A plurality of detection valves (12 and 13) are provided to a housing (1), and at least one air passage (14 and 15), which communicatively connects the detection valves (12 and 13) to each other in series, are provided to the housing (1). One or some of the detection valves (12 and 13) are each configured as a throttle detection valve (13) including a throttle passage (56a).

A pressure booster constituting a cylinder apparatus is provided with a first piston and a second piston that are coupled to each other by a rod. A connection member provided to the second piston is configured so as to be displaceable from a connection position to a blocking position as a result of the connection member making contact with a cylinder body when the second piston is displaced in a direction where a boosting chamber contracts, and so as to be displaceable from the blocking position to the connection position as a result of the connection member making contact with the cylinder body when the second piston is displaced in a direction where the boosting chamber expands.

When pressurized fluid is not supplied into or discharged from the first channel 28a of the piston rod 28, that is, when the first channel 28a is isolated from the outside, the cylinder tube 22 is in a stopped state. At this time, fluid inside the first cylinder chamber 36a is compressed, and the pressure is increased accordingly to match the sum of the weights of the cylinder tube 22, the table 18, and the workpiece W.

A double-acting overflow valve of a working cylinder includes a housing with an encompassing wall and a first and a second axial delimiting wall disposed opposite one another. A first valve body has a first valve tappet with a conical shape and passes through the first axial bore to define a first annular gap with a gap width that is dependent on a position of the first valve body along an actuation path thereof. A second valve body has a second valve tappet with a conical shape and passes through the second axial bore to a second annular gap with a gap width that is dependent on a position of the second valve body along an actuation path thereof. A first and second counter bearing are provided. A first actuating element defines a maximum actuation path of the first valve body by acting on the first counter bearing. A second actuating element defines a maximum actuation path of the second valve body by acting on the second counter bearing. A first spring applies an axial force to the first valve body in a direction of the closed position of the first valve disk. A second spring applies an axial force to the second valve body in a direction of the closed position of the second valve disk.

A system for providing pressure/load control at an end stroke stop is provided. The system includes an actuator housing having an end stroke stop and a first actuator housing side, an actuator piston provided in the actuator housing, wherein the actuator piston is movable along a longitudinal axis (A), the actuator piston having a first piston portion perpendicular to the longitudinal axis (A), and means for regulating the pressure/load control at the end stroke stop provided in the first piston portion, wherein the means for regulating the pressure/load control at the end stroke stop is configured to move from a closed position to an open position when in contact with the first actuator housing side.

A technique facilitates rapid transitioning of a valve, e.g. a gate valve. According to an embodiment, a system comprises a valve actuator constructed for coupling with a valve to actuate the valve between closed and open positions. Hydraulic actuation fluid may be supplied to the valve actuator under pressure via a hydraulic supply system to enable selective shifting of the valve actuator, and thus the valve, from a closed position to an open position. The system also comprises a dump tank coupled to the valve actuator in a manner to receive hydraulic fluid. In a rapid valve actuation operation, e.g. closing operation, the dump tank receives hydraulic fluid from the valve actuator rather than returning the hydraulic fluid to the hydraulic supply system. This, in turn, enables rapid shifting of the valve actuator and thus rapid shifting of the valve.

A double-acting overflow valve of a working cylinder includes a housing with an encompassing wall and a first and a second axial delimiting wall disposed opposite one another. A first valve body has a first valve tappet with a conical shape and passes through the first axial bore to define a first annular gap with a gap width that is dependent on a position of the first valve body along an actuation path thereof. A second valve body has a second valve tappet with a conical shape and passes through the second axial bore to a second annular gap with a gap width that is dependent on a position of the second valve body along an actuation path thereof. A first and second counter bearing are provided. A first actuating element defines a maximum actuation path of the first valve body by acting on the first counter bearing. A second actuating element defines a maximum actuation path of the second valve body by acting on the second counter bearing. A first spring applies an axial force to the first valve body in a direction of the closed position of the first valve disk. A second spring applies an axial force to the second valve body in a direction of the closed position of the second valve disk.

The invention relates to a hydraulically actuated piston (9) guided in a cylinder (8), and to a hydraulic working tool (1) having a working head (2), wherein the piston (9) has an impact surface (15) which borders an impact space (16) on the piston side provided between the piston (9) and the cylinder (8), and wherein hydraulic fluid (17) can act on the impact surface (15) by increasing the impact space (16) in order to move the piston (9) in an impact direction (r), and the piston (9) forms a limiting device (25) for a through-flow of the hydraulic fluid (17). According to the invention, in order to design a hydraulic piston guided in a cylinder or a hydraulic working tool in such a way that no undue signs of wear occur even during working processes with the sudden disappearance of the counter pressure, a hydraulic chamber (19) filled with the hydraulic fluid (17) is formed in the impact direction (r) after the limiting device (25), wherein a volume of the hydraulic chamber (19) is reduced according to the increase in the impact space (16), by means of the displacement of hydraulic fluid (17) out of the hydraulic chamber (19) and into the impact space (16) via the limiting device (25).

In a hydraulic drive of a tool piston in a cylinder first and second flat contact areas each are contiguous, when moving into and in the open position of the valve member between the detent element and the valve member, wherein a pressure-limiting valve that can be loaded with the pressure in the cylinder from a closed position to an open position and a detent element loaded by a spring in the locking direction to positively hold a neck of a valve member of the pressure-limiting valve are arranged in the open position, wherein the detent element at least via the tool piston at its return to a released position can be moved and, when moving the valve member to the open position of the pressure-limiting valve, non-positively acts on the valve member.

In one aspect, a piston assembly for a fluid-driven actuator may include a piston defining a passage extending between first and second chambers of the actuator. The piston assembly may further include a valve having a valve head and a valve stem. The valve may be positioned within the passage and slidable between an open position and a closed position. The valve stem may extend outward from the passage into the second chamber when the valve is positioned in the closed position. Additionally, the piston assembly may include a spring compressed between the valve head and the piston. The spring may be configured to bias the valve to the closed position. The valve may be configured to move to the open position when a pressure in the second chamber exceeds a pressure threshold or when the valve stem contacts a cylinder of the fluid-driven actuator.