Abstract: In a pulse modulated servosystem having solenoid activated on-off valves governing the amount of fluid in two variable volume chambers of a double-acting piston-cylinder unit any limitation of the accuracy due to inertia of the valves is eliminated by influencing both chambers in opposite directions.

Abstract: In the prior art, a master brake cylinder is connected to a brake booster by a flange and nut and bolt arrangement. According to the present invention the connection can be made with a reduced number of parts and the large flange of the master cylinder can be eliminated. This is accomplished by providing the connecting end of the master cylinder with a circular groove and the adjacent end of a reinforcing tube of the booster is positioned to encompass the grooved end of the master cylinder, the reinforcing tube having protuberances formed therein to grip the circular groove.