The invention relates to a method of venting a synthetically commutated hydraulic pump (2). The connecting fluid conduits (8, 16), connecting said synthetically commutated hydraulic pump (2) with a fluid reservoir (7) is vented at least on start-up of the synthetically commutated hydraulic pump (2), using a fluid intake device (14, 17, 20) that connects to a fixed displacement pump (3).

A coolant pump for an internal combustion engine (ICE) in a vehicle with a central engine control, having a pump shaft that drives an impeller for pumping a coolant. An axial piston pump operated via a wobble plate on a rear face of the impeller, conducts part of the pumped coolant away to a hydraulic circuit that extends from the axial piston pump via a proportional valve back to the pumped coolant and has a branch-off between the axial piston pump and the proportional valve as the hydraulic actuator. A regulating slide valve adjusts coolant volume flow of depending on pressure in the hydraulic circuit. A sensor detects a parameter characteristic of the coolant volume flow and outputs an actual value signal. A dedicated pump control controls the proportional valve based on the actual value signal of the sensor and a desired value signal of the central engine control.

A high and low-pressure integrated air pump includes a single housing including an air inlet and an air outlet. A high-pressure pump is disposed within the housing and in fluid communication with the air inlet, and uses a first outlet passage to discharge to the air outlet. A low-pressure pump is also disposed within the housing and in fluid communication with the air inlet, and uses a second outlet passage to discharge to the air outlet.

A controller for operating a prime mover of a rod pumping unit includes a processor configured to operate the prime mover over a first stroke and a second stroke. The controller is further configured to compute a first motor torque imbalance value for the first stroke and engage adjustment of a counter-balance. The controller is further configured to estimate a second motor torque imbalance value for the second stroke. The controller is further configured to disengage adjustment of the counter-balance during the second stroke upon the second motor torque imbalance value reaching a first imbalance range.

The present invention provides an improved pump assembly incorporating a liquid pump and an air pump and which pump includes a flexible annular diaphragm member coaxially about a piston-forming element forming a component with the liquid pump.

A high and low-pressure integrated air pump includes a single housing including an air inlet and an air outlet. A high-pressure pump is disposed within the housing and in fluid communication with the air inlet, and uses a first outlet passage to discharge to the air outlet. A low-pressure pump is also disposed within the housing and in fluid communication with the air inlet, and uses a second outlet passage to discharge to the air outlet.

A pump and motor assembly (20) includes a centrifugal pump (30), a bent axis hydraulic pump 58, and a wet-type drive motor (228). The motor has a rotor and a stator that are submerged in hydraulic fluid for full lubrication and cooling. A drive shaft 66 is driven by the motor. The centrifugal pump has a rotatable impeller (50) for pumping hydraulic fluid from an inlet (48) to the bent axis hydraulic pump. The centrifugal pump also pumps fluid to the motor for lubrication and cooling. The bent axis hydraulic pump pumps the fluid and discharges the fluid from the system. The centrifugal pump and the bent axis hydraulic pump are rotatable along a common rotational axis R1 that is angled relative to the rotational axis R2 of the drive shaft.

A submersible pumping system has an electric motor, a rotary hydraulic pump driven by the electric motor, and a linear hydraulic pump that is configured to move a production fluid. The rotary hydraulic pump produces a pressurized working fluid that drives the linear hydraulic pump. In another aspect, a method is disclosed for controlling the temperature of an electric motor within a submersible pumping system disposed in a wellbore. The method includes the steps of circulating motor lubricant through a hydraulically driven production pump to reduce the temperature of the motor lubricant.

A connector plate, for mechanically and hydraulically connecting a hydraulic machine with a hydraulic attachment part, includes a plurality of hydrostatic connector recesses. Each recess has a first side that includes a first orifice opening to the hydraulic attachment part, and a second side with a second orifice opening to the hydraulic machine. The plurality of orifices are arranged so as to open in a substantially axially parallel manner with respect to a drive shaft of the hydraulic machine. A hydraulic machine includes such a connector plate, and a hydrostatic unit includes such a hydraulic machine and a hydraulic attachment part.

A connection assembly for use in an axial piston machine has a feed pump and a main body. The main body is equipped with at least one fluid connection. The feed pump is configured as an internal gear pump or as a vane-type pump. A pump assembly defines a planar sealing surface which bears at least indirectly against the main body. The main body has a second recess in which the pump assembly is received at least in certain portions. A separate cover is provided which covers the second recess and the pump assembly in each case at least in certain portions. The cover bears against the main body. An elastic element is installed under preload between the cover and the receiving part such that a corresponding preload force is supported at least indirectly on the main body via the sealing surface.