1. Axial operation claw clutches having selflocking tooth profile
(a) Can be disengaged at any speed
(b) Can be disengaged only unloaded
(c) Can be engaged only when unloaded
(d) Can work only with load
(1 Mark, 1987)

Ans: a
Axial operation claw clutches having self locking tooth profile can be disengaged at any speed.
2. A wire rope is designated as 6 × 19 standard hoisting. The numbers 6 × 9 represent
(a) Diameter in millimeter × length in meter
(b) Diameter in centimeter × length in meter
(c) Number of strands × number of wires in each strand
(d) Number of wires in each strand × number of strands
(1 Mark, 2003)

Ans: c
3. In a band brake the ratio of tight side band tension to the tension on the slack side is 3. If the angle of overlap of band on the drum is 180° the coefficient of friction required between drum and the band is
(a) 0.20
(b) 0.25
(c) 0.30
(d) 0.35
(1 Mark, 2003)

Ans: d
Statement for Linked Questions.
A band brake consists of a lever attached to one end of the band. The other end of the band is fixed to the ground. The wheel has a radius of 200 mm and the wrap angle of the band is 270°. The braking force applied to the lever is limited to 100N, and the coefficient of friction between the band and the wheel is 0.5. No other information is given.
4. The maximum tension that can be generated in the band during braking is
(a) 1200 N
(b) 2110 N
(c) 3224 N
(d) 4420 N
(2 Mark, 2003)

Ans: b
5. The maximum wheel torque that can be completely braked is
(a) 200 N.m
(b) 382 N.m
(c) 604 N.m
(d) 844 N.m
(2 Mark, 2005)

Ans: b
6. A disk clutch is required to transmit 5 kW at 2000 rpm. The disk has a friction lining with coefficient of friction equal to 0.25. Bore radius of friction lining is equal to 25 mm. Assume uniform contact pressure of 1 MPa. The value of outside radius of the friction lining is:
(a) 39.4 mm
(b) 49.5 mm
(c) 97.9 mm
(d) 142.9 mm
(2 Mark, 2006)

Ans: a
7. A blockbrake shown below has a face width of 300 mm and a mean coefficient of friction of 0.25. For an activating force of 400 N, the braking torque in Nm is
(a) 30
(b) 40
(c) 45
(d) 60
(2 Mark, 2007)

Ans: c
8. A clutch has outer and inner diameters 100 mm and 40 mm respectively. Assuming a uniform pressure of 2 MPa and coefficient of friction of liner material 0.4, the torque carrying capacity of the clutch is
(a) 148 Nm
(b) 196 Nm
(c) 372 Nm
(d) 490 Nm
(2 Mark, 2008)

Ans: b
9. A band brake having bandwidth of 80mm, drum diameter of 250mm, coefficient of friction of 0.25 and angle of wrap of 270 degrees is required to exert a friction torque of 1000Nm. The maximum tension (in kN) developed in the band is
(a) 1.88
(b) 3.56
(c) 6.12
(d) 11.56
(2 Mark, 2010)

Ans: d
10. A force of 400 N is applied to the brake drum of 0.5 m diameter in a bandbrake system as shown in the figure, where the wrapping angle is 180°. If the coefficient of friction between the drum and the band is 0.25, the braking torque applied, in N.m is
(a) 100.6
(b) 54.4
(c) 22.1
(d) 15.7
(2 Mark, 2012)

Ans: b
11. A disc clutch with a single friction surface has coefficient of friction equal to 0.3. The maximum pressure which can be imposed on the friction material is 1.5 MPa. The outer diameter of the clutch plate is 200 mm and its internal diameter is 100 mm. Assuming uniform wear theory for the clutch plate, the maximum torque (in N.m) that can be transmitted is _______.
(2 Mark, 2014[2])

Ans: 530.14
12. A fourwheel vehicle of mass 1000 kg moves uniformly in a straight line with the wheels revolving at 10 rad/s. The wheels are identical, each with a radius of 0.2 m. Then a constant braking torque is applied to all the wheels and the vehicle experiences a uniform deceleration. For the vehicle to stop in 10 s, the braking torque (in N.m) on each wheel is
(2 Mark, 2014[3])

Ans: 10
13. A drum brake is shown in the figure. The drum is rotating in anticlockwise direction. The coefficient of friction between drum and shoe is 0.2. The dimensions shown in the figure are in mm. The braking torque (in N.m) for the brake shoe is _____.
(2 Mark, 2014[3])

Ans: 64
14. The forces F_{1} and F_{2} in a brake band and the direction of rotation of the drum are as shown in the figure. The coefficient of friction is 0.25. The angle of wrap is 3π/2 radians. It is given that R = 1 m and F_{2} = 1 N. The torque (in Nm) exerted on the drum is ____.
(1 Mark, 2016[2])

Ans: 2.248
15. For the brake shown in the figure, which one of the following is TRUE?
(a) Self energizing for clockwise rotation of the drum
(b) Self energizing for anticlockwise rotation of the drum
(c) Self energizing for rotation in either direction of the drum
(d) Not of the selfenergizing type
(1 Mark, 2016[2])

Ans: a
16. A single plate clutch has a friction disc with inner and outer radii of 20 mm and 40 mm, respectively. The friction lining in the disc is made in such a way that the coefficient friction μ varies radially as μ = 0.01r, where r is in mm. The clutch needs to transmit a friction torque of 18.85 kN mm. As per uniform pressure theory, the pressure (in MPa) on the disc is ______.
(2 Mark, 2017[2])

Ans: 0.5
17. The schematic of an external drum rotating clockwise engaging with a short shoe is shown in the figure. The shoe is mounted at point Y on a rigid lever XYZ hinged at point X. A force 𝐹 = 100 𝑁 is applied at the free end of the lever as shown. Given that the coefficient of friction between the shoe and the drum is 0.3, the braking torque (in Nm) applied on the drum is _______ (correct to two decimal places).
(2 Mark, 2018[1])

Ans: 8.18
18. A single block brake with a short shoe and torque capacity of 250 Nm is shown. The cylindrical brake drum rotates anticlockwise at 100 rpm and the coefficient of friction is 0.25. The value of a, in mm (round off to one decimal place), such that the maximum actuating force P is 2000 N, is _____.
(2 Mark, 2019[1])

Ans: 212.5
19. A short shoe external drum brake is shown in the figure. The diameter of the brake drum is 500 mm. The dimensions a = 1000 mm, b = 500 mm and c = 200 mm. The coefficient of friction between the drum and the shoe is 0.35. The force applied on the lever F = 100 N as shown in the figure. The drum is rotating anticlockwise. The braking torque on the drum is ____ Nm (round off to two decimal places).
(2 Mark, 2019[2])

Ans: 20.34