Importance

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Abstract

A control apparatus (12) in a brake system (10) has a housing (20) with an inlet port (26), a gear port (32), a relief port (38), and an outlet port (42). A piston (44) located in a first bore (22) has a first peripheral surface (50) with first (52) and second (54) grooves separated by a land (56) and a second bore (60) respectively connected to the first (52) and second (54) grooves by first (62) and second (64) radial passages. A spool (68) which has a peripheral surface (74) with a control groove (76) is connected to a third bore (88) therein by a cross bore or passage (86) and retained in the second bore (60) by a snap ring (96). An input rod (92) which is located in the third bore (88) has a shoulder (94) which engages the spool (68) while an end cap (98) that is connected to the housing (20) retains the piston (44), spool (68) and input rod (92) in the housing (20). Resilient (104,97) respectively, positioning the piston (44) within the first bore (22) and the spool (68) within the second bore (60) to assure that pressurized fluid is always communicated by way of the inlet port (26), first groove (52), first radial passage (62), control groove (76), second radial passage (64) and gear port (32) to operate the hydraulically operated device (28). The input rod (92) responds to an input force by moving the spool (68) in bore 22 to restrict communication between the inlet port (26) and gear port (32) and diverting pressurized fluid to the outlet port (42) and supply the brake booster (18) with pressurized fluid to effect a brake application.

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First Claim