Brake Booster (BAS), Basic Function - GF42.31-P-2001A

Model all (CAR) 

Shown on model 177.0 

Overview 

This document contains information on:

• Location 
• Tasks 
• Structure 
• Function 

Location 

The BAS brake booster is located on the left in the engine compartment near the traction system hydraulic unit. The traction system hydraulic unit is located on the left front of the engine compartment between the firewall and the heat shield.

Tasks 

The BAS brake booster supports the pedal force applied by the driver during braking.

Structure 

The BAS brake booster contains the following components:

• Brake vacuum sensor
• Position sensor
• Solenoid
• Indicator switch

Function 

The BAS brake booster is supplied with vacuum by a vacuum line either from the electric vacuum pump, the combustion engine or the mechanical vacuum pump. If the brake is not operated, equal vacuum exists on both sides of the diaphragm. A compression spring holds the diaphragm plate in its starting position.

The travel sensor is designed as a potentiometer. It records both the pedal movement as well as the diaphragm movement of the brake booster.

If a high actuation speed (emergency braking) is detected, the solenoid is actuated. The work chamber of the brake booster is ventilated; the full boosting can take effect. Maximum full-stop braking takes place even if the pedal pressure implemented by the driver is insufficient. ABS regulation prevents the wheels from locking up. If the brake pedal is fully released, the indicator switch switches off the solenoids. Brake force boosting is completed.

	Components
	Brake vacuum sensor, basic function		GF42.31-P-2002A