Abstract: A hydraulic system has high priority hydraulic functions connected to a primary supply line that receives pressurized fluid from a source and low priority hydraulic functions connected to secondary supply line. A priority valve couples the primary supply line to the secondary supply line. The priority valve detects when the source is unable to furnish enough pressurized fluid to satisfy the demands of all the high and low priority hydraulic functions. In that case the priority valve reduces or eliminates fluid flow between the primary and secondary supply lines.

Abstract: An improved bidirectional plug valve with increased C.sub.v or decreased insertion pressure loss is provided. The improvements reside in a unique combination of surprising structural parameters including an increase in the diffuser-to-dump transition radii, a high degree of dimension match for diffuser and plug chamber, an unconventionally large diffuser angle, and most surprisingly, a reduction in plug port size with a substantial corresponding reduction in plug size and dump area. The indicated structural features of the invention, combine synergistically to provide an unexpected C.sub.v improvement of approximately 50% and a substantial cost reduction for the valve operating mechanism.

Abstract: A linear retractable seal valve having a wedge sealing-slip assembly slideably held at opposite side edges of the wedge to guide rails of the valve body and moveable from a distant first location to a second location between inlet and outlet ports of the valve from which latter location the sealing slips are wedged outwardly of the longitudinal movement of the assembly into closure engagement with the valve ports, with the valve being returned to its open position through a reverse sequential movement wherein there is first a perpendicular movement of the slips out of closure engagement with the valve ports, following which there is a reverse longitudinal movement of the wedge-slip assembly away from the fluid passageway to its valve open first location.

Abstract: A linear retractable seal valve having an inlet and outlet port and a fluid passageway therebetween with a lateral passageway perpendicular to the fluid passageway and with a wedge sealing-slip assembly slideably held at opposite side edges of the wedge to two guide rails of the valve body and moveable from a distant valve open first location within the lateral passageway to a second location between inlet and outlet ports of the valve. The slip-wedge assembly has at least one closure slip with an inside face of the slip slideably engaging a tapering face of the wedge and with the slip at said second location being restrained from further longitudinal movement and moveable in a perpendicular direction of the longitudinal assembly movement into closure engagement with one of the valve ports. The guide rails are diametrically-opposed and extend longitudinally of the inside face of the lateral passageway into the fluid passageway.