantage thr throug ough h a gear gear ratio ratio an and d th thus us ma may y be co cons nsid ider ered ed a simple machine. machine. eared devices can change the speed, tor=ue, and direction of a power a power source. source . The most common situation is for a gear to mesh with another gearA however, a gear can also mesh with a non&rotating toothed part, called a rack, thereby producing translation instead translation instead of rotation.
The gears in a transmission are analogous to the wheels in a crossed belt pulley system. #n advantage of gears is that the teeth of a gear prevent slippage. ;hen two gears mesh, and one gear is bigger than the other !even though the si+e of the teeth must match", a mechanical advantage is produced, with the rotational speeds and speeds and the tor=ues of the two gears differing in an inverse relationship.
$n transmissions which offer multiple gear ratios, such as bicycles, motorcycles, and cars, the term ;'-, as in first in first gear , refers to a gear ratio rather than an actual physical gear ge ar.. Th Thee te term rm is us used ed to de desc scri ribe be si simi mila larr de devi vice cess ev even en wh when en th thee ge gear ar ra rati tio o is continuous rather continuous rather than discrete, discrete, or when the device does not actually contain any gears, as in a continuously variable transmission. transmission. The earliest known reference to gears was circ rcaa #.>. by 'ero 'ero of #le8a le8and ndri riaa, but they can be tra racced back to the reek mechanics mechanics of the #le8andrian school in school in the 1rd century B.(. and were greatly devel elo oped by the reek polymath #rchimedes !* !*4K* 4K*)* )* B.( B.(.". .". Th Thee #ntikythera mechanism is an e8a e8ampl mplee of a ver very y ear early ly and intricate intricate gea geared red dev device, ice, designed designed to calculate astronomical positions. astronomical positions. $ts time of construction is now estimated between ) and ) B(. The definite velocity ratio which results from having teeth gives gears an advantage over other drives !such as traction drives traction drives and 6&belts" 6&belts" in precis precision ion machines machines such as watches that th at de depe pend nd up upon on an e8 e8act act ve velo locit city y rat ratio io.. $n ca cases ses wh wher eree dr driv iver er an and d fo foll llow ower er ar aree pro8imal, gears also have an advantage over other drives in the reduced number of parts re=uir re= uiredA edA the dow downsi nside de is tha thatt gea gears rs are mo more re e8p e8pens ensive ive to man manufa ufactu cture re and their lubrication re=uirements may impose a higher operating cost.
3.2 Types 3.2.1 External gear #n e8ternal gear is one with the teeth formed on the outer surface of a cylinder or cone. (onversely, 3.2.2 I(,'-(& ;'-
an internal internal gear is one with the teeth formed on the inner surface of a cylin c ylinder der or cone. 7or bevel 7or bevel gears, gears, an internal gear is one with the pitch the pitch angle e8ceeding 9 degrees. $nternal gears do not cause output shaft direction reversal.
3.2.3 L#+, ;'-+ S*- ;'-
3pur gears or straight&cut gears are the simplest type of gear. They consist of a cylinder or disk with the teeth projecting radials, and although they are not straight&sided in form !they are usually of special form to achieve constant drive ratio, mainly involute", involute", the edge of each tooth is straight and aligned parallel to the a8is of rotation. These gears can be meshed together correctly only if they are fitted to parallel parallel shafts. "'&#$& ;'-+
'elical or Fdry fi8edF gears offer a refinement over spur gears. The leading edges of the teeth are not parallel to the a8is of rotation, but are set at an angle. 3ince the gear is curved, this angling causes the tooth shape to be a segment of a heli8. heli8. 'elical gears can be meshed unparallel or crossed orientations. The former refers to when the shafts are parallel to each otherA this is the most common orientation. $n the latter, the shafts are non¶llel, and in this configuration the gears are sometimes known as Fskew gearsF. The angled teeth engage more gradually than do spur gear teeth, causing them to run more smoothly and =uietly. ;ith parallel helical gears, each pair of teeth first make contact at a single point at one side of the gear wheelA a moving curve of contact then grows gradually across the tooth face to a ma8imum then recedes until the teeth break contact at a single point on the opposite side. $n skew gears, teeth suddenly meet at a line cont co ntact act acr acros osss th thei eirr en enti tire re wi widt dth h ca caus usin ing g str stres esss an and d no noise ise.. 3k 3kew ew ge gears ars ma make ke a chara ch aract cteri erist stic ic wh whin inee at hi high gh sp speed eeds. s. ;h ;here ereas as sp spur ur ge gears ars ar aree us used ed fo forr lo low w sp speed eed applications and those situations where noise control is not a problem, the use of helical gears is indicated when the application involves high speeds, large power transmission, or where noise abatement is abatement is important. The speed is considered to be high when the pitch line velocity e8ceeds * mDs. # disadvantage of helical gears is a resultant thrust along thrust along the a8is of the gear, which needs to be accommodated by appropriate thrust bearings, bearings, and a greater degree of sliding friction between friction between the meshing teeth, often addressed with additives in the lubricant.
