Questions set 74

Transmission System – Clutches

1.      If there are 7 clutch plates in a multi-plate clutch, what is the number of pair of contact surfaces?
a) 5
b) 4
c) 6
d) 8
Answer: c
Explanation: If ‘n’ is the no. of clutch plates in a multi-plate clutch, then, number of pairs of contact surfaces = ‘n-1’. Therefore no. clutches plates = 7 – 1 = 6.

2.      External diameter of the clutch facing is limited to 120 mm and the inner diameter may be assumed to be 0.3 times the external diameter. Assume uniform wear theory. What is the effective mean radius?
a) 68
b) 58
c) 98
d) 78
Answer: d
Explanation: External diameter = 120 mm. Given Internal diameter = 0.3*external diameter = 0.3 * 120 = 36 mm. Effective mean diameter = (120 + 36) / 2 = 78 mm ⇒ Effective mean radius = 39 mm.

3.      The clutch plate has 160 mm inside and 240 mm outside diameter. The total force provided by the springs is 5 kN, when the clutch is new. The coefficient of friction is 0.4. What is the torque transmitted?
a) 300 Nm
b) 350 Nm
c) 400 Nm
d) 450 Nm
Answer: c
Explanation: inside radius = 80 mm, outside radius = 120 mm ⇒ Effective mean radius = R = (80 + 120) / 2 = 100 mm. Let W = 5 kN = 5000 N and μ = coefficient of friction = 0.4. Torque transmitted = 2 * μ * W * R = 2 * 0.4 * 5000 * 100 = 400 * 10³ Nmm = 400 Nm.

4.      Which of the following contains no linkage between the clutch and the pedal?
a) Clutch – by – wire
b) Wet clutch
c) Hydraulic single plate clutch
d) Hydraulic multi-plate clutch
Answer: a
Explanation: In clutch – by – wire system, there is no mechanical linkage between the clutch and the pedal. The ECU and the actuator control the clutch pedal.

5.      Where is the clutch located?
a) Between transmission and engine
b) Between transmission and rear axle
c) Between transmission and propeller shaft
d) Between transmission and differential
Answer: a
Explanation: The clutch is in the middle of transmission and engine. So that torque can be transmitted from engine to the transmission whenever required.

6.      Which of the following parts of the cover assembly that hold the pressure plate against the clutch plate?
a) Springs
b) Thrust bearings
c) Struts
d) Lever
Answer: a
Explanation: Springs hold the pressure plate against the clutch plate so that pressure can be exerted against the clutch plate and better power transmission can be obtained.

7.      Which of the following is the coefficient of friction of the clutch plate?
a) 1.3
b) 0.8
c) 0.4
d) 0.1
Answer: c
Explanation: The coefficient of friction is always less than 1. Most commonly used material for the clutch plate is ceramic in case of racing cars, heavy loads, etc.

8.     Which of the following is the disadvantage of the cone clutch?
a) It becomes difficult to disengage the clutch when the cone angle is less than 20°
b) It is silent in operation
c) The normal force on the contact surface is larger than the axial force
d) Same torque can be transmitted for the same size as the plate clutch
Answer: a
Explanation: When the cone angle of the cone clutch is less than 20° than the male part of the clutch join the female part and it difficult to disengage the clutch.

9.      The external radius of the cone clutch is 120 mm and the internal radius is 80 mm. The cone angle is kept at 20°. What is the effective mean radius assuming the uniform wear theory?
a) 292 mm
b) 295 mm
c) 100 mm
d) 150 mm
Answer: a
Explanation: r_i = 80 mm, r₀ = 120 mm and θ = 20°. Effective mean radius = (r_i + r_o) / (2*Sin(θ)) = (80 + 120) / (2 * Sin(20°)) = 292.3 mm.

10.  The dry clutch can tolerate longer engagement time than a wet clutch.
a) True
b) False
Answer: b
Explanation: Since metal to oil heat transfer is more effective than the metal to the air, the wet clutch acts as a much better heat exchanger and wet clutch can tolerate longer engagement time.