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This set of Engineering Drawing Multiple Choice Questions & Answers (MCQs) focuses on “Types of Screw Threads”.

a) 45°
b) 60°
c) 55°
d) 30°

Explanation: British Standard Fine (B.S.F), British Standard Whitworth (B.S.W) are the screw threads that are much used in British machinery. The screw profiles of B.S.W have a thread angle of 55°, and the round ends.

2. B.S.F screw threads belong to coarse series.
a) True
b) False

Explanation: British Standard Fine (B.S.F) are the fine thread systems, they have a fine pitch in inch units. They have a wave-like thread profile which makes them less liable to damage.

3. Find the type of screw thread the following screw profile is indicating.

Explanation: The shape of the screw profile is V and the thread angle is 60°. Hence it is called as V-threads, they have a sharp end with large contact area.
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4. Which screw thread profile is the combination of square and V- threads?
a) B.S.F

a) 45°
b) 60°
c) 55°
d) 30°

Explanation: V-thread profile has a thread angle of 60°, with sharp edges and a large area of contact. They provide more frictional resistance, hence they need to be properly placed.

6. Find the type of screw thread the following profile is illustrating.

Explanation: The screw thread profile indicates a square shape, hence it is a square thread. They are the ideal threads for power transmission. Here force between threads is normal and has no radial component.

a) 45°
b) 60°
c) 55°
d) 29°

Explanation: ACME threads are the trapezoidal thread forms. They have the thread angle of 29°. They are the modified square thread forms and are stronger than square threads.

8. Find the type of screw thread the following profile is illustrating.

Explanation: They are the type of screw threads which are suitable for worms of worm gears. They have the thread angle of 29°.

a) True
b) False

Explanation: Worm threads have a similar profile as ACME threads but the depth of worm threads is 0.69P whereas in ACME it is 0.5P. Hence worm threads are deeper than ACME threads.

10. Find the type of screw thread the following profile is illustrating.

11. Find the type of screw thread the following profile is illustrating.

Explanation: The screw profile given is a combination of V and square threads, it is buttress threads. They are also called as breech-lock thread forms. Used in a screw press, Carpenter’s vice.

12. Find the type of screw thread the following profile is illustrating.

Explanation: The given profile is in a wave-like shape with thread angle 55°, hence it is British Standard Whitworth thread which also called as Whitworth thread.

13. Threads designed to handle high axial thrust in one direction is ___

Explanation: It has a slight slant face with a 7° inclination, which bears the load, and the other face is inclined about 45°, which has low friction. Hence buttress threads transmit power in one direction.

14. A thread designation is given as SQ 20 x 5, what does that indicate?
a) A square thread of pitch 5 mm and 20 mm is the nominal diameter
b) A square thread of pitch 20 mm and 100 mm is the nominal diameter
c) A thread of pitch 5 mm and 20 mm is the nominal diameter
d) A thread of pitch 20 mm and 5 mm is the nominal diameter

Explanation: For easy reading of drawings, screw threads are designated in diameter-pitch combination. SQ indicates the shape of screw threads as square, 20 mm as nominal diameter, and 5mm as pitch.

Explanation: V-threads are also called a unified thread. They are recommended by the International organization for standards, which are adopted by B.I.S.

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