Skew gears 7or a ?crossed? or ?skew? configuration, the gears must have the same pressure angle and normal pitchA however, the heli8 angle and handedness can be different. The relationship between the two shafts is actually defined by b y the heli8 angle!s" of the two shafts and the handedness, as definedC ;here is the heli8 angle for the gearL The crossed configuration is less mechanically sound because there is only a point contact between the gears, whereas in the parallel configuration there is a line contact. Muite commonly, helical gears are used with the heli8 angle of one having the negative of the heli8 angle of the otherA such a pair might also be referred to as having a right& handed heli8 and a left&handed heli8 of e=ual angles. The two e=ual but opposite angles add to +eroC the angle between shafts is +ero K that is, the shafts are parallel. ;here ;here the sum or the difference !as described in the e=uations above" is not +ero the shafts are crossed. 7or shafts crossed at right angles, the heli8 angles are of the same hand because they must add to 9 degrees. D*:&' '&#$& ;'-+
>ouble hel >ouble helical ical gea gears, rs, or herringbon herringbonee gears, gears, ov overc ercom omee th thee pr prob oblem lem of a8 a8ia iall th thru rust st presented by FsingleF helical gears, by having two sets of teeth that are set in a 6 shape. # double helical gear can be thought of as two mirrored helical gears joined together. This arrangement cancels out the net a8ial thrust, since each half of the gear thrusts in the opposite direction resulting in a net ne t a8ial force of +ero. This arrangement can remove the nee need d for thr thrust ust bea bearin rings. gs. 'o 'owev wever er,, dou double ble hel helical ical gea gears rs are mor moree dif diffic ficult ult to manufacture due to their more complicated shape. 7or both possible rotational directions, there e8ist two possible arrangements for the oppositely&oriented helical gears or gear faces. 0ne arrangement is stable, and the other is unstable. $n a stable orientation, the helical gear faces are oriented so that each a8ial force is directed toward the center of the gear. $n an unstable orientation, both a8ial forces are directed away from the center of the gear. $n both arrangements, the total !or net" a8ial force on each gear is +ero when the gears are aligned correctly. $f the gears become misaligned in the a8ial direction, the unstable arrangement will generate a net force that may lead to disassembly of the gear train, while the stable arrangement generates a net corrective force. $f the direction of rotation is reversed, the direction of the a8ial thrusts is also reversed, so a stable configuration becomes unstable, and vice versa. 3table double helical gears can be directly interchanged with spur gears without any need for different bearings. !''& ;'-
# bevel gear is shaped like a right circular cone with cone with most of its tip cut off. ;hen two bevel gears mesh, their imaginary i maginary vertices must occupy the same point. Their shaft a8es also intersect at this point, forming an arbitrary non&straight angle between the shafts. The angle between the shafts can be anything e8cept +ero or ) degrees. Bevel gears with e=ual numbers of teeth and shaft a8es at 9 degrees are called miter gears.
