Abstract: A master cylinder includes a bore communicating with a reservoir and movably receiving a pair of pistons. The pair of pistons cooperate with the housing to substantially form a pair of pressure chambers. An outlet port communicates one of the pressure chambers with a brake circuit and a valve assembly within the outlet port is responsive to the fluid pressure therein to vary communication to the brake circuit. A sleeve within the housing bore movably receives one of the pair of pistons and forms a clearance to communicate the valve assembly with the reservoir independently of the outlet port. The valve assembly is movable in response to a pressure differential between the pair of pressure chambers to close communication between the valve assembly and the reservoir and open communication between the one pressure chamber and the valve assembly independently of the outlet port so as to deactivate the valve assembly. The sleeve also forms an aperture communicating the reservoir with the one pressure chamber.

Abstract: A two stage master cylinder having a bore with a first diameter and a second diameter separated by a shoulder. A first piston is located in the first diameter of the bore to establish a first chamber. A second piston has a first section located in the first diameter of the bore to establish a second chamber and a second section located in the second diameter of the bore to establish an actuation chamber therein. A first passage in the second piston connects the actuation chamber with the second chamber. A second passage in the second piston connects the first passage to a reservoir in the housing. A shuttle piston located in the first passage has a first surface area exposed to the second chamber and a second smaller surface area exposed to the actuation chamber. A spring urges the shuttle piston toward the second chamber. An input force from an operator moves the second piston causing fluid to flow from the actuation chamber through the first passage to the second chamber.

Abstract: A tube seat assembly for retaining a proportioning valve which is located in an outlet port of a master cylinder. The tube seat assembly has a cylindrical body with an axial bore having first, second and third diameter sections. A radial bore is located in the second diameter section adjacent a shoulder which separates the second and third diameter. A sleeve has a first diameter section concentric to said second diameter section of the axial bore and a second smaller diameter section which extends past the shoulder into the third diameter section of the axial bore. A seal surrounds the second diameter section of the sleeve and separates the second diameter section from the third diameter section of the cylindrical body. A spring connected to the cylindrical body urges the sleeve toward the shoulder in the axial bore.

Abstract: A fluid motor having a housing with a stepped bore for retaining a first piston and a second piston. A sleeve is located in the stepped bore to permit the first piston and the second piston to be of substantially the same diameter. A plug attached to the housing holds the sleeve in the stepped bore. A spring attached to the sleeve holds the first piston against a stop. The spring acts on the sleeve to create a gap with a shoulder in the stepped bore. The second piston which is connected to the first piston through a linkage mechanism carries a concentric shuttle piston. The shuttle piston is subjected to a first hydraulic pressure created by the first piston and to a second hydraulic pressure created by the second piston. An indicator is connected to the shuttle piston and remains inactive when the first and second hydraulic pressures are substantially equal.