1. Anti-Lock Braking Systems
Motor Vehicle Level 3
Resource 1
Anti-Lock Braking Systems 1

2. Aims Motor Vehicle Level 3 Resource 1 To introduce to ABS systems
Anti-Lock Braking Systems
Aims
To introduce to ABS systems 2

3. Objectives At the end of this lesson you should be able to:
Motor Vehicle Level 3 Resource 1
Anti-Lock Braking Systems
Objectives
At the end of this lesson you should be able to:
1. Recognise the reasons for ABS systems within a light Vehicle
2. Identify the main components within an ABS system
3. Explain how an ABS controls the vehicle under heavy braking 3

4. Anti-Lock Braking Systems
Motor Vehicle Level 3 Resource 1
Anti-Lock Braking Systems
Anti-Lock Braking Systems
During emergency braking it can be difficult to control the vehicle due to the wheels locking up
ABS (Anti-lock Braking Systems) prevents the wheels from locking to reduce stopping distances.
Below is an example of a front wheel skid. 4

5. During skidding Motor Vehicle Level 3 Resource 1
Anti-Lock Braking Systems
During skidding
During a skid the skidding wheels have less traction than the non skidding wheels
By preventing the wheels from locking vehicle’s stopping time is reduced
The driver will also be able to control the vehicle under heavy braking 5

6. ABS Components ABS consist of the following components
Motor Vehicle Level 3 Resource 1
Anti-Lock Braking Systems
ABS Components
ABS consist of the following components
Speed Sensors
Valve
Pump
Controller 6

7. Speed Sensors Motor Vehicle Level 3 Resource 1
Anti-Lock Braking Systems
Speed Sensors 7

8. Pump and Valves Motor Vehicle Level 3 Resource 1
Anti-Lock Braking Systems
Pump and Valves
Pumps the brake fluid through the lines
Raises the pressure after it has been released. 8

9. Motor Vehicle Level 3 Resource 1
Anti-Lock Braking Systems
ABS valves
One is included within each brake line controlled by the ABS, there are 3 positions:
Position One: Valve is open and fluid is allowed to pass the brake
Position Two: Valve blocks the line isolating fluid from going to the brake (prevents pressure from rising further)
Position Three: Valve releases some pressure from the brake
The following shows the valve “holding the pressure” at the skidding wheel (Position Two) 9

10. Controller (E.C.U) Motor Vehicle Level 3 Resource 1
Anti-Lock Braking Systems
Controller (E.C.U)
E.C.U (electrical control unit) monitors the speed at all wheels in the vehicle to ensure that they are not under skid.
The ECU also reduces the pressure to the road wheels. 10

11. ABS Operation Motor Vehicle Level 3 Resource 1
Anti-Lock Braking Systems
ABS Operation
The control unit (ECU) will monitor the road wheels for a rapid de-acceleration (a skid is present).
The ECU will then stop brake pressure onto that wheel, allowing the wheel to move again
The ECU will then repeat this until the danger (skid) has passed. 11

12. ABS Types and Layout Motor Vehicle Level 3 Resource 1
Anti-Lock Braking Systems
ABS Types and Layout
Four channel four wheel speed sensor
Three channel three wheel speed sensor
One channel, one wheel speed sensor 12

13. Four channel ABS system (most common)
Motor Vehicle Level 3 Resource 1
Anti-Lock Braking Systems
Four channel ABS system (most common) 13

14. Rise in Popularity in ABS systems
Motor Vehicle Level 3 Resource 1
Anti-Lock Braking Systems
Rise in Popularity in ABS systems 14

15. Summary - Have you? Motor Vehicle Level 3 Resource 1
Anti-Lock Braking Systems
Summary - Have you?
Recognised the reasons for ABS systems within a light vehicle?
Identified the main components within an ABS system?
Explained how ABS controls the vehicle under heavy braking? 15