Abstract: A hydraulic cylinder comprises a piston reciprocally mounted in a housing thereof. A pair of annular sealing means, slidably receiving a rod of the piston, are disposed on either side of an annular chamber which has pressurized fluid pumped therethrough for flushing purposes.

Abstract: A method and plural embodiments of apparatus for delivering a pressure-compensated supply of fluid to a hydraulic steering circuit, wherein first and second pumps are respectively operated by a vehicle engine and by a ground wheel when the vehicle is in motion, output fluid from the two pumps being simultaneously directed to the steering circuit by a control valve with inlet relief valve means modulating output pressure of the sources in response to operation of the control valve. One embodiment contemplates dual inlet relief valves for separately modulating output from the two pumps while another embodiment contemplates one of the pumps having a variable output.