An injector generator for use in geomechanical pumped storage systems includes a power end and a fluid end. The fluid end has one or more fluid chambers each having a fluid inlet and outlet that are controlled by rotary valves. The fluid end can function as a pump or as a motor driven by fluid pressure from the geomechanical storage formation.

A portable fluid pump comprises a tank, a positive displacement pump comprising a fluid inlet and outlet, and an electric motor that drives the positive displacement pump, wherein the electric motor is a brushless variable speed electric motor operating at 110 volts or less. A conduit diverts fluid pumped by the positive displacement pump back into the tank and an actuated valve assembly controls fluid flow through the conduit and, therefore, a pressure of fluid flow through the fluid outlet. A pair of sensors measure, respectively, a pressure and a flow rate of fluid flow through the fluid outlet. A system controller receives a target fluid pressure and fluid flow rate and adjusts a throttle position of the actuated valve assembly and a speed of the electric motor such that pressure and flow rate readings from the sensors substantially match, respectively, the target fluid pressure and fluid flow rate.

A rotary fluid pressure device, such as a low-speed, high-torque gerotor motor, is provided with a valve drive shaft that is partially inserted into and engaged with a main drive shaft as the main drive shaft engages a rotating output shaft and engages a rotating and orbiting star member of a positive displacement device. The device is also provided with a drive retainer configured to retain the engagement of the main drive shaft and the valve drive shaft.

A pump may generally include a frame including a reservoir. The reservoir stores a hydraulic fluid. The pump may also include a motor assembly supported by the frame and a pump assembly operably driven by the motor assembly. The pump assembly is in fluid communication with the reservoir and configured to dispense the hydraulic fluid out of the frame. The pump assembly includes a first piston and a second piston, wherein the first piston dispenses hydraulic fluid out of the frame between a first pressure and a second pressure greater than the first pressure, and the second piston dispenses hydraulic fluid out of the frame between the first pressure and a third pressure, the third pressure being greater than the second pressure.

A pump apparatus includes a housing, a shaft, a rotor, a plurality of vanes, a pressure relief passage, and a bearing. The housing includes suction ports and discharge ports. The rotor and the vanes transport hydraulic oil to the discharge ports. The hydraulic oil is sucked from the suction ports. The pressure relief passage is defined in a portion of the housing facing an outer peripheral surface of the shaft. The pressure relief passage brings the discharge ports into communication with a low pressure region where the hydraulic oil is low in pressure. When a pressure of the hydraulic oil in the discharge ports is lower than a first predetermined pressure, the bearing keeps the pressure relief passage out of communication with a passage. When the pressure of the hydraulic oil in the discharge ports has increased to reach or exceed the first predetermined pressure, the bearing brings the pressure relief passage into communication with the passage.

A gear pump could be said to include a first gear and a second gear intermeshed with the first gear. An inlet side is configured to have an inlet connection connected thereto. A discharge side is configured to have a first discharge connection connected thereto. At least one shaft is in operable communication with each of the first and second gears. A bearing is configured to support at least one of the shafts via an inner bore and having an outer peripheral surface. A valve bore is formed into bearing between the inner bore and the outer peripheral surface. A second discharge connection is formed into the bearing. A tap provides fluidic communication between the valve bore and a pad defined in the inner bore. A valve is positioned in the valve bore. The valve includes a moving valve member. A spring biases the moving valve member in a direction toward the second discharge connection. A fuel pump system is also disclosed.

A check valve comprises a housing, a fluid passage, a seat, a valve member and a stop. The fluid passage extends through the housing. The seat is disposed in the fluid passage. The valve member is positioned in the passage to engage the seat. The stop extends through the housing to engage the valve member. The stop is accessible from outside the housing to adjust a distance the valve member can travel from the seat. In one embodiment, the stop includes a variable stop feature, such as an offset pin or a cam. In another embodiment, the stop includes a pump control valve. In yet another embodiment, the housing includes markings to indicate a position of the stop. The valve member comprises a ball or a poppet in different embodiments.

The present invention relates to a fixed displacement pump for use for conveying a hydraulic fluid in a closed hydraulic circuit, a closed hydraulic circuit, a construction machine and a method for operating a fixed displacement pump in a closed hydraulic circuit.

The invention relates to a pump unit for feeding fuel, preferably diesel fuel, to an internal combustion engine, comprising at least one cylinder (14), a piston (15) which is displaceably arranged in the cylinder (14), and a pressure valve (30) for selectively controlling the supply of fuel to the internal combustion engine, wherein the pressure valve (30) has a closure part (38, 46, 51) provided with a cavity (44, 49, 53) that opens to the outside on an end surface (43, 48, 52) facing the piston (15) of the closure part (38, 46, 51).

An oil pump includes a rotation shaft, a pump unit including an inner rotor and an outer rotor, and a casing provided with a pump chamber accommodating the pump unit, wherein at least one of a first suction passage, a first ejection passage, a second suction passage, and a second ejection passage of the casing includes a check valve provided in the oil carrying passage and the check valve includes a ball and a seating portion allowing the ball to be seated thereon and does not use a spring.