A lock valve including a poppet valve element which is disposed within a spring chamber, a spring which biases the poppet valve element leftward, and a valve seat which comes into contact with the poppet valve element is disposed in a cavity formed in a valve body to mount a relief valve therein and is positioned further inward than the sleeve of the relief valve. The outer peripheral portion of the poppet valve element has hole portions formed therein at regular intervals. The outer peripheral portion of the valve seat, too, has hole portions formed therein at regular intervals. The valve portion of a solenoid valve is disposed between a passage which is in communication with the spring chamber and a passage which is in communication with a second flow passage open to a low-pressure region such as a hydraulic tank.

An example valve includes: a main piston comprising: a channel that is fluidly coupled to a first port of the valve, a pilot seat, and one or more cross-holes fluidly coupled to a second port of the valve; a pilot check member configured to be subjected to a fluid force of fluid in the channel of the main piston acting on the pilot check member in a proximal direction; a solenoid actuator sleeve comprising a chamber; a first setting spring disposed in the chamber and configured to bias the solenoid actuator sleeve in a distal direction; and a second setting spring configured to bias the pilot check member in the distal direction, such that the first setting spring and the second setting spring cooperate to apply a biasing force in the distal direction on the pilot check member toward the pilot seat against the fluid force.

A hydraulic lock for a hydraulic system includes a flow control valve and a second check valve. The flow control valve having a first inlet, a first outlet, a first check valve and a flow restrictor, each of the first check valve and the flow restrictor being communicably coupled to the first inlet and the first outlet and being arranged in parallel between the first inlet and the first outlet. The second check valve having a second inlet and a second outlet, the second inlet being communicably coupled to the first outlet, the second check valve further having a ball seating surface having an aperture there through, a ball, and a resilient member biasing the ball towards the ball seating surface to seal the aperture, the aperture being communicably coupled to the second inlet and the second outlet.

A lock valve including a poppet valve element which is disposed within a spring chamber, a spring which biases the poppet valve element leftward, and a valve seat which comes into contact with the poppet valve element is disposed in a cavity formed in a valve body to mount a relief valve therein and is positioned further inward than the sleeve of the relief valve. The outer peripheral portion of the poppet valve element has hole portions formed therein at regular intervals. The outer peripheral portion of the valve seat, too, has hole portions formed therein at regular intervals. The valve portion of a solenoid valve is disposed between a passage which is in communication with the spring chamber and a passage which is in communication with a second flow passage open to a low-pressure region such as a hydraulic tank.

A hydraulic park system includes a spool valve linked to a park mechanism. In some circumstances, a hold-out-of-park mechanism is utilized to hold the spool in position. To avoid wear on the aluminum spool, a steel saddle is inserted onto the spool between two lands such that the hold-out-of-park mechanism engages the steel saddle. The steel saddle is inserted from the side of the spool. To ensure that the hold-out-of-park engages the correct side of the saddle, the saddle must be held in a predefined circumferential position about the bore axis. The saddle is constrained from rotation about the spool axis by abutting flat surfaces on the spool and the saddle. The spool is constrained from rotation relative to the bore by the park mechanism.

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.

An apparatus includes a hydraulic circuit that is configured to selectively open fluid communication between one portion of the hydraulic circuit and another portion of the hydraulic circuit, such as a reservoir, based on the flow of the hydraulic fluid in the one portion. When the flow of hydraulic fluid exceeds a selected threshold in the one portion of the hydraulic circuit, the flow of fluid urges the opening of a hydraulic component of the hydraulic circuit to allow fluid communication between the one portion and the reservoir to discharge fluid from the one portion.

A hydraulic lock for a hydraulic system includes a flow control valve and a second check valve. The flow control valve having a first inlet, a first outlet, a first check valve and a flow restrictor, each of the first check valve and the flow restrictor being communicably coupled to the first inlet and the first outlet and being arranged in parallel between the first inlet and the first outlet. The second check valve having a second inlet and a second outlet, the second inlet being communicably coupled to the first outlet, the second check valve further having a ball seating surface having an aperture there through, a ball, and a resilient member biasing the ball towards the ball seating surface to seal the aperture, the aperture being communicably coupled to the second inlet and the second outlet.

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.

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.