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

1. Flank is a __________
a) line
b) point
c) distance
d) surface

Explanation: The surface between the crest and the root is called the flank of the thread. Depth is the distance between the crest and root, measured at right angles to the axis. It is equal to the half of the difference between the outside and core diameter denoted by D.

2. For a unified triangular external thread the distance between the crest and root (d) is ____ when pitch (p) is given.
a) d= 0.75 p
b) d= 0.5 p
c) d= 0.61 p
d) d= 0.64 p

Explanation: For a buttress thread the distance between the crest and root (d) is 0.75 times the pitch, for square thread ‘d’ is 0.5 times the pitch, for a Whitworth external thread ‘d’ is 0.64 times the pitch, for a unified triangular external thread the ‘d’ is 0.61 times the pitch.

3. For a Whitworth external thread the distance between the crest and root (d) is ____ when pitch (p) is given.
a) d= 0.75 p
b) d= 0.5 p
c) d= 0.61 p
d) d= 0.64 p

Explanation: For a buttress thread the distance between the crest and root (d) is 0.75 times the pitch, for square thread ‘d’ is 0.5 times the pitch, for a Whitworth external thread ‘d’ is 0.64 times the pitch.

4. For buttress thread, the angle between the two flanks is ____
a) 55 degrees
b) 47.5 degrees
c) 29 degrees
d) 45 degrees

Explanation: For buttress thread the angle between the two flanks is 45 degrees, for British association thread the angle between the two flanks is 47.5 degrees, for acme thread the angle between the two flanks is 29 degrees.

5. For acme thread, the angle between the two flanks is ____
a) 55 degrees
b) 47.5 degrees
c) 29 degrees
d) 45 degrees

Explanation: For Whitworth thread the angle between the two flanks is 55 degrees, for British association thread the angle between the two flanks is 47.5 degrees, for acme thread the angle between the two flanks is 29 degrees.
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6. For a square thread, the distance between the crest and root (d) is ____ when pitch (p) is given.
a) d= 0.86 p
b) d= 0.5 p
c) d= 0.61 p
d) d= 0.64 p

Explanation: For a buttress thread the distance between the crest and root (d) is 0.75 times the pitch, for square thread ‘d’ is 0.5 times the pitch, for a Whitworth external thread ‘d’ is 0.64 times the pitch.

7. For a buttress thread, the distance between the crest and root (d) is ____ when pitch (p) is given.
a) d= 0.86 p
b) d= 0.5 p
c) d= 0.64 p
d) d= 0.75 p

Explanation: For a buttress thread the distance between the crest and root (d) is 0.75 times the pitch, for square thread ‘d’ is 0.5 times the pitch, for a Whitworth external thread ‘d’ is 0.64 times the pitch.

8. For Whitworth thread, the angle between the two flanks is ____
a) 55 degrees
b) 47.5 degrees
c) 29 degrees
d) 45 degrees

Explanation: For Whitworth thread, the angle between the two flanks is 55 degrees, for British association thread the angle between the two flanks is 47.5 degrees, for acme thread the angle between the two flanks is 29 degrees.

9. For British association thread, the angle between the two flanks is ____
a) 55 degrees
b) 47.5 degrees
c) 29 degrees
d) 45 degrees

Explanation: For Whitworth thread, the angle between the two flanks is 55 degrees, for British association thread the angle between the two flanks is 47.5 degrees, for acme thread the angle between the two flanks is 29 degrees.

10. If a nut, when turned in clockwise direction screws on a bolt, the thread is a left-hand thread.
a) True
b) False

Explanation: If a nut, when turned in clockwise direction screws on a bolt, the thread is a right-hand thread; but if it screws off the bolt when turned in the same direction, the thread is said to be left hand thread.

11. Practical application of the right-hand, left-hand threads is made in a coupler-nut and turn-buckle.
a) True
b) False

Explanation: The length of a tie-bar can be adjusted by this nut. Looking from right, if the nut is turned in clockwise direction, the ends of the rods will move closer to each other. They will move further apart when the nut is turned in an anticlockwise direction.

Sanfoundry Global Education & Learning Series – Engineering Drawing.

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