Spiral bevels 3piral bevel gears can be manufactured as leason types !circular arc with non&constant tooth too th dep depth" th",, 0er 0erlik likon on and (ur (urve8 ve8 typ types es !ci !circul rcular ar arc wit with h con constan stantt too tooth th dep depth" th",, Nlingel eln nberg(ycl clo o&@ &@aalloid !Ep !E picy cyccloids with const staant tooth depth" or Nlingelnberg@alloid. 3piral bevel gears have the same advantages and disadvantages relative to their straight&cut cousins as helical gears do to spur gears. 3traight bevel gears are generally used only at speeds below mDs !) ftDmin", or, for small gears, ) rpm. oteC The cylindrical gear tooth profile corresponds to an involute, but the bevel gear toot to oth h pr prof ofil ilee to an oc octo toid id.. #ll tr trad adit itio iona nall be beve vell ge gear ar ge gene nerat rator orss !l !like ike l lea easo son, n, Nlingelnberg, 'eidenreichO'arbeck, and ;:;:odule" manufacture bevel gears with an octoidal tooth profile. $:@0/T#TC 7or &a8is milled bevel gear sets it is important
3implified calculated bevel gears on the basis of an e=uivalent cylindrical gear in normal section with an involute tooth form show a deviant tooth form with reduced tooth strength streng th by )&* )&*- witho without ut offs offset et and %- with offset G>iss. 'Pne 'Pnecke, cke, TU >resd >resdenH. enH. 7urthermore those Finvolute bevel gear setsF causes more noise. "%#) ;'-
'ypoid gears resemble spiral bevel gears e8cept the shaft a8es do not intersect. The pitch surfaces appear conical but, to compensate for the offset shaft, are in fact hyperboloids o hyperboloids off rev revolu olutio tion. n. 'y 'ypoi poid d gea gears rs are alm almost ost alw alway ayss des design igned ed to ope operat ratee with shafts at 9 degrees. >epending on which side the shaft is offset to, relative to the angling of the teeth, contact between hypoid gear teeth may be even smoother and more gradual than with spiral bevel gear teeth, but also have a sliding action along the meshing teeth as it rotates and therefore usually re=uire some of the most viscous types of gear oil to avoid it being e8truded from the mating tooth faces, the oil is normally designated '@ !for hypoid" followed by a number denoting the viscosity. #lso, the pinion the pinion can can be designed with fewer teeth than a spiral bevel pinion, with the result that gear ratios of 5C) and higher are feasib feasible le using a singl singlee set of hypoid gears gears . This style of gear is most commonly found driving mechanical differentialsA which are normally straight cut bevel gearsA in motor vehicle a8les.
3.3 Backlash Backlash is the error in motion that occurs when gears change direction. $t e8ists Backlash because there ther e is always some gap between the trailing trai ling face of the driving tooth and the leading face of the tooth behind it on the driven gear, and that gap must be closed before force can be transferred in the new direction. The term FbacklashF can also be used to refer to the si+e of the gap, not just the phenomenon it causesA thus, one could speak of a pair of gears as having, for e8ample, F.) mm of backlash.F # pair of gears could be designed to have +ero backlash, but this would presuppose perfection in manufacturing, uniform uniform thermal thermal e8pansion e8pansion characteristic characteristicss throughou throughoutt the system, system, and no lubricant. lubricant. Therefore, gear pairs are designed to have some backlash. $t is usually provided by reducing the tooth thickness of each gear by half the desired gap distance. $n the case of a large gear and a small pinion, however, the backlash is usually taken entirely off the gear and the pinion is given full si+ed teeth. Backlash can also be provided by moving the gears further apart. The backlash of a gear train e=uals the sum of the backlash of each pair of gears, so in long trains backlash can become a problem.
7or situations in which precision is important, such as instrumentation and control, backlash can be minimi+ed through one of several techni=ues. 7or instance, the gear can ca n be split along a plane perpendicular to the a8is, one half fi8ed to the shaft in the usual manner, the other half placed alongside it, free to rotate about the shaft, but with springs
effect, a single gear with e8panding teeth. #nother method involves tapering the teeth in the a8ial direction and providing providing for the gear to be slid in the a8ial direction direction to take up slack.
3.4 Shifting of gears $n some machines !automobiles" it is necessary to alter the gear ratio to suit the task, a process known as gear shifting or changing gear. There are several outcomes of gear shifting in motor vehicles. $n the case of vehicle noise emissions, emissions, there are higher sound levels emitted levels emitted when the vehicle is engaged engaged in lower gears. The design life of the lower ratio gears is shorter, so cheaper gears may be used !i.e. spur for )st and reverse" which tends to generate more noise due to smaller overlap ratio and a lower mesh stiffness etc. than the helical gears used for the high ratios. This fact has been utili+ed in analy+ing vehicle vehicle generated generated sound since the late late )95s, )95s, and has been been incorp incorporat orated ed into into the simulation simulation of urban roadway noise and corresponding corresponding design of urban noise barriers along roadways.
3.5 Tooth Tooth prole p role # profile is one side of a tooth in a cross section between the outside circle and the root circle. Usually a profile is the curve of intersection of a tooth surface and a plane or surface normal to the pitch surface, such as the transverse, normal, or a8ial plane. The fillet curve !root fillet" is the concave portion of the tooth profile where it joins the bottom of the tooth space. The velocity ratio is dependent on the profile of the teeth. 7riction and 7riction and wear between two gears is also dependent on the tooth profile. There are a great many tooth profiles that will give a constant velocity ratio, and in many cases, given an arbitrary tooth shape, it is possible to develop a tooth profile for the mating gear that will give a constant velocity ratio. 'owever, two constant velocity tooth profiles have been by far the most commonly commonly used in modern times. They are the cycloid and the involute involute.. The cycloid was more common until the late )sA since then the involute has largely superseded it, particularly in drive train applications. The cycloid is in some ways the more interesting and fle8ible shapeA however the involute has two advantagesC it is easier to manufacture, and it permits the center to center spacing of the gears to vary over some range without ruining the constancy of the velocity ratio. (ycloidal gears only work properly if the center spacing is e8actly right.
