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

1. For a Double-threaded screw, Pitch of the helix = lead = ______ the pitch of the screw.
a) Four times
b) Thrice
c) Twice
d) One time

a) 13 of pitch of helix
b) 13 of pitch of screw
c) 14 of pitch of helix
d) The advancement is equal to pitch of helix.

Explanation: For a Double-threaded screw, Pitch of the helix = lead = Twice the pitch of the screw. 120 is 13 part of 360 (complete rotation). So the lead advances to 13 of pitch of helix and 23 of pitch of screw.

3. A triple-threaded screw advances ________ times of its pitch of screw for one complete rotation.
a) 6
b) 2
c) 3
d) 4

Explanation: In a Double-threaded screw, Pitch of the helix = lead = Twice the pitch of the screw, similarly in a triple-threaded screw, pitch of the helix = lead = Thrice the pitch of the screw and so on.

4. A multiple-threaded screw is designed in such a way for one complete rotation of screw advances to a distance of 5 times the pitch of the screw. If need to make the lead only up to 3 times of the pitch of screw then how many angles should we rotate the screw?
a) 214 degrees
b) 216 degrees
c) 120 degrees
d) 72 degrees

Explanation: Given that, for one complete rotation the screw advances to a distance of 5 times the pitch of screw but we need only 3 times the pitch of the screw. Total rotation is 360 degrees. 360 x 3/5 = 216 degrees.

5. A double –threaded screw has a pitch of screw 2 mm. How much the screw advances if it is made 3 revolutions?
a) 5
b) 6
c) 12
d) 10

Explanation: It is given the screw is double- threaded screw which advances to a distance of 2 times the pitch of screw for one complete turn also given pitch of 2 mm. so for one turn the screw advances to 2 x 2mm = 4 mm. The screw is made to turn 3 revolutions so the screw advances to 3 x 4 mm =12 mm.

6. A triple –threaded screw is made 4 revolutions. What is the pitch of screw if the screw advances to 6 cm?
a) 24 mm
b) 5 mm
c) 1 cm
d) 5 cm

Explanation: The screw advances to 6 cm = 60 mm if 4 revolutions are made that is it will advances 60/4 = 15 mm if one revolution is made. 15 mm is the pitch of the helix. Given the screw is triple –threaded so pitch of the screw is 15/ 3 = 5 mm.

7. A double–threaded screw is made _____ revolutions. The pitch of the screw is 6 mm and the screw advanced to 6 cm.
a) 6
b) 5
c) 7
d) 4

Explanation: Pitch of the screw is 6 mm given screw is double-threaded so for one revolution the screw advances to 6 mm x 2 = 12 mm. But the screw advanced to 6 cm = 60 mm. Number of revolutions = total screw advancement/ screw advancement for single revolution = 60 /12 = 5.

8. A multiple-threaded screw has a pitch of screw 4mm and if the screw is made to 5 revolutions the screw will advances to 40 mm. What type of screw is it?

Explanation: 5 revolutions = 40 mm, 1 revolution = 40mm/5 = 8 mm. Given pitch of the screw is 4 mm that is a pitch of the helix is equal to two times of pitch of the screw. So the screw used here is double-threaded screw.

9. For a triple threaded screw the pitch of the screw is 5 mm. The lead (pitch of helix) is______
a) 15
b) 8
c) 10
d) 30

Explanation: In a Double-threaded screw, Pitch of the helix = lead = Twice the pitch of the screw, similarly in a triple-threaded screw, pitch of the helix = lead = Thrice the pitch of the screw and so on. Lead = 3 x 5 mm = 15 mm.

10. The double-threaded screw is made to rotate one complete rotation the screw advanced to 10 mm. Lead (pitch of helix) is given as 10 mm. The pitch of the screw is ____
a) 10 mm
b) 5 mm
c) 1 mm
d) 12 mm

Explanation: In a double –threaded screw, the lead = the pitch of helix = 2 times of pitch of the screw. The pitch of screw = 10mm / 2 =5 mm. Even if the single- threaded screw is changed to double threaded screw the cross-section of thread and pitch of screw won’t change.

11. The double- threaded screw is made to rotate 2 revolutions for this the screw advances to 40 mm. What is the pitch of helix?
a) 40 mm
b) 10 mm
c) 20 mm
d) 22 mm

Explanation: 2 revolutions = 40 mm so 1 revolution = 40 mm/ 2 = 20 mm. In any type of screw, the advancement of screw for one revolution is equal to the pitch of the helix. So here also the pitch of helix is 20 mm.

12. The triple- threaded screw is made to rotate 10 revolutions for this the screw advances to 90 mm. What is the pitch of screw?
a) 4.5 mm
b) 9 mm
c) 1 mm
d) 3 mm

Explanation: 90 mm advance = 10 revolutions, 1 revolution = 9 mm advancement. Since it is triple threaded it advances to 3 times of pitch of the screw. Therefore the pitch of the screw is 9mm /3 = 3 mm.

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