Band brake or band and block brake, Theory of Machines(2151902)

1. Gandhinagar institute
of technology(012)
ALAALA
Subject :- TOM(2151902)
Topic name:- Band brake or band and block brake
Prepared by :- jani Parth u. (150120119051)
guided by :- Prof. hardik patel
1

2. content
1. Introduction
2. Type of brake
3. Simple band brake
4. Example
5. Band and block brake
6. Example
2

3. 1. introduction
 Brake is a device which provide artificial frictional resistance is applied
to a moving machine member, in order to stop the motion of a machine
 The brake absorbs either kinetic energy of the moving member or
potential energy given up by objects
 The major functional difference between a clutch and a brake is that a
clutch is used to keep the driving and driven member moving together,
whereas brakes are used to stop a moving member or to control its speed
3

4. 2. Type of brake
4

5. 3. Simple Band Brake
5

6. ...
6

7. 7
µθ
e
T
T
=
2
1
21 TT −
)( 21 TTTB −=
bTPl 1=
bTPl 2=

8. 8

9. 4. Example 1
9
rad713.4
180
270 =
∏
×

10. ...
taking moments about the fulcrum o ,we have
10
225.0)()(225 2121 TTrTT −=−−
NTT 1000225.0/22521 ==−
NT
NT
444
1444
2
1
=
=
bTPl 2=
NP 8.881.04445.0 =×=×
178.1log3.2
2
1
==





µθ
T
T
253.3
2
1
=





T
T

11. ...
(b) Operating force when drum rotates in clockwise direction
11
bTPl 1=
NP 8.288=
4.1441.014445.0 =×=×P

12. 5. Band and Block Brake
 The band brake may be lined with blocks of wood or other material, The friction
between the blocks and the drum provides braking action. Let there are ‘n’ number
of blocks, each subtending an angle 2θ at the centre and the drum rotates in
anticlockwise direction.
1212

13. ...
13

14. ...
Resolving the force radially, we have
Resolving the force tangentially ,we have
14
θµ
θµ
θµ
θµ
θµ
µ
θ
θ
µθ
θ
tan1
tan1
.....
tan1
tan1
)(tan)(
sin)(
cos)(
.cos)(
sin)(
2
1
1
3
1
3
1
2
1
2
1
1
1
1
1
1
1
1
11
1
11
1
11
1
11
1
11
1
11
−
+
=====
−
+
=
+=−
=
+
−
→
=−
−+
−
T
T
T
T
T
T
T
T
T
T
TTTT
RN
RN
TT
TT
RNTT
RNTT
n

15. 15

16. 6. Example 2
16

17. 17

18. 18