MCQ on Block Brake
1 - Question
Block brakes are never used in railway trains.
a) True
b) False
View Answer
Answer: b
Explanation: Blocks brakes are commonly employed in railway trains.
2 - Question
If torque capacity of a block brake is 240N-m and radius of drum is 210mm with coefficient of friction 0.4.
a) None of the listed
b) 2857.14N
c) 3443.42N
d) 2334.62N
View Answer
Answer: b
Explanation: N=M/μR.
3 - Question
If initially drum of radius 200mm is rotating at 100rpm, then calculate the heat generated if frictional force acting is 1140N.
a) 3345W
b) 4456W
c) 5969W
d) 11938W
View Answer
Answer: c
Explanation: Heat=Frictional forcexaverage velocity.
4 - Question
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) True
b) False
View Answer
Answer: a
Explanation: The angle of contact is less than 45⁰ and hence the assumption is valid.
5 - Question
The pressure intensity at an element on long shoe brake varies directly with the sin of the pressure angle of the element of friction lining.
a) True
b) False
View Answer
Answer: b
Explanation: p=Cxcos(Ǿ).
6 - Question
The equivalent coefficient of friction in case of block brake with long shoe is denoted by μ[4Sinθ/2θ+sin4θ].
a) True
b) False
View Answer
Answer: b
Explanation: μ[4Sinθ/2θ+sin2θ].
7 - Question
In pivoted block brakes, moment of frictional force about pivot is non zero.
a) True
b) False
View Answer
Answer: b
Explanation: Pivot point is selected such that moment of frictional force about pivot point is zero.
8 - Question
Shoe is constrained to move towards the drum to compensate for the moment acting.
a) Yes
b) It compensates for wear
c) It compensates for both wear and moment
d) None of the listed
View Answer
Answer: b
Explanation: It compensates for the wear which is constant for all points.
9 - Question
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) 321.5mm
b) 314.3mm
c) 289.5mm
d) None of the mentioned
View Answer
Answer: b
Explanation: h=4Rsinθ/2θ+sin2θwhere θ=100/2.
10 - Question
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
View Answer
Answer: b
Explanation: M=2μR²wpsinθ.
11 - Question
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
View Answer
Answer: c
Explanation: R(x)=Rwp(2θ+sin2θ)/2.
12 - Question
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) 2113N
c) 1720N
d) 3440N
View Answer
Answer: d
Explanation: R(y)=μRwp(2θ+sin2θ)/2