A hydraulic circuit is pressurized by a hydraulic pump driven by a power source in a machine. The hydraulic circuit is configured to use pressurized fluid from an accumulator to drive a hydraulic accessory when the hydraulic pump is inactive and the power source is shut down for fuel savings during idle operations. A valve may be configured to selectively supply pressurized hydraulic fluid to the accessory when the pump is inactive.

A hydraulic system is provided to selectively and independently route pressurized fluid to one or more operational systems of a machine. The hydraulic system is capable of switching fluid flow in operation from one of the operational systems to another of the operational systems in the event of hydraulic drive power being required by the latter one of the operational systems. The hydraulic system is also configured to continue supplying a nominal amount of fluid to support one or more auxiliary functions, for example, a lubrication system for bearings associated with the former one of the operational systems while routing the pressurized fluid to the latter one of the operational systems. A recirculation and anti-cavitation arrangement is also provided to allow recirculation of fluid to a hydraulic motor in the former one of the operational systems when pressurized fluid is being routed to the latter one of the operational systems.

In a hydraulic drive of a tool, a piston is adapted to be acted upon by a pump via a pressure limiting seat valve and a parallel switching seat valve of a valve arrangement. A restriction is provided in a pressure line upstream of the pressure limiting seat valve which is connected to a tank on the flow-off side. A drain line leads from a working chamber of the piston via the switching seat valve to the tank. A closing side is adapted to be acted upon by pressure and an opening side is adapted to be acted upon by a force generated when the pressure limiting seat valve responds. The pump is adapted to be switched off when the maximum operating pressure has been reached, so that the piston will execute a return stroke. A pressure-increasing restriction is provided on the flow-off side of the pressure limiting seat valve.

A linear actuator system includes a linear actuator and an integrated pump assembly connected to the linear actuator to provide fluid to operate the linear actuator. The integrated pump assembly includes a pump with two fluid drivers, each fluid driver comprising a prime mover and a fluid displacement assembly to be driven by the prime mover such that fluid is transferred from a first port of the pump to a second port of the pump. The pump assembly also includes two valve assembles to isolate the pump from the system. The linear actuator system also includes a controller that establishes the pump in a normal mode of operation in which the prime movers are independently driven and switches to a fail-safe mode of operation in which only one prime mover is operated.

There is provided a fluid circuit capable of continuously driving pressure-increasing devices with a simple configuration. A plurality of pressure-increasing devices are connected in parallel to a fluid supply device that delivers a working fluid. A stroke direction of the piston of each of the pressure-increasing device is switched by the working fluid. A phase of the piston of one pressure-increasing device is different from a phase of the piston of the other pressure-increasing device.

An apparatus for operating a load-controlled hydraulic supply of an agricultural tractor includes a hydraulic pump which is adjustable with respect to the displacement volume for supplying pressurized hydraulic fluid, a proportional valve which is electrically actuatable, a primary hydraulic consumer to carry out a superordinate hydraulic function and to be directly connected to a conveying outlet of the hydraulic pump, a secondary hydraulic consumer to carry out a subordinate hydraulic function and to be connected to the conveying outlet of the hydraulic pump via the proportional valve, and a control unit configured to move the proportional valve into a closed valve position when the control unit recognizes that at least one of a required power of the primary and secondary hydraulic consumers exceeds the conveying capacity of the hydraulic pump and the subordinate hydraulic function of the secondary hydraulic consumer is inactive.

A hydraulic system for the pitch angle adjustment of a rotor blade of a wind turbine) includes a variable displacement pump, a hydraulic accumulator, a dynamic valve, a control valve, a tank and a pitch cylinder. The variable displacement pump is connected to the control valve via a first connecting line and the control valve is connected to the tank via a second connecting line and to a piston side of the pitch cylinder via a third connecting line and to a rod side of the pitch cylinder via a fourth connecting line. In a first switching position, the first connecting line is connected to the third connecting line and in a second switching position, the first connecting line is connected to the fourth connecting line and the second connecting line is connected to the third connecting line.

A hydraulic system (12) for an aircraft (10), wherein the hydraulic system (12) includes a hydraulic power pack (14), a hydraulic fluid reservoir (28) and a hydraulic pump (30), a hydraulic consumer (18), a high-pressure supply line (38) supplying the hydraulic consumer (18) with hydraulic fluid under higher pressure, and a low-pressure return line (40) returning hydraulic fluid under lower pressure from the hydraulic consumer (18); heating device (42) with a short-cut line (44) connecting the high-pressure supply line (38) with the low-pressure return line (40) and a heater valve (46) for opening and closing the short-cut line (44), and a control and monitoring unit (43). Temperature management includes automatically controlling a fluid temperature by monitoring the fluid temperature and controlling the heater valve (46).

A hydraulic drive system for operating a hydraulic cylinder in first and second movement profiles. A hydraulic drive unit includes first and second hydraulic machines, each with first and second connections. In the first movement profile, a first cylinder chamber of the hydraulic cylinder is fluidly connected to a first fluid reservoir and a second cylinder chamber is fluidly connected to the second connection of the second hydraulic machine. In the second movement profile, the first connection of the first hydraulic machine is connected to the second connection of the second hydraulic machine.

A linear actuator system includes a linear actuator and an integrated pump assembly connected to the linear actuator to provide fluid to operate the linear actuator. The integrated pump assembly includes a pump with two fluid drivers, each fluid driver comprising a prime mover and a fluid displacement assembly to be driven by the prime mover such that fluid is transferred from a first port of the pump to a second port of the pump. The pump assembly also includes two valve assembles to isolate the pump from the system. The linear actuator system also includes a controller that establishes the pump in a normal mode of operation in which the prime movers are independently driven and switches to a fail-safe mode of operation in which only one prime mover is operated.