XJ-6 L6-4.0L (1991)
Brake Master Cylinder: Description and Operation
Master Cylinder
ABS Brake Master Cylinder
MASTER CYLINDER
The master cylinder acts exclusively on the front wheel brakes, the static circuit. The pressure in the master cylinder is generated by means of force
acting from the booster piston to static fluid column.
In addition, the positioning sleeve and the main valve are integrated in the master cylinder.
The brake pressure to the rear wheel brakes is supplied by the hydraulic accumulator through the control valve.
Master Cylinder
As pressure is applied to the brake pedal, the master cylinder piston (1) is moved forward by the booster piston (5). The central valve (2) closes and a
pressure is built up in the front wheel brakes. Simultaneously to the forward movement of the booster piston the positioning sleeve (3) is pulled to the
left. The main valve (4) is in an inoperative position. The connection between the master cylinder and the reservoir is open, the connection between
the booster and the master cylinder is closed.
Should there be a wheel locking tendency during braking at one or more front wheels, the main valve (4) is controlled by the electronic control
module. The main valve closes the connection between the static circuit of the master cylinder and the reservoir.
Simultaneously, the connection between the dynamic circuit in the rear wheel brakes the booster, and the static circuit in the front wheel brakes is
made.
The dynamic pressure is applied to the positioning sleeve (3) which is moved to its stopping point. This movement causes the push back of the
booster piston and of the pedal. At the same time, the dynamic flow-in over the primary seal (6) of the master cylinder piston (1) and thus the direct
pressure supply in the wheels occurs.
The pressure on the right side of the primary seal is higher than on the left side and due to this the primary seal is pushed forward.
Due to the pressure compensation, the master cylinder piston (1) is pushed to the booster piston (5).
The direct flow into the front wheel brakes and the push back of the pedal, avoids a pedal pulsation during braking under ABS control and guarantees
at the same time that sufficient reserve is available in case of rear circuit failure.
