In a block brake with short shoe, it is assumed that friction force and normal reaction are concentrated at the midpoint of the shoe.

A centrifugal clutch has four shoes. When the clutch is at rest, each shoe is pulled against a stop by a spring so that it leaves a radial clearance of 10 mm between the shoe and the rim. The pull exerted by the spring is then 700 N. The mass centre of the shoe is 150 mm from the axis of the clutch. If the internal diameter of the rim is 500 mm, the mass of each shoe is 6 kg, the stiffness of each spring is 75 N/mm and the coefficient of friction between the shoe and the rim is 0.35; find the power transmitted by the clutch at 400 r.p.m.

A

3.439 kW

B

34.39 kW

C

3439 kW

D

3.439 W

A centrifugal clutch has four shoes. When the clutch is at rest, each shoe is pulled against a stop by a spring so that it leaves a radial clearance of 7.5 mm between the shoe and the rim. The pull exerted by the spring is then 600 N. The mass centre of the shoe is 120 mm from the axis of the clutch. If the internal diameter of the rim is 350 mm, the mass of each shoe is 5 kg, the stiffness of each spring is 60 N/mm and the coefficient of friction between the shoe and the rim is 0.2; find the speed of the centrifugal clutch, if the power transmitted is 40.168 kW.

A

83.779 r.p.m.

B

800 r.p.m.

C

104.66 r.p.m.

D

1000 r.p.m.

What is the braking torque at leading shoe if resultant frictional force acts at a distance of 250 mm from the brake drum center, coefficient of friction between the shoe and the drum as 0.5, the free ends of the two shoes are pushed apart with a force of 300 N which is acting at a distance of 320 mm from anchor, and two shoes are anchored together 170 mm away from the brake drum center?

A

276.6 Nm

B

256.6 Nm

C

266.6 Nm

D

246.6 Nm

For a shoe brake, the equivalent coefficient of friction is equal to (where $$\mu $$ = Actual coefficient of friction and $$\theta $$ = Semi-block angle)

A

$$\frac{{2\mu \sin \theta }}{{\theta + \sin \theta }}$$

B

$$\frac{{\mu \sin \theta }}{{2\theta + \sin 2\theta }}$$

C

$$\frac{{4\mu \sin \theta }}{{\theta + \sin \theta }}$$

D

$$\frac{{4\mu \sin \theta }}{{2\theta + \sin 2\theta }}$$

A pivoted double block brake has a drum radius of 280mm with two shoes subtending an angle of 100⁰. Maximum pressure intensity is 0.5N/mm². If the width of friction lining is 90mm, find the torque capacity f each shoe. Assume coefficient of friction as 0.2.

A

789N-m

B

1081N-m

C

945N-m

D

None of the listed

Pyroxenes are class of silicate minerals, which exhibit a polymeric chain structure, as shown below
S-Block and P-Block Elements mcq question image

S-Block and P-Block Elements mcq question image

Its simplest repeating unit is

A

^4-

B

^2-

C

^6-

D

^6-

A spring block system is on a horizontal surface. The block is compressed by 10cm. What should be the coefficient of friction between the block and ground such that the block comes to a stop at the mean position? Mass of block = 0.5kg & spring constant = 3N/m.

A

0.03

B

0.06

C

0.12

D

0.05

A single cylinder, four stroke cycle oil engine is fitted with a rope brake. The diameter of the brake wheel is 600 mm and the rope diameter is 26 mm. The dead load on the brake is 200 N and the spring balance reads 30 N. If the engine runs at 450 r.p.m., what will be the brake power of the engine?

A

2 kW

B

2.5 kW

C

3 kW

D

3.5 kW

A pivoted double block brake has a drum radius of 280mm with two shoes subtending an angle of 100⁰. Maximum pressure intensity is 0.5N/mm². If the width of friction lining is 90mm, find the reaction at pivot in horizontal direction. Assume coefficient of friction as 0.2.

A

None of the listed

B

21123N

C

17200N

D

16789N

The equivalent coefficient of friction in case of block brake with long shoe is denoted by μ.

A

. ] True

B

4Sinθ/2θ+sin4θ

C

4Sinθ/2θ+sin4θ

D

4Sinθ/2θ+sin4θ

In a block brake with short shoe, it is assumed that friction force and normal reaction are concentrated at the midpoint of the shoe.

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