Deck 12: Mechanical Power Transmission

Question 1

In a simple machine which has a velocity ratio of 8 and the law giving the relationship between the effort E and load F is E = 0.2F + 0.25 N, the limiting efficiency is:

A) 0.2
B) 0.25
C) 0.5
D) 0.63

Answer 1

D

Question 2

In a simple machine which has a velocity ratio of 8 and the law giving the relationship between the effort E and load F is E = 0.2F + 0.25 N, the effort required to overcome friction is:

A) 0.2 kN
B) 0.25 kN
C) 1.6 kN
D) 4.0 kN

Answer 2

B

Question 3

A screw jack has a screw with a pitch of 12 mm and a jack handle with a radius of rotation of 0.4 m. If the load to be lifted by the jack is 10 kN, the effort that must be applied to the jack handle is:

A) 47.6 N
B) 95.6 N
C) 191.2 N
D) 300 N

Answer 3

A

Question 4

Decide whether each of these statements is True (T) or False
A 100% efficient gear system has a gear ratio of 3 to 1. When a torque of 200 N is applied and the input
Shaft rotates at 20 rev/s:
(i) The output shaft rotates at 30 rev/s.
(ii) The output shaft torque is 600 N m.

A) (i) F (ii) F
B) (i) T (ii) T
C) (i) T (ii) F
D) (i) F (ii) T

Question 5

Decide whether each of these statements is True (T) or False
A belt drive is installed with an initial tension of 400 N in the belt. For a maximum permissible tight side tension of 500 N and the belt moving with a speed of 3 m/s:
(i) The slack side tension will be 100 N.
(ii) The maximum power that can be transmitted is 1200 J.

A) (i) T (ii) T
B) (i) T (ii) F
C) (i) F (ii) T
D) (i) F (ii) F