A prime mover and a plurality of hydraulic actuators, a hydraulic machine having a rotatable shaft in driven engagement with the prime mover and comprising a plurality of working chambers, a hydraulic circuit extending between a group of one or more working chambers of the hydraulic machine and one or more of the hydraulic actuators, each working chamber of the hydraulic machine comprising a low-pressure valve which regulates the flow of hydraulic fluid between the working chamber and a low-pressure manifold and a high-pressure valve which regulates the flow of hydraulic fluid between the working chamber and a high-pressure manifold. The hydraulic machine being configured to actively control at least the low-pressure valves of the group of one or more working chambers to select the net displacement of hydraulic fluid by each working chamber on each cycle of working chamber volume, and thereby the net displacement of hydraulic fluid by the group of one or more working chambers, responsive to a demand signal, wherein the apparatus further comprises a controller configured to calculate the demand signal in response to a measured property of the hydraulic circuit or one or more actuators.

A high-pressure pump has a metering valve and a valve stopper. The stopper has a regulation portion which an end surface of the valve is brought into contact with. An outer diameter of the regulation portion is equal to an outer diameter of the outer peripheral surface of the valve. A cylindrical sleeve is disposed around the regulation portion. When the end surface of the valve is in contact with the regulation portion, the sleeve covers a tapered surface of the valve.

Idling a hydraulic machine includes electronically controlled high and low-pressure valves, a control system arranged to control opening and closing of said valves, a first idle safety valve arrangement arranged between the first working chamber and a fluid sink with a pressure equal to or lower than the high pressure, operating the hydraulic machine in an empty cylinder idle mode, wherein the high and low-pressure valves are concurrently closed for at least a whole cycle of the varying volume, and releasing hydraulic fluid to the fluid sink only when fluid pressure in the working chamber increases above a set threshold and the empty cylinder mode is enabled, enabling the first idle safety valve arrangement when the hydraulic machine operates in the empty cylinder idle mode, and disabling when not.

The invention relates to a system that intensifies hydraulic pressure, which comprises a main actuation subsystem and a direction-change sub-system. The main actuation subsystem comprises: a motor; a pump; a first piston with a plunger that moves linearly; a travel-limit sensor and a two-way valve at each end of the piston; a pressure control valve connected to the two-way valves; a second piston similar in always to the first and connected to the pressure control valve; a hydraulic motor connected to the two-way valves of the second piston to generate work; and a fluid-cooling means. The direction-change subsystem comprises a secondary motor, a second pump, a pressure accumulator and a pair of solenoid valves for the parallel and independent operation of the two-way valves of the main actuation subsystem.

Various embodiments include methods for operating a high-pressure pump comprising: driving a piston arranged in a compression chamber with a motor shaft; during movement of the piston toward the top dead center, closing the inlet valve so the fluid is then delivered by the piston through an outlet valve; applying a coil current to an electromagnet used to close the inlet valve during and/or after overshooting the top dead center; detecting a start time at which the coil current, on account of starting of an opening movement of the inlet valve, fulfills a predetermined change criterion; labelling a dead center rotation position of the motor shaft at which the piston is at the top dead center based at least in part on the ascertained start time; and adjusting operation of the pump based on the identified dead center rotation position.

A proportional spool valve (1) for adjusting a displaced volume of a displacement pump, in particular of an oil pump in a motor vehicle, the proportional spool valve (1) includes a valve housing (2) and a valve spool (3) which is mounted in the valve housing (2) and displaceable along a displacement axis (V) and which can be displaced against the spring force of a valve spring (6) axially supported on a spring holder (7) which is fixed relative to the valve housing (2) by energizing an electrical coil assembly (10), characterized in that wherein both the preferably single-piece spring holder (7) and the valve housing (2) are made of plastic and that the spring holder (7) is welded to the valve housing (2), an integral welded connection (9) being formed.

An oil change machine or apparatus for removing used oil from an engine has flow lines for removing oil directly from the engine, which can be an automobile engine or a boat engine. The oil change machine can be configured to empty used oil to a designated waste oil bin. The oil change apparatus or machine can be located at a shop, can be portable and maneuverable from locations to locations, or be mounted on a service vehicle for on-site use, such as to perform oil change away from an oil lube center. The oil change machine can have adaptors for use with various engine models and can include an onboard offloading tank, in addition to a service holding tank, for performing multiple oil changes.

A pump device for a cooling circuit of an internal combustion engine of a commercial or motor vehicle includes two electric pumps in parallel, each of which includes a switchable backflow valve in a suction line, so that the electric pumps can be operated selectively individually or in parallel.

A suction damping device for a variable displacement compressor includes a rotor rotatably received within a stator disposed in a suction port of the variable displacement compressor. The rotor includes an aperture and the stator includes a pair of opposing openings in selective fluid communication with the aperture of the rotor. An electromagnetic device controls a rotational position of the rotor relative to the stator based on a condition of an electrically controlled valve used to control an angle of inclination of a swashplate of the variable displacement compressor. A changing of the rotational position of the rotor relative to the stator causes a variable overlap to be formed between the aperture of the rotor and the openings of the stator to control a flow of a refrigerant through the suction damping device.

A high-pressure pump has a metering valve and a valve stopper. The stopper has a regulation portion which an end surface of the valve is brought into contact with. An outer diameter of the regulation portion is equal to an outer diameter of the outer peripheral surface of the valve. A cylindrical sleeve is disposed around the regulation portion. When the end surface of the valve is in contact with the regulation portion, the sleeve covers a tapered surface of the valve.