Hydraulic Braking System
- Primary circuit (1)
- Secondary circuit (2)
- Master cylinder
- Brake control module (BCM)
The hydraulic brake system is a two-circuit diagonal brake system.
The hydraulic brake system is divided up as follows:
The primary circuit (1) includes:
- The front chamber for the master cylinder
- Cylinder in the front left-hand brake caliper
- Cylinder in the rear right-hand brake caliper.
The secondary circuit (2) includes:
- The rear chamber for the master cylinder
- Cylinder in the front right-hand brake caliper
- Cylinder in the rear left-hand brake caliper.
Two brake pipes run from the master cylinder (3) to the brake control module (BCM) (4), where the brake pipes then branch to the wheel brakes.
Servo cylinder
- Vacuum hose connection
- Front push rod
- Membrane spring
- Rubber membrane
- Guide housing
- Push rod spring
- Rear push rod
- Air cleaner (ACL)
- Connecting device EBA
- Reaction disc
- Membrane support.
The vehicle is equipped with a single servo cylinder. It has integrated mechanical brake assistance (EBA). The servo cylinder is located between the brake pedal and the master cylinder and is actuated directly by the brake pedal. It ensures that less pedal force is required when braking with the aid of vacuum from the vacuum pump and via the intake manifold for the engine. The check valve located by the vacuum pump prevents air from flowing back to the servo cylinder.
Mechanical brake assistance (EBA)
- Connecting device.
The mechanical brake assistance (EBA) is integrated in the servo cylinder.
The connecting device (1) is designed as a single unit. It is fully integrated in the servo cylinder and only actuates the standard version of the servo cylinder in the guide housing.
The function can shorten the braking distance considerably, as it is activated when the brake pedal is depressed quickly and firmly.
In such a situation, the ability of the servo cylinder to reinforce the brake force is fully utilized.
Master cylinder
- Push rod (part of primary piston, connected to the servo cylinder)
- Primary circuit chamber
- Valve
- Secondary circuit piston
- Secondary circuit chamber.
The master cylinder is designed for a diagonally split brake system.
One front wheel and one rear wheel are connected together in a circuit. The two chambers in the master cylinder supply one circuit each in the brake system.
The master cylinder is of the tandem type. It contains two pistons, which are connected in series. The master cylinder is actuated by the servo cylinder push rod (1) and brake fluid is pressed into the brake pipes when the brake pedal is pressed. The brake fluid, which is moved in the system, generates an increase in pressure in the wheel brakes causing the vehicle to brake.
There is a valve (3) in the bottom of both pistons. These ensure that the remaining pressure in the chambers (for example after braking using ABS) is released, so that the seals in the master cylinder are not damaged. They also ensure that new brake fluid can be added to the system in the event of wear to brake pads and disc brakes.
For safety reasons, each circuit has a specific piston for pressing the brake fluid out of the master cylinder and into the brake pipes.
Springs in the master cylinder move the pistons back to their resting position when the vehicle is not braking. In this situation the valves are open and both the chambers (brake circuits) are connected to the brake fluid reservoir.
When the brake pedal is pressed, both pistons are moved. The valves are closed and pressure can build up in the brake fluid.
The brake fluid reservoir for the master cylinder ensures that the correct amount of brake fluid is supplied in the system, irrespective of wear to brake pads and disc brakes.