[Object] To make it possible to detect, with a single pressure sensor, a malfunction of two solenoid valves for switching flow paths and to quickly and reliably exhaust residual pressure in an air device through a solenoid valve.

[Solution] A residual pressure exhaust air circuit 1 includes: a main flow path 9 through which air from an air source 2 is supplied to an air cylinder 100; an exhaust flow path 10 through which air in the air cylinder 100 is exhausted; a first sensor 8 for detecting a malfunction of solenoid valves 12, 13; a detection flow path 11 through which air from the air source 2 is supplied to the first sensor 8; and the two solenoid valves 12, 13 that switch communication states among the main flow path 9, the exhaust flow path 10, and the detection flow path 11. The two solenoid valves 12, 13 are formed of two-position valves having first positions 12a, 13a at the time of OFF and second positions 12b, 13b at the time of ON and are synchronously ON/OFF controlled. When the two solenoid valves 12, 13 do not operate in synchronization with each other, the air from the air source 2 is supplied to the first sensor 8 to detect a malfunction of the two solenoid valves 12, 13, and at the same time, the air in the air cylinder 100 is exhausted through the solenoid valve 12, 13.

A construction machine incorporates a hydraulic closed circuit system capable of suppressing, even where a selector valve is stuck in an open state by a failure of the selector valve or a control system therefor, unintended operation of a hydraulic actuator and continuing operation of a machine body. The construction machine includes first sensors that detect open-closed states of a plurality of switching valves, first compulsory valve closing devices that change over the plurality of switching valves to a closed position irrespective of open-close control by a machine body controller, and a valve device controller that controls, when it is detected based on the open-closed states of the plurality of selector values detected by the first sensors that one of the plurality of selector values is stuck in an open state, the first compulsory valve closing device such that other selector valve connected to one of the plurality of closed circuit pumps to which the one selector valve is connected is closed.

A proportional valve is provided having a pilot control valve that can be controlled by means of a control signal and having a booster valve that can be actuated by means of the pilot control valve. The proportional valve has a compressed-air connection for connecting a compressed-air supply, a working connection, and an air-removal connection. The booster valve has three valve elements, which are arranged one after the other and can each be moved in an axial direction against a spring force.

A valve unit has a main valve and a pilot valve device which is applied thereto, wherein the pilot valve device includes a first pilot valve which is arranged in a valve longitudinal direction between the main valve and a second pilot valve. The main valve can be actuated by way of a pilot fluid through a first pilot working channel which is connected to the first pilot valve and through a second pilot working channel which is connected to the second pilot valve. The second pilot working channel passes through a first pilot valve housing of the first pilot valve, wherein it has a receiving space channel section which passes through an actuation member receiving space of a hand actuation device which is formed in the first pilot valve housing and in which a manually actuatable hand actuation member is arranged. In this manner the valve unit can be realised with a low construction width.

A valve includes an inlet and an outlet; a body including a first seat and a second seat; a cavity in the body; a piston positioned in the cavity; and a pilot ball adjacent the piston and that is disposed in a pilot seat, and a rear surface of the piston butts against the pilot seat at a maximum open position of the piston. Each of the first seat and the second seat is a seat that is a mechanical stop that prevents the piston from extending further than the closed position. The piston includes a flat front face that contacts the first seat when in the closed position, and a nose extension that extends outward and away from a center portion of the front face, and the nose extension has an opening through a center of a front surface thereof.

The present invention provides an unloading valve assembly that configures a compression area divided for each control input and opens a valve seat by a pressurizing rod of a piston that performs pressurization by a control input, thereby quickly and accurately exhausting compressed air through the unloading valve assembly and improving durability when closing the valve.

Hydraulic valves for dampening pressure spikes and associated methods are disclosed herein. In one embodiment, a hydraulic valve for dampening pressure spikes includes: a spool configured to move axially inside the hydraulic valve; and a sleeve configured to at least partially house the spool. A location of the spool with respect to the sleeve may determine a flow of a working fluid through the hydraulic valve. A viscous damper is at least partially housed inside an opening in the spool, and a viscous friction between the viscous damper and the opening in the spool slows a motion of the spool.

A solenoid valve manifold (10) includes a connector member (70) that is formed by integrating a base portion (71) with a first connector portion (80) configured to electrically connect a first conductive member (52) to a circuit board (41) and a second connector portion (90) configured to electrically connect a second conductive member (62) to the circuit board (41). The base portion (71) has a through-hole (72). The base (30) includes two engagement projections (46). The base portion (71) is elastically deformable in a direction intersecting an insertion direction when the two engagement projections (46) are inserted into the through-hole (72). The connector member (70) is configured to be attached to the base (30) when a part of the base portion (71) around the through-hole (72) is engaged with the two engagement projections (46).

A system and method for controlling a remote valve includes temporarily driving or activating a battery-powered pilot valve assembly to place an operatively coupled output valve in a switch position. One or more processors receives a temperature measurement associated with an operating environment of the battery-powered pilot valve assembly, compares the received temperature measurement to a temperature threshold level, and continuously drives the battery-powered pilot valve assembly to maintain the output valve in the switch position if the temperature measurement is below the temperature threshold level.

A mode valve includes a spool axially moveable within a sleeve in response to a control (e.g. hydraulic or electro-mechanical) command. The spool includes channels and lands, and the sleeve comprising ports in fluid communication with a hydraulic fluid supply and ports in connection with control chambers of an actuator responsive to the valve. The valve also includes first drive means for moving the spool, relative to the sleeve, between a first position, and a second position in which fluid flow from the fluid supply to the actuator chambers through the valve is blocked and wherein a fluid path with a first pressure drop is defined in the mode valve for fluid flow between actuator chambers; the mode valve comprising second drive means for moving the spool relative to the sleeve to a third position in which fluid flow from the fluid supply to the actuator chambers is blocked.