The present invention is a hydraulically operated splitting device with a piston cylinder unit comprising an extending chamber and a retracting chamber in which a piston is supported, displaceable in an extending direction and a retracting direction, allowing the extending chamber and the retracting chamber to be impinged with pressurized hydraulic medium for moving the piston at a displacement speed, a cylinder housing at which a plurality of pressure pads is supported, displaceable perpendicular to the extending direction and the retracting direction, a wedged lance connected to a piston rod of the piston and mobile with said piston, which engages wedge-shaped pressure areas of the pressure pads complementary to the wedged lance, and moves the pressure pads perpendicular to the extending direction and the retracting direction, a lubrication unit by which lubricant can be inserted from a lubricant reservoir to an area between the wedged lance and the pressure pads, with the splitting device comprising a protective unit by which the displacement speed can be reduced depending on the fill level of the lubricant in the lubricant reservoir.

A hydraulic circuit for a construction machine is disclosed, which can prevent a loss of pressure during a combined work. The hydraulic circuit includes a variable displacement hydraulic pump, at least two hydraulic actuators driven by hydraulic fluid that is supplied from the hydraulic pump, control valves installed in a center bypass path of the hydraulic pump and shifted to control a start, a stop, and a direction change of the hydraulic actuators, parallel flow paths having inlets branched and connected to predetermined positions on an uppermost stream side of the center bypass path and outlets connected to inlet ports of the control valves, bleed-off paths formed on the control valves other than the lowermost downstream side control valve among the control valves to selectively communicate with the center bypass path, the bleed-off paths communicating with the center bypass path when the plurality of control valves are shifted for a combined work, and a switching valve installed on a lowermost downstream side of the center bypass path to intercept the center bypass path when pilot signal pressure is applied.

A fluid system includes a variable-speed and/or a variable-torque pump to pump a fluid, at least one proportional control valve assembly, an actuator that is operated by the fluid to control a load, and a controller that establishes a speed and/or torque of the pump and a position of the at least one proportional control valve assembly. The pump includes at least one fluid driver that provides fluid to the actuator, which can be, e.g., a fluid-actuated cylinder, a fluid-driven motor or another type of fluid-driven actuator that controls a load. Each fluid driver includes a prime mover and a fluid displacement assembly. The fluid displacement assembly can be driven by the prime mover such that fluid is transferred from the inlet port to the outlet port of the pump.

Modular directional valve with two or more crossing elements (E1 . . . En) able, acting only on the entry side, to manage a variable displacement pump (PA) of the load sensing type.

In particular, this management allows in a single drive, unlike the conventional crossing distributors, to make the flow rate to the utility independent of the load and allows setting a maximum flow rate at the end of the stroke; in multiple drives, it ensures that the sum of the required flow rates is independent of the loads.

A compensated flow rate regulator is placed in the entry side so as to act only on the bypass line LC upstream of the first element (E1 . . . En) while a proportional choke is placed on the load line consisting of a 2-way 2-position tray.

A valve block arrangement configured as a closed center system includes at least one main spool for controlling a hydraulic consumer. The main spool is configured to open and close at least one pressure medium connection between a hydraulic pump and the consumer in controlled, continuous fashion and, in at least one embodiment, is electrically activated. A bypass flow path with a cut valve branches off between the adjustable, hydraulic pump and the main spool. The cut valve is configured to open and close a pressure medium connection between the hydraulic pump and a tank in controlled, continuous fashion. The cut valve is electrically activatable.

A fluid power control system for load handling mobile equipment includes a pair of hydraulic actuators for moving respective cooperating load-engaging members selectively toward or away from each other, or in a common direction, at respective asynchronous speeds to selectively attain either synchronous or asynchronous respective positions of the actuators. The actuators have sensors enabling a controller to monitor their respective movements and correct unintended differences in the actuators' respective movements, such as unintended differences in relative intended positions, speeds, or rates of change of speeds. Respective hydraulic valves responsive to the controller separately and nonsimultaneously decrease respective flows through the respective actuators to more accurately and rapidly correct differences from the intended relative movements of the actuators.

A pneumatic device having a pneumatic cylinder and a piston movably mounted in the pneumatic cylinder to divide an interior of the pneumatic cylinder into two chambers. The chambers are connected to a line network having a valve assembly. The line network, in a plurality of operating states of the valve assembly serving for venting the respective chamber, connects the respective chamber to at least a respective selected one of a plurality of outflow openings, of the pneumatic device, and in a further operating state of the valve assembly, disconnects the respective chamber from the outflow opening. A control installation of the pneumatic device adjusts the operating state of the valve assembly. The line network is designed so that, in at least three of the operating states for venting the respective chamber, the connection between the respective chamber and the outflow opening is established by mutually dissimilar flow resistances.

A hydraulic system includes a hydraulic gear pump with a first gear having a plurality of first gear teeth and a second gear having a plurality of second gear teeth. The hydraulic system also includes a control valve and a control circuit. The control circuit controls the pump to adjust at least one of a flow in the hydraulic system to a flow set point or a pressure in the hydraulic system to a pressure set point, and concurrently establishes an opening of the control valve to adjust at least one of the flow to the flow set point or the pressure to the pressure set point. The control circuit establishes a position of a first tooth relative to a position of a second tooth to seal a fluid path from the outlet of the hydraulic gear pump to the inlet of the hydraulic gear pump.

A hydraulic unit includes an oil tank, a hydraulic pump, a first return pipe, and a first heat exchanger. The oil tank stores a hydraulic oil. The hydraulic pump supplies the hydraulic oil in the oil tank to an actuator. The first return pipe returns the hydraulic oil from a flow path between a discharge port of the hydraulic pump and the actuator to the oil tank. The first heat exchanger causes a coolant to exchange heat with the hydraulic oil returning to the oil tank through the first return pipe.

A valve operating device includes a mounting for attachment to a vehicle and an elongate arm, the free end of which is only moveable across the underlying ground. The joints of the arm pivot around vertical axes and the arm is locked into a desired orientation by a brake at each joint. A valve turning machine is at the free end of the arm. The brakes are engaged and released by a control on the valve turning machine.