ALCORCON ENGINEERING REVIEW CENTER MACHINE DESIGN – WORM, HELICAL AND BEVEL GEAR PROBLEM SET # 4
INSTRUCTION: Encircle the letter that corresponds to the correct answer of o!r choice" #ULTI$LE C%OICE: &" A wor' rotatin( rotatin( at &&)* rp+ dri,es a wor+ (ear" (ear" The ,elocit ratio is &) to &" A &* hp +otor is !sed to s!ppl s!ppl the wor+ pitch (ear dia+eter of - in" .ind the tan(ential force on the wor+" A" -/)"-0 l1s 2" 3/)"-0 l1s C" )/)"-0 l1s 4"//)"-0 l1s 5" A do!1le thread wor+ wor+ (ear has a pitch of & &67 and a pitch dia+eter dia+eter of - in" It has a coe8cient coe8cient of friction of *"5* and nor+al an(le 9press!re an(le of &3");" The wor+ is s!pplied 1 &5 hp at &5** rp+ +otor" .ind the tan(ential force on the (ear" The wor+ is left hand threads A" )<0"*7 l1s 2" /<0"*7 l1s C" 0<0"5- l1s 4" 7<0"*7 l1s -" A sin(le wor+ wor+ (ear has a pitch pitch dia+eter dia+eter of 5 in and a pitch pitch of & in with coe8cient of friction friction of *"5&" The nor+al an(le is &3") de(rees with tan(ential force on (ear of &*** l1s" .ind the separation force on (ear and wor+ considerin( a left hand threads A" &0&"5- l1s 2" 50&"5- l1s C" -0&"5- l1s 4" 30&"5- l1s 3" A do!1le thread wor+ wor+ (ear has a lead an(le of of 0"5) de(rees and pitch radi!s radi!s of 5 = in" .ind the pitch pitch of the wor+" A" > in 2" = in C" & in 4" & = in )" A triple thread wor+ wor+ (ear has a heli? an(le o off 07 de(rees" It has a pitch of @ in" .ind .ind the pitch dia+eter dia+eter of the (ear" A" 5"-0 in 2" 5"00 in C" -"*0 in 4" -"-0 in /" A do!1le thread wor+ wor+ has a lead of &") in and pitch dia+eter dia+eter of -") in" If nor+al press!re press!re an(le is &3") de(rees Bnd the press!re an(le of the wor+" A" &&"/7 2" &5"/7 C" &-"/7 4" &3"/7 0" A triple thread thread wor+ (ear (ear has pitch of @ in and pitch dia+eter dia+eter of 5 > in" in" .ind .ind the heli? an(le" an(le" A" 05"-3 2" /5"-3 C" )5"-3 4" 35"-3
7" A threeDthread wor+ (ear rotatin( at &*** rp+ dri,es a -&Dtooth (ear" .ind the Bnd the speed of the (ear" A" 0/"00 rp+ 2" 7/"00 rp+C" in" The (ear has )5 teeth of & @ in pitch" .ind the center distance of the shafts" A" &5"/& in 2" &3"/& in C" &/"/& in 4" &7"/& in &0" A wor+ has fo!r threads of &3"); nor+al press!re an(le and pitch dia+eter of 3 > in" The (ear has )5 teeth of & @ in pitch" .ind the e8cienc of the wor+ if friction is *"*-" A" 75"77 2" 7/"77 C" 7<"77 4" <5 77
&7"A triple thread wor+ has a pitch dia+eter of - inches" The wheel has 5) teeth and a pitch dia+eter of ) inches" #aterial for 1oth the wor+ and the wheel is of phosphor 1ronFe" A" *"5* 2" *"-* C" *"3* 4" &3 &<"A triple thread wor+ (ear is !se to dri,e a 5) teeth (ear ha,in( a pitch of @ in" .ind the center distance" A" 5"-3 in 2" -"-3 in C" 3"-3 in 4" )"-3 in 5*"A do!1le thread ri(ht handed wor+ (ear trans+its &) hp at &&)* rp+" The pitch of the wor+ is *"0) inches and pitch dia+eter of - inches" The press!re an(le is &3 and = de(rees and the coe8cient of friction is *"&5" .ind the separatin( force in po!nds" A" )*3 l1s 2" )*& l1s C" 3*0 l1s 4" )*<& l1s 5&"A 5*Dtooth helical (ear has a pitch dia+eter of &* in" .ind the dia+etral pitch of the (ear" A" 5 2" C" 3 4" ) 55"A 57D tooth helical (ear ha,in( a pitch dia+eter of 0 has a heli? an(le of 55 de(rees" .ind the circ!lar pitch in a plane nor+al to the teeth" A" *")57 2" *"/57 C" *"057 4" *"757 5-"A helical (ear ha,in( a heli? an(le of 5-; and press!re an(le of 5* ;" .ind the press!re an(le nor+al to the teeth" A" *"5-) 2" *"--) C" *"3-) 4" *")-) 53"A 0) hp +otor r!nnin( at 3)* rp+ is (eared to a p!