A main flow path that introduces high-pressure air to an air cylinder, or discharges exhaust air therefrom, includes a sub flow path provided alongside the main flow path; an exhaust flow rate adjustment unit that suppresses the operation speed of the air cylinder by adjusting the flow rate of the exhaust air flowing through the sub flow path; and a switching valve that is connected between the air cylinder, the main flow path and the sub flow path, and that connects the main flow path and the sub flow path to the air cylinder in a switching manner. The switching valve is constituted by a spool valve.

A shovel includes a lower traveling body, an upper traveling body turnably mounted on the lower traveling body, a hydraulic actuator, an operating apparatus configured to be operated to operate the hydraulic actuator, an object detector configured to detect an object within a predetermined area around the shovel, a gate lock lever configured to switch the operating apparatus between an enabled state and a disabled state, and a control device. The control device is configured to switch the operating apparatus between the enabled state and the disabled state separately from the gate lock lever, and to disable the operating apparatus in response to determining that the object is present within the predetermined area based on the output of the object detector while the operating apparatus is switched to the enabled state by the gate lock lever, during the standby state of the shovel.

A hydraulic system includes: a slewing motor; a mechanical brake; and a slewing control valve interposed between a main pump and the slewing motor. A first pilot port of the slewing control valve is connected to a first solenoid proportional valve by a pilot line. A second pilot port of the slewing control valve is connected to a second solenoid proportional valve by a second pilot line. The first solenoid proportional valve and the second solenoid proportional valve are connected to an auxiliary pump by a primary pressure line. A switching valve is interposed between the auxiliary pump and the mechanical brake. The switching valve includes a pilot port that is connected to the first pilot line by a switching pilot line. The valve switches from a closed to an open position when a pilot pressure led to the pilot port becomes higher than or equal to a setting value.

A hydraulic machine is provided. A boom actuator includes a large chamber and a small chamber. A recovery unit receives fluid discharged from the large chamber and then recovers energy. A recovery line connects the large chamber and the recovery unit. An accumulator is connected to the recovery line. A jack-up assist line connects the accumulator and the small chamber. A jack-up assist valve is disposed on the jack-up assist line to block flow of fluid from the accumulator to the small chamber in a first position and allow the flow of fluid from the accumulator to the small chamber in a second position. A controller controls movement of the jack-up assist valve. The controller may determine whether or not the hydraulic machine is in a jack-up condition, and when the hydraulic machine is determined to be in the jack-up condition, moves the jack-up assist valve to the second position.

A hydraulic machine. A boom actuator includes a large chamber and a small chamber. A recovery unit receives fluid discharged from the large chamber and then recovers energy. A recovery line connects the large chamber and the recovery unit. An accumulator is connected to a first point on the recovery line. A discharge valve is disposed on the recovery line between the first point and the recovery unit. A first sensor measures a pressure in the accumulator. A controller controls opening and closing of the discharge valve. The controller performs anti-bouncing control of: determining a target pressure in the accumulator corresponding to a load pressure applied to fluid in the large chamber by a load according to a predetermined correspondence; and controlling the opening and closing of the discharge valve such that the pressure in the accumulator measured by the first sensor reaches the target pressure.

A swing motion control system for an earth-moving machine may include a closed loop hydraulic circuit including a hydrostatic swing pump fluidly coupled to at least one hydraulic swing motor configured to control a swing mechanism of the earth-moving machine, a pressure control device configured to control the pressure of fluid supplied to the hydrostatic swing pump for control of the pressure output by the pump, and a controller. The controller may be configured to monitor and process signals received from sensors and operator input, wherein the signals received from the sensors are indicative of machine position and pose, and inertia mass of swing components and a payload being moved by the swing mechanism of the machine, and control at least one of an offset amount for desired pump displacement by the hydrostatic swing pump or an offset amount for pump output pressure from the hydrostatic swing pump based on at least one of an amount of slope on which the machine is operating or the inertia mass of the swing components and payload.

A system for controlling hydraulic fluid flow within a work vehicle includes a load sense valve configured to adjust the pressure of a bleed flow within a load sense conduit. Moreover, the system includes a computing system configured to determine the pressure of the hydraulic fluid within the fluid supply conduit downstream of the flow control valve based on the data captured by a pressure sensor. Furthermore, the computing device is configured to control an operation of the load sense valve to selectively adjust the pressure of the bleed flow within the load sense conduit based on the determined pressure.

A coupler cylinder is driven between a locked state and an unlocked state of a bucket by being supplied with hydraulic oil. A main pump supplies the hydraulic oil to the coupler cylinder. A pressure increasing valve controls the supply of the hydraulic oil to the coupler cylinder. A controller controls drive of the pressure increasing valve. The controller instructs the pressure increasing valve to stop the supply of the hydraulic oil to the coupler cylinder based on pressure in an oil passage between the main pump and the coupler cylinder.

A pilot hydraulic system may include a pilot pressure source, a pilot pressure return tank, a pilot valve, a pilot pressure supply line connecting the pilot pressure source to the pilot valve, and a pilot pressure return line connecting the pilot pressure return tank to the pilot valve. A main control valve may include a pilot chamber. A pilot pressure control line connects the pilot valve to the pilot chamber. A hydraulic sub-system is provided for modifying pilot pressure provided to the pilot chamber of the main control valve. The hydraulic sub-system may include a variable orifice valve disposed in the pilot pressure control line, a pilot pressure bypass line communicating the pilot pressure control line downstream of the variable orifice valve with the pilot pressure return line, and an electrohydraulic pressure reducing valve (EHPRV) disposed in the pilot pressure bypass line.

The present invention pertains to an air cylinder (10) in which flow rate controllers (24, 24A) are built into a head cover (14) and a rod cover (16), said flow rate controllers (24, 24A) being provided with a first flow rate adjustment part (28) connected between a port (14a, 16a) and a cylinder chamber (12c), a second flow rate adjustment part (32) provided adjacent to the first flow rate adjustment part (28), and a pilot check valve (38) connected in series to the second flow rate adjustment part (32). In response to the pressure of pilot air, the pilot check valve (38) switches between a state in which the passage of exhaust air from the cylinder chamber (12c) is permitted and a state in which the passage of exhaust air is prevented.