3.6 Gear materials umerous nonferrous alloys, cast irons, powder&metallurgy and plastics are used in the manufacture of gears. 'owever, steels are most commonly used because of their high strength&to&weight ratio and low cost. @lastic is commonly used where cost or weight is a concern. # properly designed plastic gear can replace steel in many cases because it has many desirable properties, including dirt tolerance, low speed meshing, the ability to FskipF FskipF =uite =uite well and the ability ability to be made with material materialss not needin needing g additi additiona onall lubrication. :anufacturers have employed plastic gears to reduce costs in consumer items including copy machines, optical storage devices, cheap dynamos, consumer audio e=uipment, servo motors, and printers.
3.7 The module system #s a result, the term module is usually understood to mean the pitch diameter in millimeters divided by the number of teeth. ;hen the module is based upon inch measurement measurements, s, it is known as the English module module to avoid confusion confusion with the metric module. :odule is a direct dimension, whereas diametral pitch is an inverse dimension !like Fthreads per inchF".
4. DESIGN OF CAST IRON DRIVE S"AFT 4.1 I(,-)*$,#( +,=)-#'( '( :#$%$&' is a bicycle # +,=)-# a bicycle that that uses a drive shaft instead shaft instead of a chain chain to to transm transmit it power from the pedals to the wheel through contact of gears and a shaft rod to smoothly and efficient efficient.. 3h 3haft aft dr driv ives es we were re in intr trod oduc uced ed ov over er a ce cent ntury ury ag ago, o, bu butt we were re mo most stly ly supplanted by chain&driven bicycles due to the gear ranges possible with sprockets and derailleurs. /ecently, derailleurs. /ecently, due to advancements in internal gear technology, a small number of modern shaft&driven bicycles have been introduced.
4.1.1 P*-+' ,' D-#' S, The tor=ue that is produced from the engine and transmission must be transferred to the rear wheels to push the vehicle forward moment. The drive shaft must provide a smooth, uninterrupted flow of power to the a8les. The drive shaft and differential are used to transfer this tor=ue.
4. $t must must transmit transmit tor=ue tor=ue from from the transmis transmission sion to the the pedal pedal . >uring >uring the operatio operation, n, it is necessary necessary to to transmit transmit ma8imum ma8imum low&gear low&gear tor=ue tor=ue 9. The drive drive shafts shafts must also be capable capable of rotating rotating at the the very fast fast speeds speeds re=uired re=uired by the vehicle. ). The drive shaft must also operate through constantly changing gear velocity ratio . )). The length of the drive shaft must also be be capable of changing while transmitting tor=ue. 2ength changes are caused by a8le movement due to tor=ue reaction, road deflections, braking loads and so on. # slip joint is used to compensate for this motion. )*. The slip joint is usually made made of an internal internal and e8ternal spline. spline. $t is located on the front end of the drive shaft and is connected to the transmission.
4.2 C(+,-*$,#( () <->#(; -#($#&' The term >rive shaft is used to refer to a shaft, shaft, which is used for the transfer transfer of motion from one point to another. ;hereas the shafts, which propel !push the object ahead" are referred to as the propeller shafts. 'owever the drive shaft of the automobile is also referred to as the propeller shaft because apart from transmitting the rotary motion from the front end to the rear end of the vehicle, these shafts also propel the vehicle forward. The shaft is the primary connection between the front and the rear end !engine and differential", which performs both the jobs of transmitting the motion and propelling the front end. Thus the terms >rive 3haft and @ropeller 3hafts are used interchangeably. $n other words, a drive shaft is a longitudinal power transmitting, used in vehicle where the pedal is situated at the human feet. # drive shaft s haft is an assembly ass embly of one or more tubular shafts connected by universal, constant velocity or fle8ible joints. The number of tubular pieces and joints depends on the distance between between the two wheels. The job involved is the design for suitable propeller shaft and replacement of chain drive smoothly to transmit power from the engine to the wheel without slip. $t needs only a less maintenance. $t is cost effective. @ropeller shaft strength is more and also propeller shaft diameter is less. it absorbs the shock. Because the propeller shaft center is fitted with the universal joint is a fle8ible joint. $t turns into any angular position. The both end of the shaft are fitted with the bevel pinion, the bevel pinion engaged with the crown and power is transmitted to the rear wheel through the propeller shaft and gear bo8. . ;ith our shaft drive bikes, there is no more grease on your hands or your clothesA and no more chain and derailleur maintenance. 3haft&driv 3haft&d riven en bik bikes es hav havee a lar large ge bevel bevel gear gear whe where re a con conven ventio tional nal bik bikee wo would uld hav havee its chain ring. ring. This meshes with another bevel gear gear mounted mounted on the drive shaft. The use of bevel gears allows the a8is of the drive tor=ue from the pedals to be turned through 9 degrees. The drive shaft then has another bevel gear near the rear wheel hub which meshes with a bevel gear on the hub where the rear sprocket would be on a conventional bike, and canceling out the first drive tor=ue tor=ue change of a8is.
