Abstract: A lock valve assembly is provided in a hydraulic control system for a double acting hydraulic jack which is adapted to permit the desired substantially unrestricted flow of inlet fluid selectively to either end of the jack under all operating conditions and is automatically self-conditioning to either restrict when necessary or not to restrict the flow of outlet fluid from either end of the jack as may be required.

Abstract: A deaeration valve useful in a pressurized fluid system for reducing the transfer of air from a sump to the principal reservoir of the system is disclosed. The valve comprises a body including a bore longitudinally therethrough and a poppet-type spool slidably disposed in the bore. An orifice is axially-disposed in the end of the valve spool which is adapted to fit in the seat end of the bore. Air escapes through the orifice when an inadequate amount of fluid pressure is exerted against the orifice end of the spool to force the spool significantly away from the seat. When the spool is forced significantly away from the seat, fluid flow proceeds through a hole which communicates with the bore adjacent the seat. The spool is biased by a spring or the like against the seat, so that the pressure due to the fluid must build up to a significant value before the spool will be forced away from the seat and the hole will be open to fluid flow.

Abstract: A deaeration valve useful in a pressurized fluid system for reducing the transfer of air from a sump to the principal reservoir of the system is disclosed. The valve comprises a body including a bore longitudinally therethrough and a poppet-type spool slidably disposed in the bore. An orifice is axially-disposed in the end of the valve spool which is adapted to fit in the seat end of the bore. Air escapes through the orifice when an inadequate amount of fluid pressure is exerted against the orifice end of the spool to force the spool significantly away from the seat. When the spool is forced significantly away from the seat, fluid flow proceeds through a hole which communicates with the bore adjacent the seat. The spool is biased by a spring or the like against the seat, so that the pressure due to the fluid must build up to a significant value before the spool will be forced away from the seat and the hole will be open to fluid flow.

Abstract: A Self-Contained Breathing Apparatus with automatic redundant fluid pressure controls and a facemask mounted low pressure warning device. The apparatus utilizes two stages of pressure regulation wherein the final stage is the demand regulator that delivers the breathing gas to the wearer. The first state includes a pair of pressure regulators connected in parallel with different outlet pressures, both of which reduce the pressure of the stored supply gas to pressures compatible with the second stage breathing demand regulator. A primary regulator in the first stage delivers a low output pressure to the second stage demand regulator. In the event of a "failure closed" condition of the primary regulator an automatic transfer valve switches on the backup regulator and communicates its slightly higher outlet pressure to the demand regulator.

Abstract: A fluid control valve, which relates to fluid control valves in which a pilot passage is opened or closed as a pilot flow is detected in the said pilot passage by means of a limit orifice mechanism located at the middle of the flow and a valve spool is switched by the differential pressure produced in the fluid passing the said limit orifice mechanism so as to effect a switch-over between unloaded and loaded states, and incorporates, as the said valve spool, a first valve spool effecting the switching action based on the differential pressure of the fluid passing the limit orifice mechanism and a second valve spool arranged in series with the first valve spool effecting a switching action being effected by the fluid pressure so that a load check function may also be provided.

Abstract: This invention relates to supply circuits for fluids under pressure, particularly gases. Such circuits ordinarily comprise a main pipe between a source of fluid and a point of consumption, and to which main pipe is fitted a regulator and pressure-reducer and at least one obturator is normally fitted to this main pipe downstream of the regulator and pressure-reducer. In such an arrangement, the present invention provides means for minimising over-pressures consequent on the said obturator closing which are caused by the inertia of the regulator, which means is fitted as a by-pass to the main pipe on either side of the regulator and pressure-reducer. In one preferred embodiment, this means comprises a venturi and a reservoir which is connected by a first pipe means to the venturi and wherein the venturi is fitted to a second pipe means as a by-pass to the regulator and pressure-reducer, a valve being provided in the second pipe means upstream of the venturi.