A hydraulic control assembly includes means for holding pressure in a cylinder to inhibit boom or arm drop of a machine in the event that a hose between the cylinder and a main control valve (MCV) ruptures. The pressure holding means of the hydraulic control assembly include a hydraulic valve and a parts-in-body check assembly both configured for insertion into a valve cavity defined by a valve body. The hydraulic valve comprises a proportional piloted valve that controls pressure.

An example valve assembly includes a meter-in valve configured to be fluidly coupled to a first source of pressurized fluid and control fluid flow from the first source of pressurized fluid into a first chamber of an actuator; a counterbalance valve including configured to open and control fluid flow from a second chamber of the actuator to a tank in response to a pilot pressure fluid signal received at a pilot port of the counterbalance valve; and a pressure reducing valve configured to be fluidly coupled to a second source of pressurized fluid and to be fluidly coupled to the pilot port of the counterbalance valve, where the pressure reducing valve is configured to receive pressurized fluid from the second source of pressurized fluid and, when actuated, provide the pilot pressure fluid signal to the pilot port of the counterbalance valve.

An example valve assembly includes a meter-in valve configured to be fluidly coupled to a first source of pressurized fluid and control fluid flow from the first source of pressurized fluid into a first chamber of an actuator; a counterbalance valve including configured to open and control fluid flow from a second chamber of the actuator to a tank in response to a pilot pressure fluid signal received at a pilot port of the counterbalance valve; and a pressure reducing valve configured to be fluidly coupled to a second source of pressurized fluid and to be fluidly coupled to the pilot port of the counterbalance valve, where the pressure reducing valve is configured to receive pressurized fluid from the second source of pressurized fluid and, when actuated, provide the pilot pressure fluid signal to the pilot port of the counterbalance valve.

A control valve is provided for construction equipment having a holding valve which prevents the natural lowering of an operation apparatus due to the dead weight of the operation apparatus when an actuator is in a neutral position. The control valve includes a valve body, a spool, a holding valve, a control valve, and a pilot pressure control valve. The control valve can save manufacturing cost as well as allow better use of space for construction equipment.

A valve assembly includes a linearly moving main slider, a pilot valve, a control oil inlet, and a control oil return. The pilot valve is designed as a 4/3 proportional directional valve, via which a first end face and an opposite second end face of the main slider can be fluidly connected selectively to the control oil inlet or the control oil return so that the main slider (20) is hydraulically movable by adjusting the pilot valve. The pilot valve is electrically adjustable depending on a target current. A position sensor is provided, with which an actual position of the main slider can be measured. A positioner is provided, with which the actual position can be regulated by adjusting the target current to a predefinable target position. The pilot valve is connected to the control oil return via a check valve. The check valve only permits fluid flow from the pilot valve toward the control oil return. The check valve is preloaded to a closed position by means of a first spring so that it opens at a predetermined opening pressure. The leakages at the pilot valve from the control oil inlet toward the check valve are designed to be so large that if the pressure at the control oil inlet exceeds the opening pressure by at least 2 bar, the opening pressure of the check valve is present immediately upstream of the check valve.

The present invention relates to a system preventing the pressured oil leakage in a cylinder line enabling very low leakage rates without using the valve or the system, or without reducing the diametrical space between the housing and spool.

System and method for a lock valve for a hydraulic actuator. The lock valve includes a valve housing coupled to the hydraulic actuator. The valve housing defines a chamber in selective fluid communication with a hydraulic circuit. The lock valve includes a valve body received within the chamber and responsive to the hydraulic circuit to move to an unlock position in which the lock valve is unlocked. The valve body includes a rod having a first end and an opposite second end. The valve body includes a head coupled to the rod between the first end and the second end. The head is responsive to the hydraulic circuit to move the valve body to the unlock position, and in the unlock position, the first end of the rod extends outwardly from the valve housing to visually indicate the lock valve is unlocked.

A fluid pressure control device includes a load holding mechanism that is configured to hold the load pressure of the load side pressure chamber. The load holding mechanism includes a switching valve having a communication passage configured to be blocked from the third pressure chamber by the second land section in a case where the spool is closed, and providing communicate between the second supply port and the discharge port in accordance with the movement of the spool in the valve opening direction. In a case where the spool is moved in the valve opening direction, at the same time when or after the second supply port communicates with the discharge port via the communication passage, the first land section is brought into sliding contact with the annular projecting section and the first supply port and the discharge port are blocked from each other.

A hydraulic valve assembly includes a connection section, a first valve section and a pressure line. The first valve section has a first spool piston, a first spool diverter, at least one first consumer port and at least one second consumer port. The first spool diverter can be switched at least into a first spool diverter switching position and a second spool diverter switching position. A shut-off valve is disposed in the pressure line and blocks the pressure line in a blocking position and can be switched from the blocking position into a first release switching position and a second release switching position. The shut-off valve switches into the first release switching position when the first spool diverter is in the first spool diverter switching position and into the second release switching position when the first spool diverter is in the second spool diverter switching position.

A valve, in particular a pilot-operated proportional directional poppet valve, has a valve housing (7) with a fluid inlet (21) and a fluid outlet (23). The fluid stream between the fluid inlet (21) and the fluid outlet (23) is adjustable by a main piston (27). A pilot valve chamber (37) on a rear face (29) of the main piston (27) has a pilot valve closing member (33) movable by an actuating device (69) to adjust the fluid stream between the pilot valve chamber (37) and the fluid outlet (23). A supply aperture (3) is between the fluid inlet (21) and the pilot valve chamber (37). The opening cross-section of the supply aperture (3) can be reduced by a control element (49).