Design of Shafts and Keys
Exam Duration: 45 Mins Total Questions : 20
The type of stress(es) developed in the key is/are
- (a)
shear stress
- (b)
bearing stress
- (c)
Both (a) and (b)
- (d)
None of the above
A keyway lowers
- (a)
the strength of the shaf
- (b)
the rigidity of the shaft
- (c)
Both (a) and (b)
- (d)
the ductility of the material of the shaft
Oldham coupling is used to connect two shafts
- (a)
which have lateral misalignment
- (b)
whose axes intersect at a small angle
- (c)
which are perfectly aligned
- (d)
which are not in exact alignment
A sliding bearing which can support steady loads without any relative motion between the journal and the bearing is called
- (a)
zero film bearing
- (b)
boundary lubricated bearing
- (c)
hydrostatic lubricated bearing
- (d)
hydrodynamic lubricated bearing
If Z = absolute viscosity of the lubricant in kg/m-s, N = speed of the journal in rpm and p = bearing pressure in N/mm2 then, the bearing characteristic number is
- (a)
\(\cfrac { Z }{ pN } \)
- (b)
\(\cfrac { pN }{ Z } \)
- (c)
\(\cfrac { ZN }{ p } \)
- (d)
\(\cfrac { Zp }{ N } \)
The tapered roller bearings can take
- (a)
Only radial load
- (b)
Only axial load
- (c)
Both (a) and (b)
- (d)
None of these
Ball and roller bearings in comparison to sliding bearings have
- (a)
small overall dimensions
- (b)
low starting and running friction
- (c)
more accuracy in alignment
- (d)
All of the above
The ball bearings are usually made from
- (a)
high speed steel
- (b)
medium carbon steel
- (c)
Both (a) and (b)
- (d)
chrome nickel steel
The piston pin bearings in heavy duty diesel engines are
- (a)
needle roller bearings
- (b)
tapered roller bearings
- (c)
cylindrical roller bearings
- (d)
spherical roller bearings
Lewis equation in spur gears is applied
- (a)
only to the pinion
- (b)
only to the gear
- (c)
to weaker of pinion or gear
- (d)
to stronger of pinion or gear
The form factor of a spur gear tooth depends upon
- (a)
pressure angle
- (b)
circular pitch
- (c)
number of teeth and circular pitch
- (d)
number of teeth and the system of teeth
The cross-section of a flat key is 16 x 10 mm. It is fitted on the shaft whose diameter is 50 mm. The key is transmit a torque 400 N-m and crusting stress is 250 N/mm2. The length of key is
- (a)
18 mm
- (b)
17 mm
- (c)
16 mm
- (d)
15 mm
A solid shaft and a hollow shaft are made from same material. The diameter of solid shaft is equal to internal diameter of hollow shaft. If they transmit same torque,
the relation between outer diameter, thickness and internal diameter of hollow shaft is (Do = outer diameter, D = internal diameter, t = thickness and t/Do << 1)
- (a)
\({ D }^{ 3 }={ D }_{ o }^{ 2 }\times 8t\)
- (b)
\({ D }^{ 3 }={ D }_{ o }^{ 3 }\times 8t\)
- (c)
D=Dot
- (d)
\({ D }_{ 2 }={ D }_{ 0 }^{ 2 }.t\)
In above question what is the ratio thickness to outer diameter?
- (a)
\(\cfrac { 1 }{ 16 } \)
- (b)
\(\cfrac { 1 }{ 13 } \)
- (c)
\(\cfrac { 1 }{ 18 } \)
- (d)
\(\cfrac { 1 }{ 14 } \)
If the dynamic load carrying capacity of a ball bearing increased 2 times without change in equivalent dynamic load, the life of bearing is increased
- (a)
600%
- (b)
800%
- (c)
700%
- (d)
400%
The radial load on a ball bearing is 8000 N. The expected life for bearing 6000 h (reliability 90%). If shaft is rotated at 2000 rpm then, dynamic load carrying capacity of ball bearing is
- (a)
71702.47 N
- (b)
70702.47 N
- (c)
72702.47 N
- (d)
73702.47 N
If a ball bearing is coded by 6310 then, bore diameter of bearing is
- (a)
40 mm
- (b)
30 mm
- (c)
50 mm
- (d)
60 mm
A 80 mm long journal bearing supports 2800 N load on a 50 mm diameter shaft. The diametral clearance is 0.1 mm and shaft speed is 2000 rpm. If viscosity of oil is 0.021 kg/m-s then, the value of friction coefficient is
- (a)
0.0119
- (b)
0.117
- (c)
1.1
- (d)
1.2
A ball bearing sustain a radial load 3672 N. The diameter of bearing is 60 mm and its length is 90 mm. Diametral clearance is 0.1 mm and shaft rotates at 450 rpm. If oil
viscosity is 0.06 kg/m-s, the value of Sommerfeld number is
- (a)
17 x 106
- (b)
14.3 x 106
- (c)
15.3 x 106
- (d)
16.3 x 106
A pair of spur gear with 200 full depth involute teeth having module 5 mm, face width 50 mm and beam stress is200 N/mm2. If Lewis form factor is 0.308, the value of beam strength is
- (a)
15400 N
- (b)
14000 N
- (c)
11000 N
- (d)
12000 N