The 9°ree change of the drive plane that occurs at the bottom the bottom bracket bracket and and again at the re rear ar hu hub b us uses es be beve vell ge gear arss fo forr th thee mo most st ef effi ficie cient nt pe perf rform orman ance, ce, th thou ough gh ot othe her r mechanisms could be used, e.g. 'obson
7ig %.).Bevel ear :echanism
4.3 S'$##$,#( )-#' +, The specifications of the composite drive shaft of an automotive transmission are same as that of the steel drive shaft for optimal design. The fundamental natural bending fre=uency for passenger cars, small trucks, and vans of the propeller shaft should be higher than 5, rpm to avoid whirling vibration and the tor=ue transmission capability of the drive shaft should be larger than 1, m. The drive shaft outer diameter should not e8ceed ) mm due to space limitations. 'ere outer diameter of the shaft is taken as 9 mm. The drive shaft of transmission system is to be designed optimally for following specified specifi ed design re=uirements as shown in Table. Table.
T:&' D'+#;( -'?*#-''(,+ () +'$##$,#(+ S.N
N'
N,,#(
U(#,
V&*'
).
Ultimate Tor=ue
Tma8
m m
1
*.
:a8.3peed of shaft
ma8
rp rpm
5
1.
2ength of 3haft
2
mm
)*
3teel !3:%(" used for automotive drive shaft applications. The material properties of the steel !3:%(" are given in Table. The steel drive shaft should satisfy three design specifications such as tor=ue transmission capability, buckling tor=ue capability and bending natural fre=uency. fre=uency. T:&' M'$(#$& -'-,#'+ C+, #-( SM45C/
S.N
M'$.P-'-,#'+
S%:&
U(#,+
C+, I-(
1.
Qoungs :odulus
E
@a
).
2.
3hear :odulus
@a
15.4
3.
@oisson /atio
v
======
.*1
4.
>ensity
R
NgDm1
4*9
5.
Qield 3trength
3y
:@a
)1
6.
3hear 3trength
3s
:@a
)59
4.4 D'+#;( A++*,#(+ ). The shaft rotates at a constant speed about its longitudinal a8is. *. The shaft has a uniform, circular cross section. 1. The shaft is perfectly balanced, i.e., at every cross section, the mass center coincides with the eometric center. %. #ll damping and nonlinear effects are e8cluded. . The The stress& stress&stra strain in relatio relationsh nship ip for compos composite ite materia materiall is linear linear O elastic elasticAA hence, hence, 'ooke
4.5 S'&'$,#( C-++=S'$,#( The drive shaft can be solid circular or hollow circular. 'ere hollow circular cross§ion was chosen becauseC The hollow circular shafts are stronger in per kg weight than solid (ircular. The stress distribution in case of solid shaft is +ero at the center and ma8imum at the outer surface while in hollow shaft stress variation is smaller. $n solid shafts the material close to the center are not fully utili+ed.
4.6 S'&'$,#( M,'-#&+
Based on the advantages discussed earlier, the E&lassDEpo8y, 'igh 3trength (arbonDEpo8y and 'igh :odulus (arbonDEpo8y materials are selected for composite drive dri ve sha shaft. ft. Th Thee Tab able le sho shows ws the pro propert perties ies of the E& E&las lassDE sDEpo8 po8y y, 'ig 'igh h 3tr 3treng ength th (arbonDEpo8y and 'igh :odulus (arbonDEpo8y materials used for composite drive shafts.
4.7 F$,- S',% The designer must take into account the factor of safety when designing a structure. 3ince, composites are highly orthotropic and their fractures were not fully studied the factor of safety was taken as *.
