This document discusses various aspects of brakes and braking systems. It covers principles of braking like braking distance, efficiency and weight transfer. It describes different types of brakes based on location, actuation method, construction and application of braking effort. Specific brake types discussed include drum brakes, disc brakes, mechanical brakes, hydraulic brakes and pneumatic brakes. The document also covers topics like master cylinders, antilock braking systems, braking limitations and factors affecting stopping distance.

1. Brakes
&
Braking system
Dr. Chetan S. Mistry

2. BRAKES
• Principle
• Braking distance
• Braking efficiency
• Weight transfer
• Wheel skidding
• Principle and working of various types of brakes
• Anti-lock Brake systems (ABS)

3. Braking requirements:
It MUST
•Stop the vehicle within smallest possible distance.
• Act instantaneously in case of an emergency.
• Strong enough to sustain sudden braking force.
• Neither slip nor should cause any skid the vehicle.
•Brake lining should have longer life.
• Operate with the least effort.

5. Frictional Resistance and Coefficient of Friction
The value of Coefficient of friction depends on several factors:
•Road surface condition.
• Tyre tread pattern.
• Inflation pressure (Correct, over or under –inflated.)
• Material of road surface.

6. Braking Efficiency
Let aBr = Braking retardation
g = Acceleration due to gravity
Highly efficient brakes produce greater deceleration (retardation)
which may cause
• Injury to passenger due to their sudden forward shifting.
• Goods collide among themselves, or collide with driver’s cabin.
• Rapid wear of tyre tread.
• Faster wear of the brake linings and the brake drum.
• Driver to lose control of the vehicle.
As per international standard braking function term is use which is
equal to

7. Stopping distance

8. Braking Effect : Weight transfer

9. Example:
A Maruti car moving at 80kmph takes 32 m to stop when the brakes are applied
on it under standard test conditions. How much is its braking efficiency? Also
determine the retardation produced during braking.
Ans: v=22.2 m/s
BE =87.2 %
deceleration =8.55 m/s2

10. Climbing- up a inclined road

11. Brakes applied to front wheels only

12. Brakes applied to rear wheels only

13. Brakes applied on all the four-wheels

14. Daewoo car has kerb weight of 970 kg and wheelbase of 2520mm. Its CG is 1250
mm in front of the rear axle and 655 mm above the level road. The coefficient of
road-wheels adhesion is 0.6. If the car is moving upward on a road inclined at an
angle of 25 deg with horizontal, calculate the load distribution on the front and rear
axles, the acceleration or retardation, and the stopping distance when, while
moving at 60kmph (1) the front brakes are applied (ii) rear brakes are applied and
(iii) all the four-brakes are applied. The seating capacity of the vehicle is for 5
passengers including driver. Take weight of each person as 600 N.
Ans.
1. RF= 6.76 kN, RR = 5.23kN, Deceleration = 7.28 m/s2, distance = 19.086 m
2. RF= 6.49 kN, RR = 5.01kN, Deceleration = 6.47 m/s2 , distance = 21.47 m
3. RF= 7.50kN, RR = 4.0kN, Deceleration = 9.48 m/s2, distance = 14.656 m

15. Types of brakes
I. On the basis of purpose served
1. Main (Service or primary) operational brakes
2. Parking (or secondary ) brakes
II. On the basis of location in the vehicle
1. Wheel mounted brakes
2. Transmission mounted brakes
III. On the basis of driver’s Ergonomics
1. Foot brakes
2. Hand brakes
IV. On the basis of Actuating method
1. Mechanical brakes
2. Hydraulic brakes
3. Pneumatic brakes (a) Compressed air brakes (b) vacuum brakes
4. Electric brakes

16. V. On the basis of construction
1. Drum brakes
2. Disc brakes
3. Band brakes
VI. On the basis of application of braking effort
1. Manual brakes
2. Servo (power-assisted) brakes
3. Power (power-operated) brakes
VII. On the basis of action of brake shoes
1. Internal expanding brakes
2. External contracting brakes
VIII. On the basis of combinations
1. Drum and disc combination brakes
2. Mechanical and hydro combination brakes
IX. On the basis of speciality
1. Engine exhaust gas operated brake
2. Pneumatic-hydro brake
3. Hill-holding brake

17. Drum brakes : Construction and working

18. Types of drum brakes

19. Articulate anchored type
Floating expander, fixed and
floating anchor type
Types of drum brakes

20. Disc brakes

21. Swinging caliper type Sliding caliper type
Types of Disc brakes

22. Description
1 Life of friction material
2 Visibility of wear from outside
3 Heat dissipation
4 Replacement of friction materials
5 Weight
6 Cooling
7 Water and duct collection
8 Braking effect
Description
9 Temperature effect
10 Self energizing action
11 Brake pedal efforts
12 Behavior of hydraulic system in
released state
13 Force needed to apply brake
14 Nature of wear
15 Shape of friction lining

23. Description Drum brake Disc brake
1 Life of friction material Reasonable
(about 1500 km)
Reasonable
(about 2500 km)
2 Visibility of wear from outside Not possible Can be seen at a
glance
3 Heat dissipation Inferior Better
4 Replacement of friction materials Troublesome and time
taking
Easy and rapid
5 Weight Bulky Lighter
6 Cooling Very slow Efficient
7 Water and duct collection Accumulates Self cleaning
8 Braking effect Generally inconsistent Consistent

24. Description Drum brake Disc brake
9 Temperature effect Severe Unaffected
10 Self energizing action Exists absent
11 Brake pedal efforts Higher Proportional to
retardation
12 Behavior of hydraulic system in
released state
Some pressure
always exists
No hydraulic pressure
on piston
13 Force needed to apply brake Comparatively less More, since brakes are
not self energizing
14 Nature of wear Non uniform Uniform
15 Shape of friction lining Curved Straight

25. Mechanical brakes

26. Hydraulic brakes

27. Types of Master Cylinder
1. Single cylinder
(a)For drum brakes (b) for disc brakes
2. Double master cylinder
3. Tandem master cylinder
Master cylinder

28. Tandem Master cylinder

29. Working

30. Responses when fluid is leaking

31. Conventional braking system Axle by axle split system
Upper and lower wheel cylinder system Diagonal split system

32. Pneumatic brakes

33. Braking limitations

34. Stopping Distance
Sudden Braking

35. Braking on Slippery surface

36. Antilock Braking System
http://www.nhtsa.gov/cars/problems/equipment/absbrakes/page1-doom-04-26-2013.html
http://www.drivingfast.net/technology/abs.htm