Abstract: A pressure relief valve is disclosed. The pressure relief valve comprises a valve housing including fluid passageways, a poppet valve disposed within the housing, a piston disposed within the housing, and spring means disposed intermediate the piston and the poppet valve for biasly urging apart the piston and the poppet valve. The poppet valve has a valve seat which, together with a portion of the housing, defines a variable valve area. The piston has a piston area, relatively greater than the variable valve area, for modulating flow through, and pressure drop across, the poppet valve. The pressure relief valve preferably includes an orifice disposed within the housing for selectively controlling flow of hydraulic fluid through the housing passageways to the piston. The housing preferably includes an elongated cage within which the poppet valve is longitudinally slidable.

Abstract: A novel flow divider-combiner valve unit is disclosed. A valve body includes fluid passageway means for controlling fluid flow through the divider-combiner valve unit. The fluid passageway means comprises: a cavity, first, second and third passageways; first and second pressure-responsive elements; and biasing elements for retaining the pressure-responsive elements substantially in open positions until a predetermined substantial pressure differential exists in the divider-combiner valve unit. The biasing elements also enable the pressure-responsive elements to move substantially independently of each other toward closed positions when a first pressure differential in the divider-combiner valve unit exceeds the predetermined pressure differential. The biasing elements additionally cause the pressure-responsive elements to move substantially in unison when a second pressure differential in the divider-combiner valve unit exceeds the predetermined pressure differential.

Abstract: There is disclosed a new and improved hydraulic sequencing valve of the type which includes a movable valve spool within the body to sequence operation of the valve. An aperture through one spool or chamber is arranged for direct fluid communication with a tank port upon initial movement of the spool to increase the differential fluid pressure across the chambers and accelerate the sequencing movement of the spool.

Abstract: A hydraulic sequencing valve is disclosed. A hollow spool is slidably carried in a valve body for motion between a first position in which fluid is caused to flow out a valve first port and a second position in which fluid is caused to flow into the first port. An annular partition is provided within the spool hollow, which divides the spool hollow into two chambers. When a pressure rise is experienced within the spool, a pre-set valve element trips, reducing pressure within one spool chamber. This pressure change shifts the spool to a second position. A check valve is provided in a separate valve body conduit. This check valve operates to assure that the valve spool remains in its second position until the valve and associated hydraulic system have completed the full cycle of operation.

Abstract: A counterbalance valve assembly for use in a hydraulic system of the type including a hydraulic cylinder for raising and lowering a load provides gradual and continuous exhaustion of hydraulic fluid from the cylinder to facilitate smooth lowering of the load. The assembly includes a counterbalance valve having an outer barrel and an inner barrel forming an annular channel therebetween through which the exhausted fluid passes. The outer barrel includes an inner valve seat and the inner barrel includes an outer relief valve surface which engages in the annular channel to form a relief valve. The inner barrel is movable in a linear direction within the outer barrel for opening and closing the relief valve as the load is lowered. To avoid abrupt changes in the exhausted cylinder fluid flow rate, and thus to avoid abrupt variations in the load lowering rate, the relief valve surface has a long tapered configuration rendering the exhausted fluid flow rate less sensitive to inner barrel movement.

Abstract: A fluid flow control valve assembly provides metering of the hydraulic fluid from a cylinder port at a constant desired rate for lowering a load at a corresponding constant rate which has been raised by the cylinder. The valve assembly comprises a normally closed valve having an input orifice communicating with the cylinder port and an output orifice and is selectively actuable for permitting the flow of fluid from the cylinder. A normally closed pressure compensating valve has an input orifice communicating with the normally closed valve output orifice, an output orifice, and a control input adapted for direct communication with the cylinder port for continuously sensing the fluid pressure within the cylinder. The pressure compensating valve maintains a constant fluid flow pressure differential and a constant fluid flow rate from the cylinder.

Abstract: A modular hydraulic valve is disclosed, which comprises a valve manifold and a number of valve cartridge elements disposed at least partly within cavities defined in the valve manifold. To encourage interchangeability and reduce manufacturing costs, each cavity includes a number of axially aligned steps of progressively decreasing diameter. The outermost steps of each cavity is defined by a diameter identical with the outermost step diameter of all other cavities, regardless of whether those other cavities define one or more than one additional steps. Likewise, the second outermost step in each cavity is defined by another diameter which is substantially identical with the second step diameter of all other cavities having two or more steps.