4.8 T-(+#++#( T-?*'
#ction and reaction my friend. $f a person does not turn the pedal then he will stand on it and so the ma8imum tor=ue will S !body mass of the rider 8 g" 8 the length of the pedal lever. /emember to consider the gearing of the bike though. The average, fit, adult rider can produce only 4 watts or )D)hp when cycling at a continuous )*mph !)9.1kph".F !)9.1kph".F This usually happens with a pedaling speed of 5& rpm though many rider pedal faster. ;hen $ cycle, $ usually s pin at between )&)* rpm, but $ have been riding for years years and have found that the higher speed works works better for me.
Typically Typically a shaft has a circular cross section. 'owever, the shaft with other cross& sections find special application. in the design concept of a drive shaft subjected shaft subjected to a fi8ed load. # drive shaft is supported by gears !bearings" at both the ends !and at regular interval in the centre for longer shafts". The The foot pedal arrangement arrangement usually placed over the shaft in between the gears $f a device is rotating at a steady rate or is stationary, the tor=ues applied to it must add up to +ero && any tor=ue applied at one point must be taken off at another. 3o, with a bicycle crankset, the tor=ue applied at the pedals is e=ual and opposite that taken off by the chain, neglecting the small amount lost in friction. 2et?s look at a bicycle drivetrain starting with the cyclist?s feet. Tor=ue is conveyed from a pedal through the crank && and from the left crank, then also through the bottom& bracket spindle && to the chainwheel. enerally, enerally, the cyclist?s rising leg applies a light tor=ue opposite that of the descending leg. The chain, at the chainwheel, produces a tor=ue e=ual and opposite the sum of the tor=ues applied at the pedals. 2et?s put some numbers to this ;e assume assume that the left lef t leg is descending in mid&stroke, applying a force of ) pounds directly downward on the left pedal,
while the rising right leg is applying a reverse force of ) pounds to the right pedal. (rank length is usually given in millimeters, but we?re using English measurement here, as it?s more familiar to most English& speaking readers. ;e?ll ;e?ll assume .5 foot !)4 mm" cranks. The tor=ue on the bottom&bracket spindle is 5 pound&feetC the )£ force at the pedal, times the .5 foot length of the crank. The tor=ue at the chainwheel is slightly less, .% pound feet, after we subtract the &.5 pound&foot tor=ue from the right pedal.
$n these calculations, we neglect forces which would not contribute to tor=ueC pedal force not in the direction of rotation, and the weight on the rear wheel. ;e also neglect friction, which reduces the drive force by a few percent. umbers are rounded && close, but not e8act. The ratio of the force at the pedals to drive force at the road is the gain ratio, which ratio, which can be calculated more simply as the ratio of road speed to pedal speed, like thisC )5 teethD) teeth S ).55
imits to tor!ue and dri"e force
ow, let?s look at the limits to tor=ue and to drive force.
The limit to drive force is set by front&wheel lifting, which occurs when the drive force is about )D* the weight of the cyclist and bicycle.
2et?s assume that the weight is * pounds. Then the drive force cannot e8ceed ) pounds, or the front wheel will lift.
2et?s also assume that the cyclist can push down on a pedal with a force of * pounds && somewhat more than the the cyclist?s own weight, by standing on on a pedal and pulling up on the handlebar.
Then at gain ratios below *, the cyclist?s pedaling force is capable of generating over ) pounds of drive force, and lifting the front wheel. The cyclist must avoid pedaling as hard as possible.
$n our e8ample with the .5 foot crank length and ).)) foot wheel radius, this transition occurs almost e8actly where the number of chainwheel teeth and of rear sprocket teeth is e=ual. 3o, for e8ample, if the chainwheel has * teeth and the sprocket, 1 teeth, a hard pedal stroke can lift the front wheel.
Above the transition point, torque at the chainwheel reains the sae but torque an! !rive "orce at the rear wheel !ecrease, so the cyclist can pe!al with "ull "orce, i" !esire!.
4.9 S,-'++=S,-#( R'&,#(+# The drive shaft shaft with two gears e8perience e8perience two kinds kinds of stresses, bending bending stress and shear stress. The ma8imum bending stress generated at the outer most fiber of the shaft. #nd on the other hand, the shear stress is generated at the inner most fiber. #lso, the value of ma8imum bending stress is much more than the shear stress. 3o, the design of the shaft will be based on the ma8imum bending stress and will be driven by the following formulaC :a8imum bending stress T: @ M -/ B I ;here, M is ma8imum bending moment on the shaft. - is the radius of the shaft. I is area moment of inertia of the shaft.
4.1 T-+#(& T-+#(& !*$>&#(; C$#,% T$ T$-/ -/ 3ince long thin hollow shafts are vulnerable to torsional buckling, the possibility of the torsional buckling of the composite shaft was checked by the e8pression for the torsional buckling load T cr of of a thin walled orthotropic tube, which was e8pressed below. Tcr = = !*
r * *t" !.*4*" !E 8E y1".* !t D r" ).
