A mast assembly that includes a mast and a hydraulic circuit for moving the mast. The hydraulic circuit includes a primary hydraulic cylinder coupled to the mast to rotate the mast about a pivot axis and a secondary hydraulic cylinder extending from a rod end to a cap end that is fluidly coupled to the primary hydraulic cylinder. A directional valve is fluidly coupled between the primary hydraulic cylinder and secondary hydraulic cylinder to keep a pressure on the cap end of the secondary hydraulic cylinder greater than the pressure on the rod end of the secondary hydraulic cylinder during all operating conditions.

An actuation chamber (2) provided in a housing (1) is communicatively connected to a supply and discharge port (6) via a pressurized oil supply and discharge passage (7). A valve case (11) of a sequence valve (10) is attached to an attachment hole (8) provided at an intermediate portion of the supply and discharge passage (7). A valve seat (25) is provided in a cylindrical hole (20) provided in the valve case (11). A valve member (26) is biased leftward toward the valve seat (25) by a pressure-setting spring (31). When pressure of pressurized oil supplied to a first portion of the supply and discharge passage (7) which is close to the supply and discharge port (6) exceeds a set pressure, the pressurized oil moves the valve member (26) rightward for valve opening, against the pressure-setting spring (31).

A manipulator for concrete pumps having an articulated boom with at least two boom arms and a hydraulic drive that pivots one or more of the boom arms. A hydraulic cylinder has piston and rod side working volumes. A hydraulic circuit has a first switching state in which the hydraulic circuit connects a first working port for feed or discharge of hydraulic fluid to the rod-side working volume and connects a second working port for feed or discharge of hydraulic fluid to the piston-side working volume. In a second switching state, the hydraulic circuit separates the first working port from the first fluid channel and thereby connects the first fluid channel to the second fluid channel for the feed of hydraulic fluid from the rod-side to the piston side working volume. A sensor acquires an operating state variable based upon which an activation assembly sets the switching state.

A mast assembly that includes a mast and a hydraulic circuit for moving the mast. The hydraulic circuit includes a primary hydraulic cylinder coupled to the mast to rotate the mast about a pivot axis and a secondary hydraulic cylinder extending from a rod end to a cap end that is fluidly coupled to the primary hydraulic cylinder. A directional valve is fluidly coupled between the primary hydraulic cylinder and secondary hydraulic cylinder to keep a pressure on the cap end of the secondary hydraulic cylinder greater than the pressure on the rod end of the secondary hydraulic cylinder during all operating conditions.

Provided is a construction machine allowing regeneration of a return hydraulic fluid at the time of both a boom raising operation and a boom lowering operation with a small number of valves, making it possible to secure a satisfactory operability at the time of both the boom raising operation and the boom lowering operation. The construction machine includes: a first hydraulic actuator; a second hydraulic actuator; a tank; and a first hydraulic pump supplying a hydraulic fluid to the second hydraulic actuator, the construction machine further including: a return hydraulic fluid selection device selecting a supply source of a return hydraulic fluid generated at a time of a raising operation or a lowering operation of the first hydraulic actuator and discharging the return hydraulic fluid; a regeneration line supplying the hydraulic fluid discharged from the return hydraulic fluid selection device to a portion between the second hydraulic actuator and the first hydraulic pump to regenerate the hydraulic fluid; a discharge line discharging the hydraulic fluid discharged from the return hydraulic fluid selection device to the tank; and a regeneration/discharge flow rate adjustment device capable of adjusting a flow rate of the hydraulic fluid flowing through the regeneration line and a flow rate of the hydraulic fluid flowing through the discharge line.

A regulator valve has a check valve manifold for use in subsea control circuits. For example, the regulator valve having the check valve manifold can be used in a circuit between a directional control valve and an actuator for a gate valve. The check valve manifold can be a flange that attaches to the regulator valve to communicate with the supply and outlet of the regulator valve. Internal communication inside the manifold includes a check valve. If the pressure in the circuit downstream of the regulator valve needs to be vented, the check valve can open to allow the pressure to bleed from the outlet back to the supply without needing to pass through the internal pressure control valve of the regulator.

A hydraulic cylinder includes a cylinder having axially spaced-apart first and second bores, and a piston having a piston rod and arranged in the cylinder for movement between two end positions and dividing the cylinder into a piston side and a piston-rod side. A hydraulic pump pumps hydraulic oil into the piston side to move the piston from one end position toward the other end position while hydraulic fluid is discharged from the piston-rod side via the first bore and a first outlet line. A throttling device is operably connected to the cylinder to throttle a flow of the hydraulic fluid as the piston moves past and seals the first bore so that hydraulic fluid is discharged via the second bore, thereby reducing a delivery amount of the hydraulic oil and thereby braking and damping a movement of the piston toward the other one of the end positions.

An actuated valve system includes a valve including a flow controlling valve element, an actuator assembled with the valve and including an inlet port in fluid communication with a fluid driven actuator member operatively connected with the valve element and movable from a normal position to an actuated position in response to pressurization of the inlet port to at least a minimum actuating pressure, a pilot valve operable to supply pressurized fluid to the actuator inlet port in a first position and to exhaust pressurized fluid from the actuator inlet port through an exhaust port in the pilot valve in a second position, and a backpressure arrangement in fluid communication with the actuator inlet port to retain a positive pressure smaller than the minimum actuating pressure against the actuator member when the pilot valve is moved to the second position.

A regulator valve has a check valve manifold for use in subsea control circuits. For example, the regulator valve having the check valve manifold can be used in a circuit between a directional control valve and an actuator for a gate valve. The check valve manifold can have a flange that attaches to the regulator valve to communicate with the supply-side and outlet-side of the regulator valve. Internal communication inside the manifold includes a check valve. If the pressure in the circuit downstream of the regulator valve needs to be vented, the check valve can open to allow the pressure to bleed from the outlet-side back to the supply-side without needing to pass through the internal pressure control valve of the regulator.

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.