# Block Brake Machine Design MCQs

Suppose we have a pivoted double block brake. The drum radius is 280mm and with two shoes delimitating an angle of 100⁰. Suppose that the maximum pressure intensity is 0.5N/mm². Calculate the reaction at pivot in the horizontal direction, if the width of the friction lining is 90mm. You can suppose the coefficient of friction is 0.2. Select the most suitable answer.

(A). None of the above

(B). 2550N

(C). 3440N

(D). 1720N

“The pressure intensity at an element on a long shoe brake varies directly with the sin of the pressure angle of the element of friction lining”.

(A). False

(B). True

(C). (Partially True)

Select the status for the “The equivalent coefficient of friction in case of block brake with the long shoe is denoted by μ[4Sinθ/2θ+sin4θ].”

(A). False

(B). True

(C). (Partially True)

In pivoted block brakes, the moment of a frictional force about the pivot is non zero.

(A). False

(B). True

(C). (Partially True)

The shoe is constrained to walk with respecting the drum to compensate for the moment act.

(A). Yes

(B). It compensates for both wear and moment

(C). It compensates for wear

(D). None of the above

The Answer is: (C). It compensates for wear

Suppose we have a pivoted double block brake. The drum radius is 280mm with two shoes delimitating an angle of 100⁰. You need to calculate the distance of pivot from the axis of the drum. Select the most suitable answer.

(A). 314.3mm

(B). 317.5mm

(C). 218.5mm

(D). None of the above

Select the status for the following “Block brakes are never used in railway trains”.

(A). False

(B). True

(C). (Partially True)

When the torque capacity of a block brake is 240N-m and the radius of the drum is 210mm with a coefficient of friction 0.4.

(A). None of the above

(B). 3443.42N

(C). 2857.14N

(D). 2334.62N

Suppose that the frictional force acting is 1140N. When starting drum of radius 200mm is rotating at 100rpm, then select the best answer that how much heat will produce?

(A). 3345W

(B). 4456W

(C). 11938W

(D). 5969W

Suppose we have a pivoted double block brake The drum radius is 280mm with two shoes delimitating an angle of 100⁰. Suppose that the maximum pressure intensity is 0.5N/mm². Calculate the reaction at pivot in the horizontal direction, if the width of the friction lining is 90mm. You can suppose the coefficient of friction is 0.2. Select the most suitable answer.

(A). None of the above

(B). 17200N

(C). 18200N

(D). 19200N