A first case accommodating a first check valve of a switching valve switching a flow of hydraulic fluid to one of a first chamber and a second chamber of a cylinder device, an inside of which is segmented into the first chamber and the second chamber by a piston, and a second case which is stacked on the first case and in which a first actuation valve of the switching valve is accommodated to be displaced in a direction of stacking the first case are provided. A first valve chamber, accommodating the first actuation valve, of the second case has a pressure receiving surface on which pressure of hydraulic fluid that acts on the first valve chamber acts toward the first case.

A scroll compressor includes a movable scroll, a fixed scroll having a suction passage, a suction pipe, and a suction check valve to open and close an open end of the suction pipe. The suction check valve includes a valve body, a valve seat, and a compression spring to bias the valve body toward the open end of the suction pipe. The valve body includes a first bottom portion, and a first circumferential wall extending toward the valve seat along a peripheral portion of the first bottom portion. The valve seat includes a second bottom portion, and a second circumferential wall extending toward the valve body along a peripheral portion of the second bottom portion. One of the first and second circumferential walls has an outside diameter smaller than an inside diameter of an open end of the other one of the first and second circumferential walls.

Methods and apparatus pertaining to positive displacement pumps, and further to hydraulic actuation systems. In some embodiments the pumps are gear pumps with bi-directional operation. In some embodiments the actuation system includes a motor-driven, reversible operation gear pump providing fluid under pressure to a rod and cylinder.

A pump assembly for a marine cooling system, includes a self-priming pump, a check valve and a housing containing the self-priming pump and the check valve.

The invention relates to a pump, having a contour ring, having a rotor, having vanes, having side plates, having a housing and a housing cover, having under-vane grooves for supplying the lower vane faces with pressure, the vanes being arranged radially displaceably in the rotor and extending under the vanes as a result of the pressure and being pressed against the contour ring. Furthermore, the invention relates to a system for supplying oil to a consumer.

A vane oil pump includes a rotor including a plurality of slits, a housing having an inner circumferential cam surface such that a first pump unit and a second pump unit taking in and discharging oil in accordance with rotation of the rotor are separately disposed in a rotational direction of the rotor, a plurality of vanes respectively fitted in the slits of the rotor, and a pressure adjusting device configured to adjust a second discharge pressure of the second pump unit to a lower pressure than a first discharge pressure of the first pump unit. A back pressure groove is disposed on the housing and is provided to supply back pressure oil to a bottom portion of each slit.

The present invention corresponds to a check valve with an inertial mass that is installed in the bottom of the production tubing and above the progressive cavity pump (PCP) of an oil well, which prevents that the hydrostatic column that is inside of the production tubing go down in the moment where the artificial lift of the column stops for the detention of the PCP pump. If we prevent that this phenomenon to happen, the PCP pump will not rotate in the opposite direction of its normal operation and it will not be clogged by any particulate material that is contained in it.

A scroll compressor includes a movable scroll, a fixed scroll having a suction passage, a suction pipe, and a suction check valve to open and close an open end of the suction pipe. The suction check valve includes a valve body, a valve seat, and a compression spring to bias the valve body toward the open end of the suction pipe. The valve body includes a first bottom portion, and a first circumferential wall extending toward the valve seat along a peripheral portion of the first bottom portion. The valve seat includes a second bottom portion, and a second circumferential wall extending toward the valve body along a peripheral portion of the second bottom portion. One of the first and second circumferential walls has an outside diameter smaller than an inside diameter of an open end of the other one of the first and second circumferential walls.

An electrical oil pump comprising a pump housing containing an electromotively driven pump rotor, and a discharge branch arranged on the housing side and receiving a non-return valve, said valve comprising a preferably spherical closing body arranged such that it can move between a valve seat and a supporting surface, and a closing body holder which is inserted into the discharge branch, forms the supporting surface and comprises through-flow sections, said holder being inserted into the discharge branch for captive holding therein.

A rotary pump for delivering a fluid includes a pump housing having a first and a second fluid connections, wherein the first and the second fluid connections each open into a displacement chamber of the pump housing, a displacement rotor arranged in the displacement chamber, rotatable about an axis of rotation (D) in a first direction of rotation and a second direction of rotation opposite to the first direction of rotation, a plurality of displacement elements for delivering the fluid, distributed over the circumference of the displacement rotor, radially movable with respect to the axis of rotation (D), and designed to deliver the fluid from the first to the second fluid connection when the displacement rotor is rotated in the first direction of rotation, and to deliver the fluid from the second fluid connection to the first fluid connection when the displacement rotor is rotated in the second direction of rotation.