Fluid pressure operated servomotor

Claim 1

A fluid pressure operated servomotor comprising: a main body; a diaphragm and a power piston coacting to divide the interior of said main body into front and rear airtight chambers; a valve mechanism positioned in said power piston for controlling the pressure in at least one of said chambers; an input shaft connected to said valve mechanism for actuating said valve mechanism; an output rod means in said front chamber for transmitting the force of said power piston; a retaining plate mounted on the surface of said power piston facing said front chamber and having cut-outs therein extending radially outwardly; a plurality of reaction levers extending through respective cut-outs for being positioned on said power piston with the extremities of the radially inner end towards said rear chamber from said retaining plate and intermediate portions of the radially inner ends exposed toward said front chamber and the radially outer ends exposed toward said front chamber from said retaining plate, said retaining plate having fulcrums on a side toward the front chamber engaged by the respective reaction levers and about which said reaction levers pivot between one position in which the intermediate portions of the radially inner ends are engaged only with said output rod means for transmitting an output force from said power piston to said output rod means and a second position in which the extremities of the inner ends are engaged with said input rod for transmitting a reaction force to said input shaft and a return spring in said front chamber engaging the radially outer ends of said levers for biasing said power piston rearwardly.