The invention relates to a valve unit for the exclusive hydraulic actuation of the locking means of a mechanical quick-changer for attachments of a construction machine, wherein the valve unit comprises a feed pressure connector for applying the feed pressure, a first valve unit outlet for connecting an unlocking pressure line, a second valve unit outlet for connecting a locking pressure line, at least one discharge to the tank, and at least two switchable directional valves, with the feed pressure connector being connected or connectable to the second valve unit outlet via a serial connection of the at least two switchable directional valves.

A fluid power control system for load handling mobile equipment includes a pair of hydraulic actuators for moving respective cooperating load-engaging members selectively toward or away from each other, or in a common direction, at respective asynchronous speeds to selectively attain either synchronous or asynchronous respective positions of the actuators. The actuators have sensors enabling a controller to monitor their respective movements and correct unintended differences in the actuators' respective movements, such as unintended differences in relative intended positions, speeds, or rates of change of speeds. Respective hydraulic valves responsive to the controller separately and nonsimultaneously decrease respective flows through the respective actuators to more accurately and rapidly correct differences from the intended relative movements of the actuators.

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 fluid power control system for load handling mobile equipment includes a pair of hydraulic actuators for moving respective cooperating load-engaging members selectively toward or away from each other, or in a common direction, at respective asynchronous speeds to selectively attain either synchronous or asynchronous respective positions of the actuators. The actuators have sensors enabling a controller to monitor their respective movements and correct unintended differences in the actuators' respective movements, such as unintended differences in relative intended positions, speeds, or rates of change of speeds. Respective hydraulic valves responsive to the controller separately and nonsimultaneously decrease respective flows through the respective actuators to more accurately and rapidly correct differences from the intended relative movements of the actuators.

Provided is a construction machine allowing regeneration of a return hydraulic fluid at the time of both a boom raising operation and a boom lowering operation with a small number of valves, making it possible to secure a satisfactory operability at the time of both the boom raising operation and the boom lowering operation.

The construction machine includes: a first hydraulic actuator; a second hydraulic actuator; a tank; and a first hydraulic pump supplying a hydraulic fluid to the second hydraulic actuator, the construction machine further including: a return hydraulic fluid selection device selecting a supply source of a return hydraulic fluid generated at a time of a raising operation or a lowering operation of the first hydraulic actuator and discharging the return hydraulic fluid; a regeneration line supplying the hydraulic fluid discharged from the return hydraulic fluid selection device to a portion between the second hydraulic actuator and the first hydraulic pump to regenerate the hydraulic fluid; a discharge line discharging the hydraulic fluid discharged from the return hydraulic fluid selection device to the tank; and a regeneration/discharge flow rate adjustment device capable of adjusting a flow rate of the hydraulic fluid flowing through the regeneration line and a flow rate of the hydraulic fluid flowing through the discharge line.

A main winch system of a rotary drilling rig includes a main action loop, a pilot control loop, and a feedback control loop. The main action loop includes an engine, a hydraulic pump, a main control valve, a balance valve, a main winch motor, and an oil tank. The pilot control loop includes a pilot handle, a solenoid valve I, a pressure relay, and the main control valve in the main action loop. The feedback control loop includes a solenoid valve II and the hydraulic pump and the main control valve in the main action loop. In response to a lifting action of the pilot handle for the main winch, under the control of a button, the solenoid valve II is energized continuously, and the solenoid valve I is energized and de-energized according to a given rule.

An aircraft hydraulic valve includes a housing, a check valve, a valve opening component, and an auxiliary hydraulic pressure supply mechanism. The housing includes a first port communicated with a first chamber of a hydraulic actuator, a second port communicated with a switch valve bypass-communicating a second chamber of the hydraulic actuator with the first chamber, and an oil channel connecting the first and second ports. The check valve interrupts oil flow from the first port to the second port. The valve opening component is configured to open the check valve with pilot pressure supplied from the second chamber. The auxiliary hydraulic pressure supply mechanism obtains hydraulic pressure, for opening the check valve, from a closed hydraulic pressure section, which is defined in the oil channel between the check valve and the first port.

A hydraulic actuator control system includes a secondary manifold that is configured to direct a meter-in flow received from a main directional valve to the actuator and to direct a meter-out flow of fluid received from the actuator directly to a tank without the return flow travelling back through the main directional valve. The hydraulic actuator control system has a separate return flow connection that permits the use of a load-holding valve (such as, e.g., counterbalance valves, motion control valves, pilot-operated check valves, or zero-leakage logic elements) flanged on the machine's actuator (such as, e.g., a linear cylinder, a rotary cylinder, or a hydraulic motor) to create a directional control valve without directing the return flow through the main directional control valve.

A safety module for a process valve and a system comprising a safety module and a process valve are provided. The safety module comprises at least a first interface complementary to a first connection interface of a drive module of the process valve and a second interface complementary to a second connection interface of a process valve actuator of the process valve, such that the safety module can be retrofitted in the process valve. The safety module further comprises at least one safety valve and fluid lines provided for fluidically coupling the safety valve to the drive module and the process valve actuator of the process valve. The at least one safety valve of the safety module is configured for forced venting of the process valve in a safety case.

Example methods and apparatus independently control the seating force in a rotary valve. An example apparatus includes a rotary valve having a flow control member and a dual-acting actuator operatively coupled to the rotary valve. The actuator has first and second ports to receive a pressurized control fluid to change a position of the actuator. The example apparatus further includes a valve controller operatively coupled to the actuator to control the pressurized control fluid in response to a position of the rotary valve. The example apparatus further includes a pressure limiter operatively coupled to the valve controller and fluidly coupled to the first port of the actuator. The pressure limiter is to reduce a pressure of the pressurized fluid provided to the first port of the actuator to reduce a seating force of the flow control member when the rotary valve is in a closed position.