A planar micromechanical actuator suspended on opposing suspension zones including a neutral axis between the opposing suspension zones, first to fourth segments into which the planar micromechanical actuator is segmented between the opposing suspension zones, each including a first electrode and a second electrode which form a capacitor and are isolatedly affixed to each other at opposite ends of the respective segment along a direction between the opposing suspension zones so as to form a gap between the first and second electrode along a thickness direction, the gap being offset to the neutral axis along the thickness direction, and wherein the first to fourth segments are configured such that the planar micromechanical actuator deflects into the thickness direction by the first and fourth segment bending into the thickness direction and the second and third segments bending contrary to the thickness direction upon a voltage being applied to the first and second electrodes of the first to fourth segments.

An exemplary pump jack system (10) is operable to cause well liquid to be pumped to the surface by a subsurface well pump (29). The exemplary system includes a driver (42) that is in rotatable connection with a pump/motor (48). The pump/motor is a rotary type variable output positive displacement pump/motor that delivers working liquid at a selectively variable flow rate in closed liquid connection to a motor/pump (38). The exemplary motor/pump includes a rotatable output coupler (40) that is in operative connection with a gearbox (34) which causes the pump jack to undergo reciprocating motion. The motor/pump is a rotary type positive displacement motor/pump that is in closed liquid connection with the pump/motor liquid inlet of the pump motor. The pump/motor is operable to deliver working liquid flow therefrom to drive the motor/pump at a selectively variable speed while the driver operates at a generally constant rotational speed. Return force which acts on the motor/pump during at least a portion of the pump jack cycle is operative to cause the motor/pump to urge working liquid toward the pump/motor which assists the driver in pump/motor operation.

An exemplary pump jack system (10) is operable to cause well liquid to be pumped to the surface by a subsurface well pump (29). The exemplary system includes a driver (42) that is in rotatable connection with a pump/motor (48). The pump/motor is a rotary type variable output positive displacement pump/motor that delivers working liquid at a selectively variable flow rate in closed liquid connection to a motor/pump (38). The exemplary motor/pump includes a rotatable output coupler (40) that is in operative connection with a gearbox (34) which causes the pump jack to undergo reciprocating motion. The motor/pump is a rotary type positive displacement motor/pump that is in closed liquid connection with the pump/motor liquid inlet of the pump motor. The pump/motor is operable to deliver working liquid flow therefrom to drive the motor/pump at a selectively variable speed while the driver operates at a generally constant rotational speed. Return force which acts on the motor/pump during at least a portion of the pump jack cycle is operative to cause the motor/pump to urge working liquid toward the pump/motor which assists the driver in pump/motor operation.

A control arrangement for a variable displacement pump includes a pressure control unit and a separate mechanical control unit, each mounted on a housing of the variable displacement pump. The pressure control unit provides pressure control for the variable displacement pump and the mechanical control unit provides rotary feedback control for the variable displacement pump.

A method of optimizing pump performance includes providing a measurement device on a pump equipment assembly, gathering a data reading from the measurement device during operation of the pump equipment assembly, evaluating the data reading, and determining whether remedial action needs to be taken to improve the performance of the pump equipment assembly based on the evaluation.

A reciprocating compressor-expander according to the present invention comprises a cylinder, a piston, a crankshaft connected to the piston, a first valve for a low pressure compressible fluid, a second valve for a high pressure compressible fluid, and a valve drive mechanism for driving the first valve and the second respectively such that, during a compression process, the low-pressure compressible fluid is sucked into the cylinder from the first valve in synchronization with the rotation of the crankshaft and the high-pressure compressible fluid compressed in the cylinder is discharged from the second valve, and that, during an expansion process, the high-pressure compressive fluid is introduced from the second valve into the cylinder, and the low-pressure compressible fluid expanded in the cylinder is discharged from the first valve.

One object is to provide a hydraulic pump that allows a drive source to be started with a small torque. The hydraulic pump includes: a cylinder block having a plurality of cylinder bores and disposed so as to be rotatable; pistons each retained in associated one of the cylinder bores so as to be movable; a swash plate for controlling the amount of movement of the pistons in accordance with the size of the tilt angle; a first pressing unit for pressing the swash plate in such a direction as to reduce the tilt angle of the swash plate; and a second pressing unit for pressing the swash plate in such a direction as to increase the tilt angle of the swash plate by the pressure supplied from the outside.

A test controller and method to operate a rotary motor of a pump are provided. The test controller includes a test speed circuit electrically coupled to, but detachable from, the pump and being configured to apply at least one signal to the pump motor to cause the pump motor to rotate at a predetermined test speed and/or for a predetermined test time. An actuator selectively activates the test speed circuit to operate the pump motor at the predetermined test speed and/or for the predetermined test time. The method includes electrically coupling the test controller to the pump and, in response to selective activation of the actuator, selectively activating the test speed circuit to apply at least one signal to the pump motor to operate the pump motor at a predetermined test speed and/or for a predetermined test time. The method further includes detaching the test controller from the pump.

A hydraulic feed device may include a pendulum-slide cell pump having an internal rotor drivingly connected to an external rotor via pendulum slides. A hydraulic positioning device may have a positioning element for changing an eccentricity between the internal rotor and the external rotor. The positioning element may be preloaded by a spring device for setting a maximum eccentricity. The positioning device may have a first pressure adjusting and a second pressure adjusting chamber for adjusting the positioning element. The first pressure adjusting chamber may be permanently hydraulically connected to a pressure side of the pendulum-slide cell pump and configured to hydraulically counteract the spring device. The second pressure adjusting chamber may be controlled via a control valve and hydraulically connected to the pressure side of the pendulum-slide cell pump and configured to hydraulically counteract the spring device.

A method including: determining a cooling value; and comparing the cooling value to an activation point of a lead compressor. The lead compressor is in a tandem set of scroll compressors of a cooling system. The tandem set of compressors comprises a lag compressor. The method further includes: activating the lead compressor when the cooling value is greater than the activation point; activating the lag compressor subsequent to activating the lead compressor; and determining whether conditions exist including: an alarm associated with the lag compressor being generated, and the lead compressor being deactivated. The method further includes deactivating the lag compressor when at least one of the conditions exists in the cooling system.