Chevrolet Cobalt Service & Repair Manual: Description

Chevrolet Cobalt Service & Repair Manual / Brakes / Power Brake Units / Description

AC-Delco Tandem Diaphragm Type

This unit utilizes a vacuum power chamber, consisting of a front and rear shell, housing divider, front and rear diaphragm, plate assemblies, hydraulic pushrod and a diaphragm return spring, Fig. 1.

In normal operating mode, with service brakes in released position, the booster operates with vacuum on both sides of its diaphragms. When brakes are applied, air at atmospheric pressure is admitted to one side of each diaphragm to provide power assist. When the service brake is released, atmospheric air is shut off from one side of each diaphragm. The air is then drawn from the booster through the vacuum check valve to the vacuum source.

GM/Toyota Single Diaphragm Type

The Toyota/GM single diaphragm type booster assembly is located between the master cylinder and brake pedal, Fig. 2. When the brake pedal is depressed, the force is transmitted to the master cylinder piston through the valve operating rod, booster air valve, reaction disc and piston rod. The force of the booster piston is developed because of the pressure difference between the front and rear chambers.

Fig. 1 Exploded view of AC-Delco tandem diaphragm booster

Fig. 2 Exploded view of GM/Toyota brake booster

Adjustments

Brake Pedal 1. With ignition OFF and brakes cool, apply brakes three or four times, or until brake pedal becomes firm, in order to deplete brake booster power ...

General Service

Two basic types of power assist mechanisms are used: vacuum assist diaphragm assemblies, which use engine vacuum or in some cases vacuum pressure developed by an external vacuum pum ...

Chevrolet Cobalt Service & Repair Manual: Description

Adjustments

General Service

See also:

Chevrolet Cobalt Owners Manual

Chevrolet Cobalt Service Manual