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

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

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

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

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

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

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

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

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

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

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

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

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

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

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