+p 1 +eans of helical (ear ha,in( a pinion dia+eter of 7 in" .ind the tan(ential force of the (ear" A" 5-5/ l1s 2" 535/ l1s C" 5)5/ 4" 5/5/ 5)"A t!r1ine at -**** rp+ is !se to drice a red!ction (ear deli,erin( - hp at -*** rp+" The (ears are 5* de(rees in,ol!te herrin(1one (ears of 57 pitch and 5 &67 in eecti,e width" The pinion has 5* teeth with a heli? an(le of 5- de(" 4eter+ine the load nor+al to the tooth s!rface" A" 5*"3 l1s 2" 53"3 l1s C" 57"3 l1s 4" -5"3 l1s 5/"A helical (ear ha,in( 5* teeth and pitch dia+eter of ) in" .ind the nor+al dia+etral pitch if heli? an(le is 55 de(rees" A" -"-& in 2" 3"-& in C" )"-& in 4 " /"-& in 50"A helical (ear tan(ential load of 5** l1s and a?ial load of 0- l1s" .ind the heli? an(le A" &3 de(rees 2" &/ de(rees C" &7 de(rees 4" 5* de(rees 57"A helical (ear ha,in( 5* teeth and pitch dia+eter of ) in" .ind the nor+al dia+etral pitch if heli? an(le is 55 de(rees" A" -"-& in 2" 3"-& in C" )"-& in 4" /"-& in 5<"Two helical (ear trans+it )* hp at -/** rp+" Tha sho!ld 1e the 1ore dia+eter of each (ear 1e if the allowa1le stress in (ear shaft is &5)** psiH A" &"5)5 in 2" &"-50) in C" &"3)/7 in 4" &")50/
-*"A 5*; f!ll depth strai(ht tooth (ear has a face width of - @ in and a pitch dia+eter of &5 in with a cone pitch an(le of -"0);" .ind the +ean dia+eter A" /"05 in 2" 0"05 in C" 7"05 in 4" <"05 -&"A strai(ht tooth 1e,el (ear has a face width of 3 and a pitch dia+eter of &3 in with cone pitch an(le of 3* ;" If the torJ!e on the (ear is 7***inDl1 what is the tan(ential force on the (earH A" &3** l1s 2" &3** l1s C" &3** l1s 4" &3** l1s -5"A pair of strai(ht tooth 1e,el (ear KKKKKKK pair of shaft <*;" The ,elocit ratio is - to &" What is the cone pitch an(le of s+aller (earH A" 0&")0 de(" 2" /)"-3 C" &7"3- de( 4" 5-"-3 de( --"A spiral 1e,el pinion with a left hand spiral rotates cloc'wise trans+its power to a +atin( (ear with speed ratio of 5 to &" 4eter+ine the pitch an(le of the pinion" A" &/")/ de( 2" 5*")/ de( C" 5/")/ de( 4" -5")/ de( -3"A spiral 1e,el pinion with a left hand trans+its 3 hp at &5** rp+ to a +atin( (ear" The +ean dia+eter of the pinion is - in" .ind the tan(ential force at the +ean redi!s of the (ear" A" &&* l1s 2" &5* l1s C" &-* l1s 4" &3* l1s -)"A pair of 3Dpitch &3"); in,ol!te 1e,el (ear ha,e 5:& red!ction" The pitch dia+eter of the dri,er is &* in and face width of 5 in" 4eter+ine the face an(le of pinion" 9shafts at ri(ht an(le A" 5*"7) def 2" 5-"7) de( C" 57"7) de( 4" 50"7) de( -/"The cone an(le of pinion of a pair of 1e,el (ear is -*; while for the (ear /*;" If the pinion t!rns at -** rp+ Bnd the speed of the (ear" A" &0-"5& rp+ 2" &7-"5& rp+ C "&<-"5& rp+ 4" 5*-"5& rp+ -0"The cone an(le of pinion and the (ear are 5); and /); respecti,el" .ind the speed ratio" A" &") 2" )"5 C" 3"54" 5"&3 -7" A pair of 1e,el (ear ha,in( a speed ratio of - has a )Dpitch at &3") de( in,ol!te" The pitch an(le of the pinion is 7 in" .ind the addend!+ an(le of the pinion" 9At ri(ht an(le 1etween shafts A" *"<*/; 2" &"3); C" 5"-3; 4" -"5*; -<"A pair of 1e,el (ear ha,in( a speed ratio of 5 has 3Dpitch at &3"); in,ol!te" The pitch dia+eter of pinion is 0 in" .ind the dedend!+ an(le of the (ear" A" &"&& de( 2" 5"&& de( C" -"&& de( 4" 3"&& de( 3*"A Class - pinion 1e,el (ear is +ade of allo steel hardened to -** 2rinell" The pinion r!ns at 7)* rp+ with ) in pitch dia+eter" .ind the (ear stress at factor of safe -" A" -)*5- psi 2" 3)*5- psi C" ))*5- psi 4" /)*5- psi 3&"Co+p!te the pitch an(le of a 1e,el (ear (i,en the pinions n!+1er of teeth of &3 and 35 teeth on the (ear" A" &7"3 2" 57"3 C" --"3 4" -7"3 35"In a standard 1e,el (ear the pinion rotate at &)* rp+ its n!+1er of teeth is &3 while the (ear has 35 teeth what is the pitche an(le of the pinionH
A" &7"3 de(rees 2" 5* de(rees C" &3") de(rees 4" 5*") de(rees 3-"A fo!r wheel ,ehicle +!st de,elop a drawD1ar p!ll of &0)** l1s" The en(ine which de,elops )** hp and dri,e )** hp and dri,es thro!(h a (ear trans+ission a -3 tooth spiral 1e,el pinion (ear which +eshes with a spiral 1e,el (ear ha,in( )& teeth" This (ear is 'eed to the dri,e shaft oth the 37 dia+eter rear wheel of the ,ehicle" What trans+ission (ear ratio sho!ld 1e !sed if the en(ine de,elops +a?i+!+ torJ!e at &)** rp+H Note the e8cienc of the 1e,el (ear dierential is 7*" A" &0"3<-:& 2" &/"//0:& C" &7")/5:5 4" &&"3<5:5
