Motor Vehicle Level 3

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

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

3. Motor Vehicle Level 3Resource 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

4. Motor Vehicle Level 3Resource 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.

5. Motor Vehicle Level 3Resource 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

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

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

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

9. Motor Vehicle Level 3Resource 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)

10. Motor Vehicle Level 3Resource 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.

11. Motor Vehicle Level 3Resource 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.

12. Motor Vehicle Level 3Resource 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

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

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

15. Motor Vehicle Level 3Resource 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?