A hydraulic tool can include a hydraulic cylinder, a piston within the hydraulic cylinder, and a rotary valve. The piston can be configured to move between a retracted position and an extended position. The piston can include a piston ram and a piston rod that define a ram side and a rod side inside the hydraulic cylinder. The rotary valve can be moved between a first position and a second position. The first position can be configured to direct flow at a first variable speed and a first variable force to the ram side of the hydraulic cylinder and the second position can be configured to direct flow at a second variable speed and a second variable force to the rod side of the hydraulic cylinder.

The technology generally relates to tailoring a back pressure regulator in a chromatographic system to reduce unswept volume within the back pressure regulator to achieve better sample detection and a reduction in chromatographic band distortion effects.

A direction control valve group for a construction machine that controls an amount of pressure oil supplied to a hydraulic actuator from a hydraulic pump that discharges the pressure oil is provided. The direction control valve includes a cylinder port that supplies the pressure oil to the hydraulic actuator, a bridge passage that is switchably connected and disconnected to the cylinder port according to a change in position of a first spool, and an internal passage that supplies the pressure oil discharged from the hydraulic pump to the bridge passage. The first spool is provided in the internal passage.

A compensator device includes a hydraulic cylinder with a first end, a second end and an inner cylinder rod extending axially from the second end; and a piston rod with a piston movable axially within the cylinder. The inner cylinder rod has an end with a blocking diameter. The piston rod is generally hollow and includes a cavity to receive the blocking diameter of the inner cylinder rod.

A drive control method of a hydraulic actuator of a construction machine includes: determining whether a rotation operation lever and a working device operation lever are operated; calculating the required pressure of a hydraulic cylinder fix a working device according to the operation amount of the rotation operation lever; calculating the required flow rates of a swing motor and the hydraulic cylinder for the working device, the required flow rates corresponding to the operation amounts of the working device operation lever and the rotation operation lever; calculating the opening areas of the first and second proportional solenoid valves of an inlet side and an outlet side by using the calculated required pressure and required flow rates of the hydraulic cylinder for the working device and the swing motor; and calculating current values to be inputted into the first and second proportional solenoid valves of the inlet side and the outlet side according to preset data values or a table in comparison with the calculated opening areas of the first and second proportional solenoid valves of the inlet side and the outlet side.

A drive control method of a hydraulic actuator of a construction machine includes: determining whether a rotation operation lever and a working device operation lever are operated; calculating the required pressure of a hydraulic cylinder fix a working device according to the operation amount of the rotation operation lever; calculating the required flow rates of a swing motor and the hydraulic cylinder for the working device, the required flow rates corresponding to the operation amounts of the working device operation lever and the rotation operation lever; calculating the opening areas of the first and second proportional solenoid valves of an inlet side and an outlet side by using the calculated required pressure and required flow rates of the hydraulic cylinder for the working device and the swing motor; and calculating current values to be inputted into the first and second proportional solenoid valves of the inlet side and the outlet side according to preset data values or a table in comparison with the calculated opening areas of the first and second proportional solenoid valves of the inlet side and the outlet side.

Embodiments of the present invention disclose a hydraulic cable tensioning machine, comprising a tension puller for tensioning a cable, a hydraulic motor for controlling the action of the tension puller, and a hydraulic driving system for driving the hydraulic motor to operate, wherein an output end of the hydraulic driving system is connected to an input end of the hydraulic motor, and a power output end of the hydraulic motor is connected to a power input end of the tension puller.

A valve includes a basic body, control spool, sealing ring, and control cover. The control spool is received in the basic body to be movable along a longitudinal axis. The basic body includes a counter-sealing surface, connecting channel, and tank channel having at least one first annular groove surrounding the control spool. The control cover and at least one end face of the control spool facing toward the longitudinal axis delimits, at least in part, a control space. The control cover includes a sealing surface that abuts the counter-sealing surface of the basic body. At least one of the sealing surface and the counter-sealing surface includes a sealing groove that surrounds the control space in ring-like fashion. The sealing ring is received in the sealing groove. The connecting channel opens out into the tank channel and into the sealing groove.

The present disclosure relates to a load-sense system such as a load-sense steering system that operates in a static load-sense mode for low flows and operates in a dynamic load-sense mode for high flows.

Proposed are directional control hydraulic valves and a system including the same, the system including: a first valve controlling a flow of a fluid flowing thereinto from a first input port by being interlocked with a solenoid valve that is switched to an excited (on) state or non-excited (off) state; and a second valve connected to the first valve and controlling a flow of the fluid flowing thereinto from the first valve by a fluid flowing thereinto from a second input port or a third input port, wherein at least a part of the fluid having been passed through the first valve is discharged through a first output port and then flows into the second input port or the third input port. In addition, the system including at least two directional control valves may be provide, whereby multiplexing of the system may be implemented.