A hydraulic system includes: a solenoid valve that includes a valve spool configured to slide within a housing, and moves the valve spool to a position corresponding to an operation command input to the solenoid valve; and a control device that outputs the operation command to the solenoid valve. When a predetermined condition is satisfied, the control device outputs a continuously or intermittently changing operation command to the solenoid valve to reciprocate the valve spool from a full open position or a full closed position.

A hydraulic system includes: a solenoid valve that includes a valve spool configured to slide within a housing, and moves the valve spool to a position corresponding to an operation command input to the solenoid valve; and a control device that outputs the operation command to the solenoid valve. When a predetermined condition is satisfied, the control device outputs a continuously or intermittently changing operation command to the solenoid valve to reciprocate the valve spool from a full open position or a full closed position.

A hydraulic lockout lever failure detection system preferably includes a first analog sensor, a second analog sensor, at least one electronic control module (ECU) and a solenoid valve. The voltage output level of the first and second analog sensors is monitored by the ECU. The solenoid valve controls the flow of hydraulic fluid to operate an excavator or other equipment. The operation of the solenoid valve is controlled by the ECU. However, a second ECU may be used to control the operation of the solenoid valve. A hydraulic lockout lever causes the first and second analog sensors to output either a low voltage to indicate a closed position, or to indicate an open position to the ECU. If the first and second analog sensors output a voltage that is above a low set value or above a high set value, a fault is detected.

A directly-controlled hydraulic directional valve includes a housing, control piston, first and second springs, double-stroke solenoid, spring plate, adjustment device, and electronics. The piston is longitudinally displaceable in a bore in the housing, either directly or via a control sleeve. The springs are positioned in a region of an end of the piston remote from the solenoid. One end of each spring is supported on the spring plate, which is clamped between the springs and the piston. The other end of the first spring is fixed to the housing, and the other end of the second spring is fixed to the adjustment device. The first spring exerts a force on the piston in a first direction, and the second spring exerts a force on the piston in a second opposite direction, so as to bias the piston into a preferred position. The solenoid is mounted on a side of the housing, and is operable to move the piston out from the preferred position in opposite directions proportional to an electric current from the electronics, such that the piston moves to the preferred position in response to each of non-actuation of the solenoid and a fault in the electronics. The adjustment device is operable to alter a position of the other end of the second spring to adjust the preferred position of the piston.

A gas-powered drive system has a drive which includes a first chamber and a second chamber which are separated from one another by a piston. One of the chambers is connected to a gas source to drive the work element and the other chamber is connected via an exhaust air throttle to a gas sink by means of a reversing valve to movement of the piston. A control valve is assigned to the driving chamber through which the driving chamber can be filled with gas from the gas source. The opening cross-section of the control valve is set as a function of a control pressure.

A gas-powered drive system has a drive which includes a first chamber and a second chamber which are separated from one another by a piston. One of the chambers is connected to a gas source to drive the work element and the other chamber is connected via an exhaust air throttle to a gas sink by means of a reversing valve to movement of the piston. A control valve is assigned to the driving chamber through which the driving chamber can be filled with gas from the gas source. The opening cross-section of the control valve is set as a function of a control pressure.

A brake driving apparatus includes a hydraulic valve block including a vent channel for discharging air to the outside, an electronic control device that includes an electrical component housing open in a direction of the vent channel of the hydraulic valve block and having a ventilation hole connected to an internal space and a filter attached to the electrical component housing to block the ventilation hole so that air can pass therethrough, and is supported by one side of the hydraulic valve block, and a vent sealing member that seals a space between the hydraulic valve block and the electronic control device and surrounds the vent channel, the ventilation hole, and the filter.

A rotary servo valve comprising a housing portion (105) defining a cylindrical cavity (107) and a first layer of ports. The rotary servo valve further comprises two opposing indented sides and two opposing sides having an increased radius relative to the indented sides, each side of increased radius extending between the two indented sides. The spool portion (103) is mounted for rotation relative to the cylindrical cavity (107), from a neutral position so as to prevent fluid flow through the valve, to an open position in which a fluid flow path is provided.

A rotary servo valve comprising a housing portion (105) defining a cylindrical cavity (107) and a first layer of ports. The rotary servo valve further comprises two opposing indented sides and two opposing sides having an increased radius relative to the indented sides, each side of increased radius extending between the two indented sides. The spool portion (103) is mounted for rotation relative to the cylindrical cavity (107), from a neutral position so as to prevent fluid flow through the valve, to an open position in which a fluid flow path is provided.

A control device for controlling a hydraulic consumer (2), such as a working cylinder, has at least one control valve (18) having a control spool (20). Control spool (20) is guided in a valve housing (22) in a longitudinally movable manner and is actuated by an electric motor (24). Electric motor (24) can be controlled by control electronics (MC), which receive input signals from a sensor device (58, 60, 62) detecting at least one operating state of the consumer (2).