Master Brake Cylinder
    (additional information)

The function of the tandem master brake cylinder is to control both brake circuits. Thus, the braking power of one circuit is not affected if the other one breaks down. The pressure-point must still be achieved despite the longer pedal travel, before the pedal reaches the floor. This is why, under normal braking circumstances, a pressure build-up must also occur, even with a short amount of pedal travel. That brake should also completely release, this means, both pistons must also return to their initial positions.

When in the release position, both pistons are near to the compensation ports. In addition, these have a port which is tapered toward the cylinder. This is because their diameter and also the distance that the release- point is from the compensation ports, influences the amount of free pedal travel before the braking actually occurs.

When in the braking position, the two pistons are connected with each other only hydraulically. This ensures an equal pressure distribution between the two brake circuits. Thereby, depending on the brake circuit layout, the piston push-rod (on the right) travels about double the distance that the floating piston (on the left) does.

If the piston push-rod returns to it's initial position because no braking force is being applied, the floating piston, through a shackle- sleeve and screw is also returned. This mechanical connection ensures that, despite the two piston-springs, both pistons are in position just in front of their compensation ports and ready for the next braking operation.

If the brake does no longer release after a longer braking operation, the assumption can be made, that the compensation hole is blocked. 11/11