Disclosed is a railway braking system including a control device having a valve with a body having a cavity and a slide having an internal chamber, supply notches and drainage notches each having an overall passage cross-section for a pressure medium having a shape exhibiting an apex, and being movably mounted in the cavity, between a supply position where the supply notch is opposite a supply groove of the body, and a drainage position where the drainage notch is opposite a drainage groove of the body; the device being configured to allow a substantially stable control configuration, wherein the pressure value of the medium is limited, and wherein the slide is positioned in the cavity such that a control notch of the slide is opposite a control groove of the body while the supply and drainage notches are respectively at a distance from the supply and drainage grooves.

A tillage implement has a frame with a center section and first and second outer wing sections hingedly attached to respective outer ends of the center section. Controlling a pressure in a secondary side of a hydraulic circuit enables adjustment of the downward pressure precharge provided by hydraulic cylinders based on a desired stiffness of the implement. Flow from a hydraulic supply through a pressure-reducing valve puts the downward pressure precharge on gauge wheels. Once this desired downward pressure precharge has been achieved, flow from the hydraulic supply is shut off and a check valve holds the pressure such that the hydraulic cylinders hold the gauge wheels in the desired position.

An electric-powered fail-safe actuator for use with a valve, where the actuator stores potential energy for conversion to kinetic energy to close or open the valve to the fail-safe position.

The disclosure relates to a hydraulic driving system and a driving method for barring. The driving system comprises: three or more main drive hydraulic cylinders, which are divided into two groups to provide pulling and pushing forces to a driven impeller, each main drive hydraulic cylinder including a cylinder body and a piston rod which divides the cylinder body into a rod cavity and a godless cavity, wherein an oil line for the rod cavity and an oil line for the godless cavity of each main drive hydraulic cylinder are controlled by one control valve module; and a control device, which controls the control valve module according to wind and/or load signals, to simultaneously convert flow directions of hydraulic oil in the oil line for the rod cavity and the oil line for the godless cavity of at least one of the three or more main drive hydraulic cylinders.

An electro-hydraulic control apparatus for construction machinery includes a control valve installed in a hydraulic line between a hydraulic pump and an actuator to control operations of the actuator according to a displacement amount of a spool therein, a spool displacement adjusting valve configured to output a secondary pressure in proportion to an inputted pressure command signal to the spool of the control valve to control the displacement amount of the spool of the control valve, a pressure sensor to detect the secondary pressure outputted from the spool displacement adjusting valve, and a controller configured to output the pressure command signal to the spool displacement adjusting valve according to a manipulation signal of the construction machinery, and to correct the pressure command signal when a pressure difference between the detected secondary pressure and a design pressure predetermined by the pressure command signal is out of a preset allowable range.

A pressure control device includes a body having a groove-shaped flow path including a groove part and a widened part, and a filter unit capturing foreign matters mixed in a fluid which passes through the groove-shaped flow path; the filter unit having a frame body including a through hole part and a filter member in a planar plate shape disposed with respect to the through hole part, and the filter unit being accommodated in the widened part. The frame body has: a first part having a first shape, a second part having a second shape smaller than the first shape, and a step part located at a boundary part between the first part and the second part The second part has a storage part provided in a penetrating manner on a bottom part side of the groove-shaped flow path and storing the captured foreign matters.

A hydraulic system of a vehicle includes a hydraulic pump with variable delivery capacity. The hydraulic pump is controllable as a function of a load and operatively connected to a drive of the vehicle. The system includes a first brake system for reducing a speed of the vehicle by at least one friction brake, and a permanent brake system being independent of the first brake system and configured to reduce the speed of the vehicle. The permanent brake system includes a first retarder circuit which cooperates with the hydraulic pump such that kinetic energy is removed from the vehicle by the permanent brake system via the hydraulic pump in order to decelerate the vehicle.

A hydraulic control system for blowout preventers systems, frack valves and chokes, and related wellhead and control equipment used in oil and gas well drilling operations. The hydraulic control system can include one or more hydraulic control valves or pressure regulators including an internal, linear slider and pairs of seal rings. Lapped and polished surfaces of the seal rings and sliders can form a dynamic metal-to-metal seal within the hydraulic control valves or pressure regulators.

A valve, in particular a 4/2-way slide valve (60), includes a valve piston (67), which is guided in a longitudinally movable manner in a valve housing (25), for selectively connecting and disconnecting fluid connections in the valve housing (25), such as a pressure supply connection (P), a tank connection (T), and two utility connections (A, B). A magnetic system (49), to which current can be supplied, controls the valve piston (67). When no current is supplied to the magnetic system (49), the control pressure at one of the utility connections (A, B) can be set, in particular limited, by a control device (62, 70, 79, 80, 88) arranged in the valve housing.

A hydraulic control unit (4) includes a valve bush (12), a valve cover (15) partially closing the valve bush (12) on an end face (S1), a valve slide (13) guided in a longitudinal direction (L) within the valve bush (12), and a housing part (6). The housing part (6) includes a recess (8) matching an external contour of the valve bush (12). An intermediate plate (7) is configured to partially cover the valve cover (15). A spring (14) is arranged within the valve bush (12) and preloads the valve slide (13) in a starting position. The valve bush (12) is inserted, together with the valve cover (15), the valve slide (13), and the spring (14), into the recess (8) of the housing part (6) and jointly form a hydraulic valve (9). The valve bush (12) forms an inlet (19), and the valve cover (15) forms an outlet (31).