Wall means for a servomotor

Claim 1

A servomotor comprising: a housing having a front shell and a rear shell joined together to form a cavity therein; hub means having a continuous cylindrical body which extends from the interior of said cavity through the rear shell, said cylindrical body having an external periphery with a first ledge located between a first shoulder and a first groove therein and a second ledge located between a second shoulder and a second groove, therein said cylindrical body having an axial bore therein; control valve means located in said axial bore adjacent the rear shell for actuating the servomotor in response to an operator input; reaction means located in said axial bore for transmitting an output force carried through the hub means to an output member; partition means having an outer diameter connected to the housing and an inner diameter which surrounds the cylindrical body between the first shoulder and the second groove to divide the cavity into separate front and rear volumetric arEas; first diaphragm means having an outer diameter secured between the partition means and the rear shell and an inner diameter with a first bead located in the first groove to divide the rear volumetric area into a first vacuum chamber and a first power chamber; first backing plate means abutting a major portion of said first diaphragm means having an outer diameter free to move in said rear volumetric area and an inner diameter with a first sleeve attached thereto and located on said first ledge, said first sleeve having a first face radially compressing the first bead into the first groove to seal the first vacuum chamber from the first power chamber, said first diaphragm means urging a second face of said first sleeve against the first shoulder of the hub means to prevent relative movement therebetween, said first backing plate means responding to a pressure differential created between the first vacuum chamber and the first power chamber upon actuation of said control means to transmit a first axial operational force through the first sleeve into said continuous cylindrical body; second diaphragm means having an outer diameter secured between the partition means and the front shell and an inner diameter with a second bead located in the second groove to divide the front volumetric area into a second vacuum chamber and a second power chamber; second backing plate means abutting a major portion of said second diaphragm means having an outer diameter free to move in the front volumetric area and an inner diameter with a second sleeve attached thereto and located on said second ledge, said second sleeve having a first face radially compressing the second bead into the second groove to seal the second vacuum chamber from the second power chamber, said second diaphragm means urging a second face of said second sleeve against the second shoulder of the hub means to prevent relative movement therebetween, said second backing plate means responding to a pressure differential created between the second vacuum chamber and the second power chamber upon actuation of said control means to transmit a second axial operational force through said second sleeve means into said continuous cylindrical body, said first and second axial operational forces being combined to produce said operational force; and resilient means having one end connected to the front shell and the other end guided by the interior of the cylindrical body into direct engagement with the reaction means for urging the hub means and associated first and second backing plate means and first and second diaphragm means toward the rear shell upon termination of an operator input.