Some embodiments of the disclosure provide an advance and retreat automatic control method based on hydraulic sensing conversion and an advance and retreat automatic control system based on hydraulic sensing conversion, which includes an automatic advance and retreat device based on hydraulic sensing conversion, a motor, an oil cylinder, and/or an electric generator. When the digging motor encountered an overlarge resistance force, a pressure on the digging motor is instantaneously increased and exceeds a setting pressure value, hydraulic oil enters a hydraulic operated directional valve and pushes a valve rod to make the walking motor is reverse and retreat, an ultrahigh pressure state of the digging motor is released to restore to a normal pressure value to make reciprocated impact, the valve rod of the hydraulic operated directional valve is reset, and the walking motor is forwards rotated for advancing.

A hydraulic system arranged to control at least two hydraulic actuators via a metering control valve assembly. The hydraulic system is advantageous to control a pivoting arm of an undercutting mining machine according to at least two modes of operation including an idling mode and a cutting mode. In particular, the hydraulic actuators may be controlled by quantitative variation of fluid flow speed and pressure.

A wire pulling assembly for pulling a wire carrying tooling through an underground environment. The pulling assembly includes a cyclical vise carried by one or more hydraulic cylinders attached to a frame. The cylinders have a pulling stroke and a retraction stroke. A powered reel is used to store the wire as it is removed from the ground. During a pulling stroke, the reel is hydraulically isolated such that cable is stripped from the reel with tension maintained in the cable. During a retraction stroke, a motor turns the reel to load excess cable onto the reel.

This industrial apparatus (2) comprises a pneumatic system (4), a first mechanical device (36) and a second mechanical device (38). The pneumatic system (4) includes: a first pneumatic actuator (6) for commanding the first mechanical device (36), a second pneumatic actuator (8) for commanding the second mechanical device (38), a pneumatic control valve (10) switchable between several states to command of the first and second actuators (6, 8). The control valve (10) comprises an actuation portion (56), movable in translation between: a resting position, corresponding to a first state (51), a first pushed position, corresponding to a second state (S2), and a second pushed position, corresponding to a third state (S3). The first pushed position corresponds to an intermediary position between the resting position and the second pushed position.

An actuation chamber (2) provided in a housing (1) is communicatively connected to a supply and discharge port (6) via a pressurized oil supply and discharge passage (7). A valve case (11) of a sequence valve (10) is attached to an attachment hole (8) provided at an intermediate portion of the supply and discharge passage (7). A valve seat (25) is provided in a cylindrical hole (20) provided in the valve case (11). A valve member (26) is biased leftward toward the valve seat (25) by a pressure-setting spring (31). When pressure of pressurized oil supplied to a first portion of the supply and discharge passage (7) which is close to the supply and discharge port (6) exceeds a set pressure, the pressurized oil moves the valve member (26) rightward for valve opening, against the pressure-setting spring (31).

A hydraulic system for an air cart includes a primary hydraulic assembly and a secondary hydraulic assembly. The hydraulic system also includes a first valve configured to block a flow of a hydraulic fluid flowing in a first direction from the primary hydraulic assembly and a second valve configured to block a flow of the hydraulic fluid flowing in a second direction from the secondary hydraulic assembly.

An in-port sequencing valve configured to be utilized with a clamping device of a workpiece clamping system having a fixture plate, a number of fixture datums, and a number of clamping devices. The in-port sequencing valve includes a housing, a pre-load adjuster, a valve spring, and a valve piston. The pre-load adjuster is configured to be set to a selected valve activation setting. The valve spring is compressed an amount corresponding to the valve activation setting. The valve piston is configured to be shifted from a closed position to an open position when a force due to hydraulic fluid pressure overcomes a threshold spring force of the valve spring corresponding to the valve activation setting. The in-port sequencing valve can be set to a selected valve activation setting so that the clamping devices clamp the workpiece in a selected order according to the valve activation setting.

A hydraulic system for an air cart includes a primary hydraulic assembly and a secondary hydraulic assembly. The hydraulic system also includes a first valve configured to block a flow of a hydraulic fluid flowing in a first direction from the primary hydraulic assembly and a second valve configured to block a flow of the hydraulic fluid flowing in a second direction from the secondary hydraulic assembly.

A method of controlling a plurality of downhole tools in a wellbore, using first and second codes transmitted by hydraulic line to first address and then actuate the desired tool. A dedicated line is provided for terminating all actuated tools.

A hydraulic control circuit operable to selectively hydraulically link first and second hydraulic actuators and to bypass that hydraulic link.