This e=uation has been generated from the e=uation of isotropic cylindrical shell and has been used for the design of drive shafts. 7rom the e=uation, the torsional buckling capability of composite shaft is strongly dependent on the thickness of composite shaft and the average modulus in the hoop direction.
4.11 L,'-& - !'()#(; V#:-,#( The The shaf shaftt is cons consid idere ered d as simply simply supp suppor orte ted d beam beam unde underg rgoi oing ng tran transv svers ersee vibration or can be ideali+ed as a pinned&pinned beam. atural fre=uency can be found using the following two theories.
!'-(*&&#=E*&'- !' T'-%=N $-:' $t neglects the both transverse shear deformation as well as rotary inertia effects. atural fre=uency based on the Bernoulli&Euler Bernoulli&Euler beam theory is given by, by,
T#+'(> !' T'-%=N$-, $t considers both transverse shear deformation as well as rotary inertia effects. atural fre=uency based on the Timoshenko Timoshenko beam beam theory is given by, by,
T' -'&,#( :',<''( T#+'(> () !'-(*&&#=E*&'- !' T'-#'+ The relation between Timoshenko and Bernoulli&Euler beam theories is given b y, f nt = nt = N s sf nbe nbe
D'+#;( O,##,#( 0ptimi+ation of an engineering design is an improvement of a proposed design that results in the best properties for minimum cost. :ost of the methods used for design optimi+ation assume that the design variables are continuous. $n structural optimi+ation, almost all design variables are discrete. # simple enetic #lgorithm #lgorithm !#" is used to obtain the optimal number of layers, la yers, thickness of ply and fiber orientation of each layer. #ll the design variables are discrete in nature and easily handled by #. ;ith reference to the middle plane, symmetrical fiber orientations are adopted .
"< GA )#'-+ - ,' T-)#,#(& O,##,#( T'$(#?*'+. #s differs from traditional optimi+ation algorithm in many ways. # few are
listed here. . # does not re=uire re=uire a problem problem specific specific knowledge knowledge to carry carry out a search. search. # uses uses only the values of the objective function. 7or instance, calculus based search algorithms use derivative information to carry out a search. 5. # uses a populatio population n of points points at a time in contrast contrast to the single single point point approach approach by the traditional optimi+ation methods. That means at the same time #s process a number of designs. 4. $n #, the design design variable variabless are represe represente nted d as string stringss of binary binary variabl variables es that correspond to the chromosomes in natural genetics. Thus the search method is naturally applicable for solving discrete and integer programming problems. 7or contin continuou uouss variab variable, le, the string length can be varied varied to achiev achievee any desired desired resolution. . #s uses uses randomi+ed randomi+ed operato operators rs in place place of the usual usual determin deterministic istic ones. ones. $n every every generat generation ion,, a new set of strings strings is produc produced ed by using using random randomi+ed i+ed parents parents selection and crossover from the old generation !old set of strings".
O:'$,#' F*($,#( The The objec objecti tive ve for for the the optim optimum um desi design gn of the the comp compos osite ite driv drivee shaft shaft is the the minimi+ation of weight, so the objective function of the problem is given as
D'+#;( C(+,-#(,+ C(+,-#(,+ ). Tor=ue Tor=ue transmission capacity capacit y of the shaft T ≥ Tma8 *. Bucking tor=ue capacity of the shaft Tcr ≥ ≥ Tma8 1. 2ateral fundamental natural fre=uency ≥ crt The constraint e=uations may be written as
. /E3U2T3 5. T/0UB2E3'00T$ ;hen abnormal vibrations or noises are detected in the driveshaft area, this chart can be used to help diagnose possible causes. /emember that other components such as wheels, tires, rear a8le and suspension can also produce similar conditions. @roblem #s bicycle is accelerated from stop when gears are not shifting 6ibration at speed oise at low speed ears pitch circle is not coincide ear backlash
(aused by tor=ue is re=uired rusting 'igh speed
;hat to do #pply more tor=ue at starting (lean with fluids
:aintain low speed Universal joint #pply grease 6ibrations 6ibrations #djust the position of gears oise,0verloading,0verh 7ollow design eating characteristics
ADVA ADVANTAGES NTAGES AND DISADVA DISADVANTAGES NTAGES
ADVANTAGES AND DISADVANTAGES
ADVANTAGES
$nitial cost is high
APPLICATION APPLICATION
APPLICATION
LIST OF MATE MATERIAL RIAL
LIST OF MATERIAL
S&. N.
PARTS
,%.
SPECIFICATION
i.
