Flow control over a hydraulic pump and flow dividing control of a plurality of directional control valves associated with actuators can stably be exercised even in a case in which differential pressures across the directional control valves are quite low, an abrupt change in a flow rate of the hydraulic fluid supplied to each actuator is prevented and excellent combined operability is realized even in an abrupt change in a demanded flow rate at a time of transition from a combined operation to a sole operation, and realizing excellent combined operability, and a meter-in loss in each directional control valve is reduced to realize high energy efficiency. Demanded flow rates of the directional control valves are calculated from input amounts of operation levers, openings of flow control valves are controlled using the demanded flow rates, a meter-in pressure loss of a predetermined directional control valve is calculated from the demanded flow rates and meter-in opening areas of the directional control valves, and a set pressure of an unloading valve is controlled using a value of the meter-in pressure loss.

An asymmetric linear actuator is provided which integrates a hydraulic dissipater and an electric motor and power screw which generates small forces. The actuator is configured so that an electric motor drives a power screw which drives a rod through a cylinder to provide linear actuation. The cylinder is fluid-filled and incorporates a piston that separates the cylinder into a first and second fluid chamber which are filled with a first and second volume of working fluid. Movement of the piston and rod assembly results in fluid movement between the first and second volumes of working fluid and through the fluidic restriction. The fluidic restriction can be proportionally controllable via an electric motor which enables controllable power dissipation via control of the fluidic restriction motor and controllable power generation via control of the power screw motor.

The present invention relates to a work machine having at least one hydraulic actuator for actuating a piece of working equipment and having a first displacement unit that is driven by a drive assembly of the work machine and that feeds the hydraulic actuator with hydraulic medium from a hydraulic tank, wherein at least one second displacement unit is provided that is driven by the drive assembly and that feeds the hydraulic actuator and/or further hydraulic consumers with hydraulic medium from a hydraulic tank in the working mode and that is drivable during a recovery mode by the hydraulic volume displaced by the at least one hydraulic actuator or by a hydraulic consumer to feed kinetic energy back to the drive assembly.

In one aspect, a system for controlling an operation of an actuator mounted on a seed planting implement may include an actuator configured to adjust a position of a row unit of the seed planting implement relative to a toolbar of the seed planting implement. The system may also include a flow restrictor fluidly coupled to a fluid chamber of the actuator, with the flow restrictor being configured to reduce a rate at which fluid is permitted to exit the fluid chamber in a manner that provides damping to the row unit. Furthermore, the system may include a valve fluidly coupled to the flow restrictor in a parallel relationship such that the valve is configured to permit the fluid exiting the fluid chamber to flow through the flow restrictor and the fluid entering the fluid chamber to bypass the flow restrictor.

A thread compensator for performing casing running operations. An example method may include visually ascertaining operational parameters of a thread compensator displayed on a video output device. The thread compensator may be connected between a top drive and a travelling block, and a casing running tool may be connected to the top drive. The operational parameters may include the height that the top drive is lifted by the thread compensator and force applied to casing by the top drive. The method may further comprise manually controlling well construction equipment to perform casing running operations based on the ascertained operational parameters.

A discharge pressure scale (30) includes a valve housing (41) having a functional connector (A), a return flow connector (T) and a user connector (28). A valve piston (52) is guided such that it moves longitudinally against the effect of an energy accumulator (42), moving from a respective opening or regulating position, against a valve seat (94), into a closed position. The user connector (28) and return flow connectors (T) are separated from one another. The fluid pressure present at the user connector (28) can be guided onto a pressure-active surface (A.sub.1*) of the valve piston (52) by a pressure compensation device (70) in such a way that it moves into its respective opening or regulating position in a pressure-compensated manner due to the force of the energy accumulator (42).

A valve body of a speed controller includes a main body that extends along a first axis and a mounting portion that projects from a side of the main body along a second axis that intersects the first axis orthogonally. A first port, a needle valve, and a check valve are disposed in the main body. The mounting portion, which is a portion to be mounted on a cylinder portion, includes a second port formed therein. A position at which the mounting portion is disposed on the side of the main body is away from the first axis in a direction of a third axis that orthogonally intersects the first axis and the second axis.

A hydraulic drive device for a cargo vehicle includes a hydraulic cylinder supplying and discharging of hydraulic oil, an operation member that operates the hydraulic cylinder, a hydraulic pump, a lowering oil path connecting the hydraulic cylinder and the hydraulic pump, an operation valve disposed in the lowering oil path, a bypass oil path that branches off from the lowering oil path, a bypass flow rate control valve disposed in the bypass oil path and that controls a bypass flow rate, and a resistance element that is disposed closer to the hydraulic cylinder than the operation valve in the lowering oil path and that increases a fluid resistance. A pilot flow path of the bypass flow rate control valve is connected to a part of the lowering oil path between the hydraulic cylinder and the resistance element.

The present invention relates to a hydraulic apparatus, in particular to a hydraulic valve or to a hydraulic regulator, having a housing, at least one piston axially displaceably supported in a housing bore, and a respective at least one compression spring acting on the at least one piston, wherein at least one externally accessible regulating screw is adjustable within the housing bore to set the preload of the compression spring in the axial direction, wherein the adjustment distance of the at least one regulating screw is divided into at least two adjustment ranges and the torque to be applied for the adjustment of the regulating screw is larger in a second adjustment range than in a first adjustment range.

An air cylinder fluid circuit is formed by connecting a switching valve, which switches the supply and discharge of compressed air, and cylinder port parts of an air cylinder by means of pipes, wherein the acoustic velocity conductance of the pipes is smaller than the acoustic velocity conductance of the switching valve and the cylinder port parts.