The present disclosure relates to a hydraulic control circuit for crane slewing gear having directional valves arranged in work lines and controllable separately for the inflow and outflow to the hydraulic motor for the carrying out of a rotational movement of the slewing gear, wherein an inflow valve serves the control of the oil inflow from a hydraulic pump via the work line to the hydraulic motor and an outflow valve is provided via which the hydraulic motor can be relieved to the tank, wherein the work lines are each connected via at least one check valve to a common inlet of the outflow valve to relieve the hydraulic motor independently of the direction of rotation of the slewing gear via an outflow valve into the tank.

A control valve for a pump for delivering a fluid. The control valve includes: a valve housing which delineates a piston chamber; a piston which can be moved within the piston chamber; and a fluid channel which ports into the piston chamber via a port opening, wherein the port opening defines a port control edge. The valve housing includes a recess which extends into the fluid channel, wherein the recess defines a recess control edge which is axially offset with respect to the port control edge, and/or the piston includes a piston recess which defines a piston recess control edge.

A steering device includes: a cylinder demarcated into first and second chambers by a piston; a main valve having first and second shuttle chambers; a hydraulic source having first and second discharge ports; a first oil passage configured to connect the first chamber and the first shuttle chamber; a second oil passage configured to connect the second chamber and the second shuttle chamber; a third oil passage configured to connect the first shuttle chamber and the first discharge port; a fourth oil passage configured to connect the second shuttle chamber and the second discharge port; and a tank connected to the main valve via the third oil passage and the fourth oil passage. One of the first shuttle chamber and the second shuttle chamber of the main valve is in an opened state when the hydraulic source is stopped.

A compressed-air treatment system and operating method are disclosed. The compressed-air treatment system has a first valve unit configured to charge a control line for a compressor with pressure and a pressure regulator valve unit configured to release pressure from a feed line, A control port of the pressure regulator valve unit is connectable to a second valve unit. A regeneration line which has a check valve for regeneration and which is utilized for a regeneration of a dryer cartridge is connected directly to the control line. During a filling operation the compressed-air treatment system is configured to release leakage air of the regeneration check valve via the first valve unit to surroundings. The filling operation is an operating state in which the compressor is activated to perform a supply of compressed air to a vehicle compressed-air system.

Saturation of a secondary system pressure circuit (18) of a hydraulic system (4) of a motor vehicle transmission is earlier, in that an excess amount of oil from a primary system pressure circuit (16) of the hydraulic system (4) is not directed to a suction charging (40), but rather into the secondary system pressure circuit (18). This can take place via a system pressure valve (9) for the primary system pressure circuit (16), which is configured for this function.

A poppet of a check valve includes a base, a shaft extending from the base, and a sealing head coupled to the shaft and extended away from the base by the shaft. A flow channel is defined between the base, the shaft, and the sealing head. The base includes a plurality of holes.

A pilot pressure supply solenoid valve (36) is disposed in a flow path connecting an inlet port (16) and a pilot chamber (48), and a pilot pressure discharge solenoid valve (38) is disposed in a flow path through which a pressure fluid in the pilot chamber is discharged to the exterior. A flow path, through which the pressure fluid that has passed through a supply valve (26) is discharged to the exterior, is not provided.

A combined valve for insertion into an elongated bore of a power unit body of a hydraulic power unit may have an elongated carrier for receiving a relief and a check valve. The valve may also have a register arranged at a first axial position of a longitudinal axis of the carrier for calibration of the relief valve. The valve may also have a check valve coupled to the carrier at a second axial position along the longitudinal axis of the carrier. The valve may also have a relief valve coupled to the carrier at a third axial position along the longitudinal axis of the carrier. A minimal distance between the first and the second axial position may be less than a minimal distance between the first and the third axial position.

A system for damping mass-induced vibrations in a machine having a long boom or elongate member, the movement of which causes mass-induced vibration in such boom or elongate member. The system comprises multiple pressure sensors operable to measure pressure fluctuations in the hydraulic fluid pressures in the non-load holding and load holding chambers of a hydraulic actuator connected to the boom or elongate member that result from mass-induced vibration, and a processing unit operable to control a first control valve spool in a pressure control mode and a second control valve spool in a flow control mode in order to adjust hydraulic fluid flow to the actuator's load holding chamber to dampen the mass-induced vibration. The system further comprises a control manifold fluidically interposed between the actuator and control valve spools that causes the first and second control valve spools to operate, respectively, in pressure and flow control modes.

A tillage implement has a frame with a center section and first and second outer wing sections hingedly attached the center section such that the wing sections can be operably raised and lowered between a field-working position and a transport position. The sections each carry tillage tools for working the soil. Controlling a precharge in a secondary side of a hydraulic circuit enables the operator of the implement to adjust the downward pressure precharge provided by a plurality of hydraulic cylinders based on a desired stiffness of the implement. A pressure-reducing valve is configured such that flow from the hydraulic supply applies downward pressure precharge on the plurality of tillage tools. Once this desired precharge has been achieved, flow from the hydraulic supply is shut off and a check valve holds the pressure such that the plurality of hydraulic cylinders holds the tillage tools in position.