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(1) The center distance separability of a pair of involute spur cylindrical gears implies that a change in center distance does not affect the . rUmaKh?v|X
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A. radii of the pitch circles B. transmission ratio C. working pressure angle ~x4]^XS
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(2) The main failure form of the closed gear drives with soft tooth surfaces is the . ~U}0=lRVS
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A. pitting of tooth surfaces B. breaking of gear tooth #%5[8~&
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C. wear of tooth surfaces D. agglutination of tooth surfaces ]O]6O%.ao
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(3) The tooth form factor in calculation of the bending fatigue strength of tooth root is independent of the . rrz^LD
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D. helix angle of helical gear Bre:_>*
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(4) The contact fatigue strength of tooth surfaces can be improved by way of . +@G#Z3;l!
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A. adding module with not changing the diameter of reference circle `"Lk@
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B. increasing the diameter of reference circle efN5(9*9R
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C. adding tooth number with not changing the diameter of reference circle Ndmki
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D. decreasing the diameter of reference circle H'a6]
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(5) In design of cylindrical gear drives, b1 = b2 +(5~10)mm is recommended on purpose to . (Where b1, b2 are the face widths of tooth of the smaller gear and the large gear respectively.) Jo'~oZ$
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A. equalize strengths of the two gears B. smooth the gear drive s'B$/qCkR
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C. improve the contact strength of the smaller gear ,eSII2,r4
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D. compensate possible mounting error and ensure the length of contact line SiLWy=qbR
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(6) For a pair of involute spur cylindrical gears, if z1 < z2 , b1 > b2 , then . VW\xuP
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(7) In a worm gear drive, the helix directions of the teeth of worm and worm gear are the same. NjFlV(XT}
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(8) Because of , the general worm gear drives are not suitable for large power transmission. Ju-#F@38
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C. the lower strength of worm gear D. the slower rotating velocity of worm gear ST1;i5
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(9) In a belt drive, if v1, v2 are the pitch circle velocities of the driving pulley and the driven pulley respectively, v is the belt velocity, then . :Qu.CvYF
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(10) In a belt drive, if the smaller sheave is a driver, then the maximum stress of belt is located at the position of going . ]D_
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C. out of the driving sheave D. out of the driven sheave $Yj4&Two<
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(11) In a V-belt drive, if the wedge angle of V-belt is 40°,then the groove angle of V-belt sheaves should be 40°. ~p { fl?
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(12) When the centerline of the two sheaves for a belt drive is horizontal, in order to increase the loading capacity, the preferred arrangement is with the on top. _SrkR7
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(13) In order to , the larger sprocket should normally have no more than 120 teeth. 5XZ
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B. ensure the strength of the sprocket teeth C. limit the transmission ratio Wdp4'rB
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D. reduce the possibility that the chain falls off from the sprockets due to wear out of the 2+C8w%F8
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(14) In order to reduce velocity nonuniformity of a chain drive, we should take . `cqZ;(^
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2. (6 points) Shown in the figure is the simplified fatigue limit stress diagram of an element. ,E8~^\HV
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If the maximum working stress of the element is 180MPa, the minimum working stress is -80MPa. Find the angle q between the abscissa and the line connecting the working stress point to the origin. uT{.\qHo
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3. (9 points) Shown in the figure is the translating follower velocity curve of a plate cam mechanism. IP+1 :M
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(1) Draw acceleration curve of the follower schematically. 7`6JK
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(2) Indicate the positions where the impulses exist, and determine the types of the impulses (rigid impulse or soft impulse). [8C6%n{W
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(3) For the position F, determine whether the inertia force exists on the follower and whether the impulse exists. m1lfC
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4. (8 points) Shown in the figure is a pair of external spur involute gears. #/9(^6f:
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The driving gear 1 rotates clockwise with angular velocity while the driven gear 2 rotates counterclockwise with angular velocity . , are the radii of the base circles. , are the radii of the addendum circles. , are the radii of the pitch circles. Label the theoretical line of action , the actual line of action , the working pressure angle and the pressure angles on the addendum circles , . `-N&cc
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5. (10 points) For the elastic sliding and the slipping of belt drives, state briefly: b\w88=|
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(1) the causes of producing the elastic sliding and the slipping. =7mR#3yt
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(2) influence of the elastic sliding and the slipping on belt drives. )Oz( <vxw
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(3) Can the elastic sliding and the slipping be avoided? Why? tH"SOGfSt
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6. (10 points) A transmission system is as shown in the figure. N@MeaO
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The links 1, 5 are worms. The links 2, 6 are worm gears. The links 3, 4 are helical gears. The links 7, 8 are bevel gears. The worm 1 is a driver. The rotation direction of the bevel gear 8 is as shown in the figure. The directions of the two axial forces acting on each middle axis are opposite. 2hJ{+E.m
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(1) Label the rotating direction of the worm 1. :LBe{Jbw
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(2) Label the helix directions of the teeth of the helical gears 3, 4 and the worm gears 2, 6. km c9P&
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