Abstract: A servomotor having a partition for separating a first chamber from a second chamber. The partition has a hub with passages therein connecting the first and second chambers with each other and to the atmosphere. The partition has a plurality of concentric annular ribs and radial ribs to strengthen a radial disc that extends from the hub. A valve carried in said hub controls the communication of turbulent free air to the second chamber to create a pressure differential for moving the partition and developing an output force in response to an operator input. This same pressure differential acts on a diaphragm connected to the radial disc to seal a plurality of openings in the radial disc to assure that the pressure differential is not reduced by leakage through the openings.

Abstract: A control valve arrangement for a pressure differential operated servomotor wherein a key member is located in a slot in a hub to retain the control valve and position the control valve in a position to isolate a first chamber from a second chamber in the absence of an input force being applied to operate the valve. The control valve in response to an input force immediately moves to initiate the development of the pressure differential and as a result substantially eliminates the operational time to effect a brake application.

Abstract: A pedal adapter for maintaining the connection between a push rod and a brake lever in a plane perpendicular to and at a fixed radius from a pin. The lever adjacent the pedal adapter is offset at an angle to avoid interference with a stationary member.