Abstract: A valve assembly including a housing (24?) provided with an inlet port (12?), a delivery port (14?), and an exhaust port (16?), the valve assembly further including a first movable element (32?), a first valve member (34a?) and a second valve member (26a?), the first movable element (32?) being engageable with the first valve member (34a?), engagement of the first valve member (34a?) and first movable element (32?) substantially preventing flow of fluid between the inlet port (12?) and the delivery port (14?), and the first movable element (32?) also being engageable with the second valve member (26a?), engagement of the second valve member (26a?) with the first movable element (32?) substantially preventing flow of fluid between the delivery port (14?) and the exhaust port (16?), the valve assembly further including a second movable element (26?) which divides the housing (24?) into a control chamber (22?) and a main chamber (30?) and which is movable relative to the housing (24?) under the influence of flui

Abstract: A valve assembly including a housing (24?) provided with an inlet port (12?), a delivery port (14?), and an exhaust port (16?), the valve assembly further including a first movable element (32?), a first valve member (34a?) and a second valve member (26a?), the first movable element (32?) being engageable with the first valve member (34a?), engagement of the first valve member (34a?) and first movable element (32?) substantially preventing flow of fluid between the inlet port (12?) and the delivery port (14?), and the first movable element (32?) also being engageable with the second valve member (26a?), engagement of the second valve member (26a?) with the first movable element (32?) substantially preventing flow of fluid between the delivery port (14?) and the exhaust port (16?), the valve assembly further including a second movable element (26?) which divides the housing (24?) into a control chamber (22?) and a main chamber (30?) and which is movable relative to the housing (24?) under the influence of flui

Abstract: A fluid pressure braking system for a vehicle equipped with a drive line retarder automatically reduces the braking pressure level communicated to the brakes controlling the driven wheels of the vehicle to adjust for the retardation effected by the retarder. The retarder is actuated automatically each time the brake is applied by calculating the appropriate retardation level as a function of the brake pressure being demanded by the vehicle operator and by the load carried by the vehicle.