Abstract: A check valve is disclosed for permitting a fluid flow in a generally one direction. The check valve is provided with an elongated housing with a central passageway within which a valve member moves for permitting a fluid flow in one direction and for closing a fluid communication when moving in an opposite direction. The valve member has a conically-shaped groove for receiving a sealing member therein. When the sealing member becomes expanded under the influence of fluids passing through the check valve, it is allowed to move from the groove along a neck of the valve member. The interior wall housing is provided with plurality of longitudinal grooves extending in parallel relationship to a central axis of the housing in that part of the housing wherein the valve member moves. The longitudinal grooves ensure fluid flow through the valve member at all times.

Abstract: A pilot control valve comprising an elongated valve member shiftable within a valve body between a first and a second position. The first position allows communication of control fluid to a first pressure receiving surface to initiate movement of the valve member from its first position to a position equalizing the pressure acting on a second pressure receiving surface with the pressure of the control fluid, thereby causing the valve member to move to its second position. The valve member when in its second position allows communication with a third pressure receiving surface for initially moving the valve member from its second position while equalizing the pressure acting on the second pressure receiving surface to move the valve member to a position equalizing the pressure acting on the second pressure receiving surface with a pressure lower than the pressure of the control fluid for moving the valve member to its first position whereby the operation is repeated at infinitum.

Abstract: A pilot control relay valve having first and second elongated valve members coaxially and independently longitudinally shiftable within a valve body between a first position of the first or leading valve member thereby allowing communication of actuating fluid from a supply to a first pressure receiving surface of the second or following valve member to initiate movment of the second valve member from its first position to a second position thereby allowing communication of the actuating fluid to a first pressure receiving surface of a main piston to initiate movement of the first valve member to a second position of the first valve member thereby allowing communication of supply fluid to the second pressure receiving surface of the second valve member thereby initiating movement of the second valve member from its second to its first position thereby allowing communication of supply fluid to a second pressure receiving surface of the main piston to initiate movement of the first valve member to its first pos