A hydraulic apparatus including an electronically commutated machine having a plurality of working chambers which are controlled on each cycle of working chamber volume to carry out active or inactive cycles of working chamber volume allows only a plurality of defined fractions of cycles to be active cycles to avoid generating frequencies of active cycles which cause low frequency resonances. The demand signal may be quantised into fractions m/n where n is an integer below a threshold selected to avoid repeating patterns of active cycles of more than a cut-off length.

A fire suppression system includes a motor and a foam pump. The foam pump is driven by the motor to inject one or more chemical additives from an off-board additive container into a discharge conduit. A bypass valve is in fluid communication with the output of the foam pump. One or more sensors are configured to measure at least one operating condition of the foam pump. A controller is in communication with the one or more sensors and is operatively connected to the bypass valve. The controller is configured to determine, based on data received from the one or more sensors regarding the at least one operating condition of the foam pump, whether the foam pump is experiencing a loss of prime, and to open the bypass valve in response. The motor may also selectively operate in one of two modes depending on the rotational speed and torque required.

A fire suppression system includes a motor and a foam pump. The foam pump is driven by the motor to inject one or more chemical additives from an off-board additive container into a discharge conduit. A bypass valve is in fluid communication with the output of the foam pump. One or more sensors are configured to measure at least one operating condition of the foam pump. A controller is in communication with the one or more sensors and is operatively connected to the bypass valve. The controller is configured to determine, based on data received from the one or more sensors regarding the at least one operating condition of the foam pump, whether the foam pump is experiencing a loss of prime, and to open the bypass valve in response. The motor may also selectively operate in one of two modes depending on the rotational speed and torque required.

A pump system (120) has a central pump unit (110), with which at least one hook-up unit (130). The least one hook-up unit (130) is from a group of a plurality of hook-up units (130) that can be combined in modular form for setting an operating point of a pump (10) that forms the pump unit (110). A method uses such a hook-up unit (130) in a pump system (120) for setting an operating point of the pump unit (110) thereof. A medical device is provided with such a pump unit (110) or with such a pump unit (110) and at least one hook-up unit (130) combined with the pump unit (110).

A pump system (120) has a central pump unit (110), with which at least one hook-up unit (130). The least one hook-up unit (130) is from a group of a plurality of hook-up units (130) that can be combined in modular form for setting an operating point of a pump (10) that forms the pump unit (110). A method uses such a hook-up unit (130) in a pump system (120) for setting an operating point of the pump unit (110) thereof. A medical device is provided with such a pump unit (110) or with such a pump unit (110) and at least one hook-up unit (130) combined with the pump unit (110).

A system comprises a variable displacement pump, a metering valve, a bypass line, a pressure regulating valve, a position sensor, and a control system. At least one fuel nozzle can be in fluid communication with the output line downstream of the metering valve, wherein the variable displacement pump is configured to supply fuel to the at least one fuel nozzle. The metering valve can be disposed in the output line for controlling outlet flow from the variable displacement pump. The system can also include an actuator line parallel to the variable displacement pump and connected to the output line to provide actuation pressure from pump output of the variable displacement pump.

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.

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.

An oil pump assembly is provided for a vehicle lubrication system including a pumping device, the oil pump assembly presenting an outlet leading from the pumping device, and an inlet leading to the pumping device, the oil pump assembly further including a relief valve presenting a valve chamber arranged to communicate via an outlet relief passage with the outlet, and to communicate via a relief deposit passage with a relief deposit location, the relief valve further including a plunger located in the valve chamber, the plunger being movable between a closed position, in which communication between the outlet relief passage and the relief deposit passage is prevented, and an open position, in which communication between the outlet relief passage and the relief deposit passage is provided, the oil pump assembly further including a control valve for controlling the relief valve, and a control passage adapted to provide a communication between the outlet and the control valve via the valve chamber.

In one featured embodiment, a closure sleeve for a valve comprises a sleeve body surrounding a center axis and defined by an overall length extending from an upstream end to a downstream end. The sleeve body has an internal cavity that is enclosed at the downstream end and is open at the upstream end. The internal cavity is defined in part by a piston contact surface that is defined by an inner diameter. The piston contact surface is configured to slide against a piston to be received within the internal cavity, and a ratio of the inner diameter to the overall length is between 1.0 and 1.5.