Abstract: A hydraulic pressure control valve, such as a pilot-operated relief valve and such as a direct-acting differential piston relief valve, having a spring chamber pressurized with fluid from a passage though a movable relief piston. The fluid within the spring chamber may be at the same pressure as that at the inlet valve closing pressure to assist a coil spring acting against the inner face of the relief piston. Inlet pressure in the valve working on an area difference between the faces of the relief piston produces the hydraulic force which is opposed by the spring to open the valve. At its other end, the spring transmits force against a movable biasing piston immediately adjacent a closed end of the spring chamber. The biasing piston provides automatic linearly increasing adjustment of the set pressure in response to inlet pressure acting over a greater net area than that of the relief piston.

Abstract: Two pressure control valves have most components in common. One valve is a direct-acting sequence valve and the other a vented counterbalance valve with pilot assist. Both valves have a set opening pressure which is insensitive to secondary port pressure. Both valves may provide free reverse flow. The valves include a spring force reduction chamber which receives hydraulic fluid at primary port pressure. Part of the opening force exerted at the primary port is offset by pressure in the spring force reduction chamber so that a spring having a smaller spring constant may be used to resist opening force. This offsetting force may be readily modified by changing the diameter of the piston shaft of the valve.

Abstract: A direct-acting, differential piston relief valve has a spring chamber pressurized with fluid from a passage through the piston. The fluid within the chamber is at the same pressure as that at the inlet valve and provides a valve closing pressure against the inner face of the piston. The piston face at the inlet valve has an annular extension. The inner circumference of this extension meets the spherical valve seat when the valve is closed. The diameter of the inner face of the piston is smaller than the diameter of the piston face annular extension. Inlet pressure working on this area difference produces the hydraulic force which is opposed by the spring. No piston face area is exposed to forces tending to close the valve due to Bernoulli effects when the valve begins to open. The spring within the spring chamber has spring guides at each end which contain a ball. The ball transmits the spring force to the piston on one end and a sealed closure at the other end.

Abstract: A flow regulator valve has a first fluid opening at one end and a second fluid opening at the side of the valve body. A sleeve bore extends from the first opening and contains a stem which is co-axial with the sleeve bore, but spaced from it. A compensating spool is slideably mounted between the sleeve bore and the stem and may move to completely close the second opening or to provide partial opening. A control spring biases the spool to the open position, but a fluid passage through the stem wall permits the pressure of the fluid at the first opening to be applied to bias the spool to the closed position. A valve element containing an orifice establishes the nominal flow rate desired, while the pressure drop across the spool causes it to assume a position to maintain the desired flow rate. A valve element control spring may be used to maintain the valve element in the "off" position until the pressure rises to a desired threshold. Venting of the cavity in which the valve element is located is provided.

Abstract: A calibrated handknob assembly for use with a valve having a control stem, said assembly having a rising stem with spaced circumferential calibrations, a handknob having circumferentially spaced radial calibrations, a lock ring having an index cooperating with said handknob calibrations and having positions for permitting setting of the handknob "zero" position and index position at a desired circumferential location, for placing the assembly in a condition where the handknob cannot be rotated and for permitting rotation of the handknob to change the valve opening. An O-ring is used to detent the lock ring so that inadvertent rotation of the handknob will not occur and to prevent movement of the lock ring to the position where the handknob can be removed and "0" calibration reset. The O-ring may be easily removed to permit the resetting when needed.