A pivoted double block brake has a drum radius of 280mm with two shoes subtending an angle of 100⁰. Calculate the distance of pivot from axis of drum.

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

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

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

In a band and block brake, the ratio of tensions on tight side and slack side of the band is (where $$\mu $$ = Coefficient of friction between the blocks and the drum, $$\theta $$ = Semi-angle of each block subtending at the center of drum and n = Number of blocks)

A

$$\frac{{{{\text{T}}_1}}}{{{{\text{T}}_2}}} = \mu \theta {\text{n}}$$

B

$$\frac{{{{\text{T}}_1}}}{{{{\text{T}}_2}}} = {\left( {\frac{{1 - \mu \tan \theta }}{{1 + \mu \tan \theta }}} \right)^{\text{n}}}$$

C

$$\frac{{{{\text{T}}_1}}}{{{{\text{T}}_2}}} = {\left( {\mu \theta } \right)^{\text{n}}}$$

D

$$\frac{{{{\text{T}}_1}}}{{{{\text{T}}_2}}} = {\left( {\frac{{1 + \mu \tan \theta }}{{1 - \mu \tan \theta }}} \right)^{\text{n}}}$$

In a band and block brake, the ratio of tensions on the tight and slack sides of band is given by (where $$\mu $$ = Coefficient of friction between the blocks and the drum, $$\theta $$ = Semi-angle of each block subtending at the centre of drum and n = Number of blocks)

A

$$\frac{{{{\text{T}}_1}}}{{{{\text{T}}_{\text{2}}}}} = \mu \theta \times {\text{n}}$$

B

$$\frac{{{{\text{T}}_1}}}{{{{\text{T}}_2}}} = {\left( {\mu \theta } \right)^{\text{n}}}$$

C

$$\frac{{{{\text{T}}_1}}}{{{{\text{T}}_2}}} = {\left( {\frac{{1 - \mu \tan \theta }}{{1 + \mu \tan \theta }}} \right)^{\text{n}}}$$

D

$$\frac{{{{\text{T}}_1}}}{{{{\text{T}}_2}}} = {\left( {\frac{{1 + \mu \tan \theta }}{{1 - \mu \tan \theta }}} \right)^{\text{n}}}$$

Drum X is 1/2 full of oil and drum Y, which has twice the capacity of drum X, is 2/3 full of oil. If all of the oil in drum X is poured into drum Y, then drum Y will be filled to what fraction of its capacity?

A

3/4

B

5/6

C

11/12

D

7/6

A centrifugal clutch is to transmit 35 kW at 1500 r.p.m. There are four shoes. The speed at which the engagement begins is 0.7 times the running speed. The inside radius of the pulley rim is 120 mm and the centre of gravity of the shoe lies at 80 mm from the centre of the spider. Coefficient of friction may be taken as 0.35. Determine intensity of pressure exerted on the shoes if the angle subtended by the shoes at the centre of the spider is 60° and the width of the shoes is 105.52 mm.

A

109.32 mm

B

186.45 mm

C

150.57 mm

D

105.52 mm

A haulage rope winds on a drum of radius 500 mm, the free end being attached to a truck. The truck has a mass of 500 kg and is initially at rest. The drum is equivalent to a mass of 1250 kg with radius of gyration 450 mm. The rim speed of the drum is 0.75 m/s before the rope tightens. By considering the change in linear momentum of the truck and in the angular momentum of the drum, find the speed of the truck when the motion becomes steady.

A

0.502 m/s

B

0.602 m/s

C

0.702 m/s

D

0.802 m/s

Moment of normal force and frictional forces about the pivot axis are 640000N-mm and 250000N-mm respectively. If force acts at a distance of 190mm from the pivoted point, calculate the actuating force.

A

1078.6N

B

2052.6N

C

3223.5N

D

4454.5N

A weston differential pulley block consists of a lower block and upper block. The upper block has two cogged grooves, one of which has a radius of 150 mm and the other a radius of 125 mm. If the efficiency of the machine is 50% calculate the effort required to raise a load of 1.5 kN.

A

250 N

B

300 N

C

350 N

D

400 N

A pivoted double block brake has a drum radius of 280mm with two shoes subtending an angle of 100⁰. Calculate the distance of pivot from axis of drum.

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