Abstract: A lever arrangement for providing a servomotor in a power braking system with a variable operational output force. The servomotor has a wall moved by a pressure differential to create an initial output force. The lever arrangement is attached to the servomotor and modifies the initial output force from the wall to create the variable operational output force which is supplied to a master cylinder.

Abstract: Improvements in a servomotor including a retainer coupling an annular diaphragm having its outer periphery sealingly attached to the servomotor housing and an axially movable power piston within the housing. The piston has a boss axially extending through the annular diaphragm and an external flange extending radially from the outer periphery of the boss for positioning adjacent the diaphragm, the diaphragm and power piston forming two pressure chambers. A valve member is slidably and sealingly disposed in a bore formed in the boss of the power piston for regulating pressure in the pressure chambers. The retainer has an axially extending cylindrical seat in which the boss is tightly positioned and a flange radially extending from the seat for pressing an inner portion of the diaphragm against the power piston flange.