MCQs on Power Screws & Self Locking Screws
1 - Question
A power screw is only used to convert rotary motion into linear motion and not for transmitting power.
a) True
b) False
View Answer
Answer: b
Explanation: Power screw converts the motion from rotary to linear and is used for power transmission.
2 - Question
Depending upon the holding arrangement, power screws operate in how many different arrangements.
a) 2
b) 3
c) 4
d) 5
View Answer
Answer: a
Explanation: There are two types of arrangements. In one screw rotates while nut remains stationary and vice versa.
3 - Question
A power screw has no problem of wear as there is very less amount of friction associated.
a) True
b) False
View Answer
Answer: b
Explanation: Wear is a serious problem in power screws as there is high friction in threads.
advertisement
4 - Question
V threads are highly recommended for fastening as well as power transmission purpose.
a) Yes
b) Never
c) In some cases
d) Can’t be stated
View Answer
Answer: b
Explanation: In fastening, high frictional force is required and hence V threads are used whereas in power transmission, reduction in frictional forces is required.
5 - Question
Trapezoidal threads are better than square threads as there is radial pressure or side thrust on the nut.
a) True
b) False
View Answer
Answer: b
Explanation: Trapezoidal and not square threads suffer from the problem of bursting.
6 - Question
Trapezoidal threads screws have less load carrying capacity as compared to square thread screws.
a) True
b) False
View Answer
Answer: b
Explanation: Square threads have less thickness at the core diameter and hence lower load carrying capacity.
7 - Question
Which of the following are true for buttress threads?
a) Combination of square and trapezoidal threads
b) Transmit motion in one direction only
c) They are used in vices
d) All of the mentioned
View Answer
Answer: d
Explanation: As force is applied only in one direction in a vice so buttress threads are used.
8 - Question
Tr 40 x 14(P 7), here 14 indicates
a) Pitch
b) Lead
c) Diameter
d) None of the mentioned
View Answer
Answer: b
Explanation: Tr=Trapezoidal threads,14=Lead(mm),7=Pitch(mm).
9 - Question
Nominal diameter of the screw thread is the same as core diameter.
a) True
b) False
View Answer
Answer: b
Explanation: Nominal diameter is the largest diameter while core diameter is the smallest diameter of the screw thread.
10 - Question
If nominal diameter of screw thread=50mm and pitch=10mm then the mean diameter of the screw thread will be?
a) 40mm
b) 45mm
c) 60mm
d) 55mm
View Answer
Answer: b
Explanation: Diameter(mean)=Diameter(nominal) – 0.5P .
11 - Question
If the load itself begin to the screw and descend down, unless a restraining torque is applied then the condition is termed as
a) Halting
b) Overhaulting
c) Front driving
d) None of the mentioned
View Answer
Answer: b
Explanation: Overhaulting is the condition when load itsel begin to turn the screw.
12 - Question
Self-locking takes place when
a) Coefficient of friction is equal to or greater than the tangent of the helix angle
b) Coefficient of friction is lesser than or equal to the tangent of the helix angle
c) Coefficient of friction is equal to or greater than the tangent of the helix angle
d) None of the mentioned
View Answer
Answer: c
Explanation: Self locking takes place if load does not descend on its own and that is possible only in c condition.