INTRODUCTION - BRAKE VACUUM SYSTEM

CONSTRUCTION SPECIFICATIONS

The vacuum braking system consists of an intake manifold - which supplies the necessary vacuum (with the engine running) for the operation of the brake servo to which it is connected by a pipe - and the pump, also known as the master cylinder, fitted on the brake servo.

For JTD engines, the vacuum braking system consists of a vacuum pump. This supplies (with the engine running) the necessary vacuum for the operation of the brake servo to which it is connected by a pipe, and of the control pump, also known as the master cylinder, fitted on the brake servo.

The pump is connected by two pipes, each of which supplies a section of the crossover circuit, to the ABS electro-hydraulic control unit.

See

See descriptions 3340 ANTI-LOCK BRAKING SYSTEM (ABS)

On versions equipped with the ESP function, the pump and the control unit supply pipes are larger because this type of system has a greater fluid capacity.

OPERATION

The system offers smoother, more powerful braking through the action of the brake servo. The brake servo is a pneumatic device that powers the brake pedal action on the pump and enables better braking modulation by using the available vacuum effect (with the engine running) in the intake manifold for petrol engines or in the vacuum pump for JTD engines.

If there is a fault in the vacuum system (or if the engine is not running), braking system operation is guaranteed because the connection between the pedal and the brake pump remains operational.

In these emergency conditions, the brake pedal becomes very difficult to operate and the braking system does not maintain the same responsiveness, so it is therefore advisable to drive very carefully to the nearest authorised workshop to have the system checked.