A hydraulic device having: a plurality of main piston-cylinder arrangements, each of the respective pistons having a fixed stroke length and configured for axial reciprocation within their respective cylinder; a plurality of flow control valves for switching between a lockdown state and an unlocked state of one or more of the plurality of main piston cylinder arrangements during operation of the hydraulic device; and one or more control valves for directing the plurality of flow control valves between their respective unlock and lock positions.

An actuator includes a housing defining an inlet port, a piston and a return spring disposed within the housing, and an elastically deformable element. The return spring is configured to apply a biasing force to the piston to move the piston to a spring return position. A first fluid pressure applied to the inlet port moves the piston against the biasing force of the return spring to a first actuated position in which the piston indirectly engages a stop portion of the actuator housing. A second fluid pressure, greater than the first fluid pressure, applied to the inlet port moves the piston against the elastically deformable element to compress the elastically deformable element to move the piston to a second actuated position beyond the first actuated position.

A switching valve includes a sleeve on which a plurality of ports are disposed; a spool that is disposed inside the sleeve to move in an axial direction by a pilot hydraulic pressure to switch between switching lines each serving as a flow channel for hydraulic fluid that is formed by a combination of the ports; a first energizing unit that energizes the spool against the pilot hydraulic pressure; a relief hole that is disposed on the spool to discharge the hydraulic fluid with the pilot hydraulic pressure; a valve body that closes the relief hole; and a second energizing unit that energizes the valve body toward the relief hole of the spool against the pilot hydraulic pressure, and when the pilot hydraulic pressure exceeds a predetermined value, opens the relief hole.

Actuator systems and methods of operation are disclosed. The systems include a hydraulic actuator having a primary piston having a piston head arranged within a housing defining retract and extend chambers on opposite sides of the piston head. A control element is configured to control a supply of pressure to each of the retract and extend chambers. An actuator valve is coupled to the housing and includes a secondary piston that is biased into the retract chamber in an open flow state and when the primary piston is in a fully retracted state the piston head urges the secondary piston into a closed flow state. The actuator valve defines a flow chamber where, in an open flow state, fluid can be passed through the flow chamber and in a closed flow state the fluid is prevented from passing through the flow chamber.

A hydraulic device having: a plurality of main piston-cylinder arrangements, each of the respective pistons having a fixed stroke length and configured for axial reciprocation within their respective cylinder; a plurality of flow control valves for switching between a lockdown state and an unlocked state of one or more of the plurality of main piston cylinder arrangements during operation of the hydraulic device; and one or more control valves for directing the plurality of flow control valves between their respective unlock and lock positions.

An actuator includes a housing defining an inlet port, a piston and a return spring disposed within the housing, and an elastically deformable element. The return spring is configured to apply a biasing force to the piston to move the piston to a spring return position. A first fluid pressure applied to the inlet port moves the piston against the biasing force of the return spring to a first actuated position in which the piston indirectly engages a stop portion of the actuator housing. A second fluid pressure, greater than the first fluid pressure, applied to the inlet port moves the piston against the elastically deformable element to compress the elastically deformable element to move the piston to a second actuated position beyond the first actuated position.

An interlocked single function activation valve for hydraulic systems is disclosed. The hydraulic valve prevents unsafe tie-down or safety override situations by requiring the safety mechanism to be reset each time the hydraulic system is used. The hydraulic valve includes an interlock spool that moves to an extension position when the hydraulic system is de-pressurized and then re-pressurized while the control lever is engaged (i.e., tied down). When the interlock spool is in the extension position, it prevents the system from reaching a working pressure, thereby forcing a reset of the control lever before the system can reach working pressure.

An interlocked single function activation valve for hydraulic systems is disclosed. The hydraulic valve prevents unsafe tie-down or safety override situations by requiring the safety mechanism to be reset each time the hydraulic system is used. The hydraulic valve includes an interlock spool that moves to an extension position when the hydraulic system is de-pressurized and then re-pressurized while the control lever is engaged (i.e., tied down). When the interlock spool is in the extension position, it prevents the system from reaching a working pressure, thereby forcing a reset of the control lever before the system can reach working pressure.

A hydraulic control unit (4) includes a valve bush (12), a valve cover (15) partially closing the valve bush (12) on an end face (S1), a valve slide (13) guided in a longitudinal direction (L) within the valve bush (12), and a housing part (6). The housing part (6) includes a recess (8) matching an external contour of the valve bush (12). An intermediate plate (7) is configured to partially cover the valve cover (15). A spring (14) is arranged within the valve bush (12) and preloads the valve slide (13) in a starting position. The valve bush (12) is inserted, together with the valve cover (15), the valve slide (13), and the spring (14), into the recess (8) of the housing part (6) and jointly form a hydraulic valve (9). The valve bush (12) forms an inlet (19), and the valve cover (15) forms an outlet (31).

An easily installed and quick reacting in-line clutch engagement control device for hydraulically actuated power transmission friction clutches. The device allows a simple way to quickly and precisely limit a friction clutch's initial torque capacity to an easily adjustable pre-set level.