看不到什么东西啊 edfb7prfTl
9f3rMPVh(
(ZD~Q_O-
(1) The center distance separability of a pair of involute spur cylindrical gears implies that a change in center distance does not affect the . Ce@"+k+w
B[7Fq[.mh
A. radii of the pitch circles B. transmission ratio C. working pressure angle .oe\wJ S6
|I=GI]I
(2) The main failure form of the closed gear drives with soft tooth surfaces is the . FND+Ok&
I=4G+h5p
A. pitting of tooth surfaces B. breaking of gear tooth =O~Y6|
U%aDkC+M
C. wear of tooth surfaces D. agglutination of tooth surfaces hJ*#t<.<P;
Qs8Rb ]%|
(3) The tooth form factor in calculation of the bending fatigue strength of tooth root is independent of the . ,o6,(jJU
rTA#4.*&
A. tooth number B. modification coefficient C. module 8MBvp*
Lz`_&&6
D. helix angle of helical gear *XluVochrb
.|2[!7CXH
(4) The contact fatigue strength of tooth surfaces can be improved by way of . &B} ,xcNO
C9nCSbGMY{
A. adding module with not changing the diameter of reference circle ME'LZ"VT
zB#.EW
B. increasing the diameter of reference circle \_t[\&.a}
o(oD8Ni
C. adding tooth number with not changing the diameter of reference circle \-{2E
7G
3e
D. decreasing the diameter of reference circle fWl #CI\]
>$;,1N $bd
(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.) J''lOj(@
$x(p:+TI\4
A. equalize strengths of the two gears B. smooth the gear drive O\}w&BE:h
P+Sgbtc
C. improve the contact strength of the smaller gear
w,;ox2
lrK?&a9AB
D. compensate possible mounting error and ensure the length of contact line 9K=K,6
b
k3&
/Ei5
(6) For a pair of involute spur cylindrical gears, if z1 < z2 , b1 > b2 , then . t7,** $ST
FOS*X
A. B. C. D. N'I9J?e Q
`6pz9j]
(7) In a worm gear drive, the helix directions of the teeth of worm and worm gear are the same. ,gIeQ!+vy
f:ep~5] G
A. certainly B. not always C. certainly not
{5JYu
F-2Q3+7$
(8) Because of , the general worm gear drives are not suitable for large power transmission. @Qd5a(5W M
X92I==-w
A. the larger transmission ratios B. the lower efficiency and the greater friction loss /n3S E0Y
)H%RwV#
C. the lower strength of worm gear D. the slower rotating velocity of worm gear xhncQhf\
g\@zQ^O?
(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 . tCQf `
2o~UA\:+=
A. B. C. D. gX/?
$A>]lL
o0
(10) In a belt drive, if the smaller sheave is a driver, then the maximum stress of belt is located at the position of going . k(_^Lq f-
&}FWpo!
A. into the driving sheave B. into the driven sheave sUpSXG-W/@
hIwqSKq9
C. out of the driving sheave D. out of the driven sheave ^6 \@$
v8K4u)
(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°. `6o5[2V
,ydn]0SS
A. greater than B. equal to C. less than D. not less than 1"U.-
I@
]u
"x=S93
(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. /
(Ryh6M
Qz([\Xx:
A. slack side B. tight side BU=Ta$#BZ
]wV_xZ)l^A
(13) In order to , the larger sprocket should normally have no more than 120 teeth. USbFUHdDc
&5R-bYGW
A. reduce moving nonuniformity of a chain drive kl#)0yqN0
y(jd$GM|
B. ensure the strength of the sprocket teeth C. limit the transmission ratio JO\KTWtjO
kj
'
D. reduce the possibility that the chain falls off from the sprockets due to wear out of the
ie
<m)
k]yv#Pa
chain $ZnVs@:S
0Y/k/)Ul]
(14) In order to reduce velocity nonuniformity of a chain drive, we should take . ?,FL"ye
eLk:">kj
A. the less z1 and the larger p B. the more z1 and the larger p u1/q8'RW
(t"rzH
C. the less z1 and the smaller p D. the more z1 and the smaller p }xytV5a^
Fzn#>`qG
(Where z1 is the tooth number of the smaller sprocket, p is the chain pitch) 'jBtBFzP-
bE2{^5
iG
(15) In design of a chain drive, the pitch number of the chain should be . _OR[RGy
n16TQe"8
A. even number B. odd number C. prime number Ct}rj-L<i
mJS-x-@
D. integral multiple of the tooth number of the smaller sprocket l u
V_
d$v{oC}
6>-Gi
q@iZo,Yk
2. (6 points) Shown in the figure is the simplified fatigue limit stress diagram of an element. [300F=R
szD
BfGd%j
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. IR<*OnKn
_tVrLb7`s
!6{b)P
[NguQ]B.
+/2:
?iNihE
3. (9 points) Shown in the figure is the translating follower velocity curve of a plate cam mechanism. u"M^qRhD
Op:7Ed
T#
(1) Draw acceleration curve of the follower schematically. %'<m[wf^ o
R3} Z"
(2) Indicate the positions where the impulses exist, and determine the types of the impulses (rigid impulse or soft impulse). zd#/zUPI
b:(*C
(3) For the position F, determine whether the inertia force exists on the follower and whether the impulse exists. ~CL^%\K
a+{95"4
^)|1T#Tz
'Z(4Wuwb
cE0Kvqe`
sy.U]QG
>
VWH
bo
-QUvd1S40
)0NE_AZ?
SgocHpyg
$N1UEvC%Q
fr<, LC.
4. (8 points) Shown in the figure is a pair of external spur involute gears. a7UfRG
x9!vtrM\Zr
The driving gear 1 rotates clockwise with angular velocity while the driven gear 2 rotates counterclockwise with angular velocity . , are the radii of the base circles. , are the radii of the addendum circles. , are the radii of the pitch circles. Label the theoretical line of action , the actual line of action , the working pressure angle and the pressure angles on the addendum circles , . (l3P<[[?
&Kgl\;}
0jN?5j
enGjom
D>Qc/+
R_2JP C
5. (10 points) For the elastic sliding and the slipping of belt drives, state briefly: 2!35Tj"RFE
,@Izx
(1) the causes of producing the elastic sliding and the slipping. V5{^R+_)Ya
LGm>x
(2) influence of the elastic sliding and the slipping on belt drives. !~&vcz0>)9
Gq/f|43}@O
(3) Can the elastic sliding and the slipping be avoided? Why? zU9G:jH
bNG;`VZ%
B|Rnh;B-
JL4\%
H0
YxPk)
I~$LIdzw
ji[O?
;$y(Tvd;
]r{-K63P{!
oO4
Wwi
^ )Lh5
zOpl
#%"
6.Nu[-?
h7-!
q@
Ne<"o]_M
kN4nRW9z
aPq9^S*
U/2g N
H
g<