A speed controller is capable of being applied to a cylinder with a short stroke with a simple structure. The speed controller includes a first flow channel and a second flow channel allowing a first port and a second port to communicate with each other, into which pressure fluid is allowed to flow, in which a first valve is arranged in the first flow channel, a second valve is arranged in the second flow channel, a third flow channel and a fourth flow channel are further included, and a third valve is arranged in the third flow channel, allowing only flowing from the first port toward a portion on the piston shaft side with respect to a piston in a cylinder chamber in the third flow channel as well as closing the first flow channel and the fourth flow channel by moving a third valve body in a direction of opening the third flow channel, and opening the first flow channel and the fourth flow channel by moving the third valve body in a direction of closing the third flow channel.

A hydraulic lifting mechanism suspension has a main valve in the activation position whereof at least one hydraulic accumulator is connected to a connection line of the lifting mechanism suspension acting in the lifting direction or to working line of the lifting mechanism suspension acting in the lifting direction. The lifting mechanism suspension is deactivated via a deactivation position of the main valve, while at the same time a connection for recharging or filling the hydraulic accumulator is opened.

Embodiments of the present invention disclose a valve. The valve includes: a valve casing, a main valve spool and a counterbalance valve spool. The counterbalance valve spool is disposed in a main valve spool internal cavity of the main valve spool and is slidable between a first counterbalance valve spool position and a second counterbalance valve spool position. The counterbalance valve spool includes: a counterbalance valve spool body; and a first counterbalance valve spool recess formed on an outer periphery of the counterbalance valve spool body. In a state where the counterbalance valve spool is in the first counterbalance valve spool position, an inlet of an outlet passage of the main valve spool is closed by the counterbalance valve spool; and in a state where the counterbalance valve spool is in the second counterbalance valve spool position, the inlet of the outlet passage of the main valve spool is opened by the counterbalance valve spool through the first counterbalance valve spool recess of the counterbalance valve spool, so that a second working port is in communication with a return port through an inlet passage configured for the second working port, the first counterbalance valve spool recess and the outlet passage.

A pressure compensation unit includes: a control valve controlling hydraulic fluid supply and discharge to and from an actuator, the control valve including a pump port, a pair of relay and supply/discharge ports, and a tank port; a pressure compensation valve connected to the relay ports by an upstream and downstream-side relay lines, the pressure compensation valve moving in accordance with a pressure difference between upstream-side relay line and signal pressure; a load pressure detection line branching from the downstream-side relay line; a relief line connected to the downstream-side relay line and having a relief valve; and a switching valve leading: a maximum load pressure to the pressure compensation valve as the signal pressure when the hydraulic fluid does not flow through the relief line; and a pump pressure to the pressure compensation valve as the signal pressure when the hydraulic fluid flows through the relief line.

A fluid power system comprises a pump with multiple independently variable outlets, each of which is capable of delivering fluid in individually controllable volume units and a plurality of hydraulic loads. A system of switching valves is configured to create fluid connections between the pump outlets and the loads. A control system commands both the pump and the switching valves, so as to create valve state combinations to satisfy load conditions as demanded by an operator. The number of pump outlets connected to one or more of the loads is changeable to satisfy the flow required of the load due to the operator demand, each pump outlet being commanded to produce a flow depending on the status of other outlets connected a load to which the outlet is connected and the operator demand for that load.

A hydraulic system includes a pump in communication with a fluid reservoir and powered by a motor. A pressure compensator is adapted to adjust a position of a variable displacement mechanism of the pump. A load sensing line is adapted to communicate a highest load sensing pressure from a plurality of valves to the pressure compensator. The pressure compensator adjusts the variable displacement mechanism of the pump based on the highest load sensing pressure for maintaining a constant pressure drop across one or more work ports in each of the plurality of valves. The plurality of valves each include a load sense port having an integrated check valve that includes a metering orifice.

A fluid power system comprises a pump with multiple independently variable outlets (11, 12, 13, 14), each of which is capable of delivering fluid in individually controllable volume units and a plurality of hydraulic loads (15, 16, 18, 20). A system of switching valves is configured to create fluid connections between the pump outlets and the loads. A control system commands both the pump and the switching valves, so as to create valve state combinations to satisfy load conditions as demanded by an operator. The number of pump outlets (11, 12, 13, 14) connected to one or more of the loads (15, 16, 18, 20) is changeable to satisfy the flow required of the load due to the operator demand, each pump outlet being commanded to produce a flow depending on the status of other outlets connected a load to which the outlet is connected and the operator demand for that load.

A pressure compensation unit includes: a control valve controlling hydraulic fluid supply and discharge to and from an actuator, the control valve including a pump port, a pair of relay and supply/discharge ports, and a tank port; a pressure compensation valve connected to the relay ports by an upstream and downstream-side relay lines, the pressure compensation valve moving in accordance with a pressure difference between upstream-side relay line and signal pressure; a load pressure detection line branching from the downstream-side relay line; a relief line connected to the downstream-side relay line and having a relief valve; and a switching valve leading: a maximum load pressure to the pressure compensation valve as the signal pressure when the hydraulic fluid does not flow through the relief line; and a pump pressure to the pressure compensation valve as the signal pressure when the hydraulic fluid flows through the relief line.

A load sense passage in a load sense hydraulic system may be vented by allowing flow from the load sense passage to a reservoir via a drain passage when a first flow control valve is in a neutral position. This venting may be prevented by preventing flow from the load sense passage to a reservoir via the drain passage when the first flow control valve is in a flow-allowing position.

The invention relates to a hydraulic valve device (1) including a high pressure connection (P) and a low pressure connection (T); at least one motor port connection (A) that is connectable to a motor port (A) on a hydraulic motor (M), preferably a hydraulic cylinder; a flow control valve (F), which is arranged between the high pressure connection (P) and the motor port connection (A) and which includes a flow opening (18) that is adjustable between a fully closed position and a fully open position; and a pressure regulator (R) that is arranged between the high pressure connection (P) and the flow regulating valve (F), wherein a regulator pressure (PR) that acts at a first connection point (3) between the pressure regulator (R) and the flow regulating valve (F) acts on the pressure regulator (R) via a first control conduit (4) to close the same. A second control conduit (5) including a first restrictor (6), is arranged to convey a load pressure (PL) that acts at the motor port connection (A) from a second connection point (7) positioned between the flow regulating valve (F) and the motor port connection (A) via the first restrictor (6) to a third connection point (8) at which a first control pressure (Pc) acts and which third connection point (8) is connected to the pressure regulator (R) to act on the same in the opening direction by means of said first control pressure (Pc), wherein the third connection point (8) is connected to the low pressure connection (T), via an adjustable second restrictor (9).