Control apparatus for a brake booster

A control apparatus for a brake system, said control apparatus having a housing with a first bore therein, said first bore being connected with a source of fluid under pressure through an inlet port, a hydraulically operated device through a gear port, a reservoir through a relief port and a brake booster through an outlet port, piston means located in said first bore, said piston means having a first peripheral surface with first and second grooves separated by lands and a second bore, said second bore being connected to said first and second grooves by first and second radial passages, spool means having a second peripheral surface with a control groove thereon located in said second bore and a third bore, said control groove being connected to said third bore by a third radial passage and to said relief port, an input rod located in said third bore, cap means secured to said housing for retaining said piston means in said housing, and resilient means for positioning said piston means within said first bore and said spool means within said second bore whereby pressurized fluid is communicated to said hydraulically operated device by way of said inlet port, first groove, first radial passage, control groove, second radial passage and gear port, said input rod responding to an input force by moving said spool means within said second bore to restrict communication between said first and second radial passages while diverting pressurized fluid to said third bore by way of said third passage, said piston means being characterized by a first projection that extends in sealing engagement with said housing for connecting said third bore with said outlet port to supply said brake booster with pressurized fluid for effecting a brake application.