:icrocontroller unit
)
Electronic
ii.
/7 T,/
)
&
iii.
@ower supply !)*6 >.("
)
&
iv.
2(>
*
v.
(rystal 0scillator
)
&
vi.
@3
&
&
vii.
>( :otor
&
) o s
viii.
/esistors and capacitors
&
&
(onnecting ;ire
&
&
i8.
COST ESTIMATION
COST ESTIMATION
1. MATERIAL COST S&.
A*(,
PARTS
N.
,%.
R+./
i.
:icrocontroller unit
)
Electronic
ii.
@3
)
&
iii.
@ower supply !)*6 >.("
)
&
iv.
2(>
*
Two way switch
v.
(rystal 0scillator
)
&
vi.
/7 T,/
&
&
vii.
>( motor
&
) os
viii.
/esistors and capacitors
&
&
(onnecting ;ire
&
&
i8.
:aterial cost
S1
2. LA!OUR COST
@rogramming (ost S9
3. OVER"EAD C"ARGES
The overhead charges are arrived by I:anufacturing costJ :anufacturing (ost
S
:aterial (ost
S
1V9
S
%5
0verh verhea ead d (harg harges es S S
V 2abour cost
**- of the the manu manufa fact ctur uriing cost cost
TOTAL COST
Total cost
S
:aterial (ost V 2abour cost V 0verhead (harges
S
1V)9V
S
5%
Total cost for this project S 5%
CONCLUSION
CONCLUSION
CONCLUSION
7irstly the project were unable to be completed with the drive shaft due to
various problems around circumference of the bicycle ,later on this was reali+ed to run successfully with two bevel gears at both end of the drive shaft The presented work was aimed to reduce the wastage of human power !energy" on bicycle riding or any machine, which employs drive shaftsA in general it is achie achieve ved d by usin using g ligh lightt weig weight ht driv drivee shaft shaft with with beve bevell gears gears on both both side sidess designed on replacing chain transmission.
The presented work also deals with design optimi+ation i.e converting rotary
motion in linear motion with aid of two bevel gears. $nstead of chain drive one piece drive shaft for rear wheel drive bicycle have
been optimally designed and manufactured manufactured for easily power transmission. The drive shaft with the objective objective of minimi+ation of weight of of shaft which was
subject subjected ed to the constr constrain aints ts such such as tor=ue tor=ue transmi transmissio ssion n , torsio torsion n buckli buckling ng capacity , stress, strain , etc The tor=ue transmission capacity of the bicycle drive shaft has been calculated
by neglecting and considering the effect of centrifugal forces and it has been observed that centrifugal force will reduce the tor=ue transmission capacity of the shaft. The stress distribution and the ma8imum deformation in the drive shaft are the
functions of the stacking of material. The optimum stacking of material layers can be used as the effective tool to reduce weight and stress acting on the drive shaft. The design of drive shaft is critical as it is subjected to combined loads. The
designer has two options for designing the drive shaft whether to select solid or hollow shaft. The solid shaft gives a ma8imum value of tor=ue transmission but at same time due to increase in weight of shaft, shaft, 7or a given weight, weight, the hollow shaft is stronger because it has a bigger diameter due to less weight O less bending moment . The results obtained from this work is an useful appro8imation to help in the earlier stages of the development, saving development time and helping in the decision making process to optimi+e a design.
BIBLIOGRAPHY
!I!LIOGRAP"Y
REFERENCES
). /astogi, /astogi, . !*%". !*%". >esign >esign of composit compositee drive shafts shafts for automotiv automotivee applications. applications. 6isteon (orporation, (orporation, 3#E technical paper series. seri es. 2. 4111**4 >esign and #nalysis of a @ropeller 3haft of a Toyota Toyota Mualis by “Syed Hasan. 1. #.:.Ummuh #.:.Ummuhaani aani and >r.@ >
[email protected] 3adagopan I>esign, I>esign, 7abrication 7abrication and 3tress #nalys #nalysis is of a (omposite @ropeller 3haft, *))&*&)1. %. #nup #. #. Bijagare, Bijagare, @.. @.. :ehar and 6. 6.. :ujbaile :ujbaile I>esign 0ptimi+ati 0ptimi+ation on O #nalysis of >rive 3haftJ, 6ol. * !5", *)*, *)&*).
WE! REFERENCES
ttpCDDwww.atmel.comDd ynD re resou rc rcesDprodW docu mentsD doc* . h tt
httpCDDwww.ort odo8ism.roDdatasheetsDte8asinstrumentsDma8*1*.pdf
PHOTOGRAP HY
P"OTOGRAP"Y
