A system and method for detecting the functional state of a piloted or direct-operated isolation valve in a hydraulic circuit is presented. In some examples the hydraulic circuit is a steering circuit and the isolation valve provides selective isolation between a hydraulic actuator and one or more metering valves. In some examples, the isolation valve assembly is movable between a first position, in which fluid flow between the metering valve and the actuator is enabled, and a second position, in which fluid flow between the metering valve and the actuator is blocked. When the isolation valve assembly is moved to one of the first and second positions, an inlet port and a pressure sensing port of the isolation valve assembly are placed in fluid communication with each other. When the isolation valve assembly is moved to the other of the first or second position, a second inlet port and the pressure sensing port are placed in fluid communication.

A flow rate controller and a drive device are provided with a cylinder flow passage connected to an air cylinder; a main flow passage for supplying air to and discharging air from the air cylinder; an auxiliary flow passage that has a first throttle valve and through which exhaust air discharged from the air cylinder passes with a smaller flow rate than that of the main flow passage; a switch valve that switches between a first position in which the cylinder flow passage communicates with the main flow passage and a second position in which the cylinder flow passage communicates with the auxiliary flow passage; and a pilot air adjustment part that guides a portion of the exhaust air from the air cylinder as pilot air to the switch valve.

A high-pressure unit (HPU) skid for greasing and actuating a frac tree valve includes one or more hydraulic pumps, a grease pump, a hydraulic reservoir, and two or more accumulators all of which are mounted on a portable frame. The HPU skid further includes fluidic connections to connect the frac tree valve to an output of the grease pump and fluidic connections to connect the frac tree valve to at least one of the two or more accumulators. The hydraulic pumps are configured to withdraw hydraulic fluid from the hydraulic reservoir for charging the accumulators, operating the grease pump, or charging the accumulators and operating the grease pump at a same time.

A hydraulic system for controlling an implement on a work machine may include a hydraulic reservoir, a hydraulic pump in fluid communication with the reservoir, a central valve in fluid communication with the pump and configured for controlling the implement, a pressure relief system arranged in fluid communication with the hydraulic pump and the central valve, and a controller. The controller may be configured for controlling the hydraulic pump, the central valve and the pressure relief system and selecting between operating the hydraulic system at a first pressure and a second pressure based on a factor relating to implement position.

A hydraulic system for a working machine includes hydraulic actuators actuated with hydraulic fluid delivered from a hydraulic pump, control valves each of which is shiftable among shift positions to control a flowrate of hydraulic fluid flowing to the corresponding hydraulic actuator, a detection fluid passage, an interlocking control valve, and a pressure detection unit. Each control valve includes an input port, an output port, and a flowrate reduction section. One of the control valves includes a flowrate increase section. The interlocking control valve is configured to be shifted in accordance with a shift of the one of the control valves among the shift positions and to be shifted to a blocking position to block a pilot fluid introduced into the interlocking control valve from the detection fluid passage when the one of the control valves is shifted to the increase position.

A hydraulic system includes: an arm hydraulic cylinder; a first hydraulic pump and a second hydraulic pump; an arm first direction switching valve; an arm second direction switching valve; and a controller that controls an operation of the arm second direction switching valve when the arm hydraulic cylinder is extended and operated. Further, the arm first direction switching valve incorporates an arm regeneration passage capable of supplying oil when the arm hydraulic cylinder is extended and operated, and the controller monitors a pressure state of the arm hydraulic cylinder, and when determining that oil flow through the arm regeneration passage is possible, the controller blocks oil flow between the arm hydraulic cylinder and the arm second direction switching valve, and otherwise, the controller operates the arm second direction switching valve so that oil can be supplied from the second hydraulic pump to the bottom chamber.

A working machine includes a machine body, a first hydraulic actuator mounted on the machine body, a first control valve that controls the first hydraulic actuator, a controller that controls the first control valve, and a second hydraulic actuator that is different from the first hydraulic actuator. When the second hydraulic actuator and the first hydraulic actuator are operated in combination, the controller reduces the amount of change in the flow rate of a hydraulic fluid supplied from the first control valve to the first hydraulic actuator with respect to changes in a manipulation amount to operate the first hydraulic actuator to a value smaller than that when the first hydraulic actuator is solely operated.

A method of controlling an actuator includes switching a primary solenoid valve to a first mode to fluidically connect a supply pressure source to a control chamber of a pilot valve. A fluid from the supply pressure source is directed through the primary solenoid valve to fill the control chamber of the pilot valve and put the pilot valve in a first position. The first position fluidically connects a second chamber of the actuator to a return pressure source. The actuator includes a cylinder between the first chamber and the second chamber and a rod attached to the cylinder. The fluid from the supply pressure source is directed into the first chamber of the actuator to move the cylinder and the rod in a first direction while the pilot valve is in the first position.

A valve device that changes the direction of flow of a hydraulic fluid supplied to and discharged from a cylinder mechanism to actuate the cylinder mechanism, the valve device including: a control valve including a main spool axially movable between different positions; a lock valve including a plunger and a pressure chamber; and a selector valve including a selector spool operable in conjunction with the main spool to axially move between different positions, the selector spool being located adjacent to the main spool and having an axis crossing an axis of the main spool.

A hydraulic system for a working machine, the hydraulic system includes: a hydraulic fluid reservoir; a boom actuator having an ascending chamber and a descending chamber; a first pump; a first directional control valve comprising a first ascending state configured for moving the boom in the ascending direction, a descending state configured for moving the boom actuator in the descending direction, and a first neutral state; a second pump; a second directional control valve comprising a second ascending state configured for moving the boom actuator in the ascending direction, and a second neutral state; wherein the second directional control valve further comprises a float state configured to connect at least one of the ascending and descending chambers to the hydraulic reservoir for permitting the boom to move freely in the descending and/or descending directions.