In one aspect, a system for controlling an operation of an actuator mounted on a seed planting implement may include an actuator configured to adjust a position of a row unit of the seed planting implement relative to a toolbar of the seed planting implement. The system may also include a flow restrictor fluidly coupled to a fluid chamber of the actuator, with the flow restrictor being configured to reduce a rate at which fluid is permitted to exit the fluid chamber in a manner that provides damping to the row unit. Furthermore, the system may include a valve fluidly coupled to the flow restrictor in a parallel relationship such that the valve is configured to permit the fluid exiting the fluid chamber to flow through the flow restrictor and the fluid entering the fluid chamber to bypass the flow restrictor.

The invention provides a hydraulic circuit for feeding an actuator (1) comprising first and second chambers (5, 6), the circuit comprising a slide valve (10) with a slide (16) that is movable between first and second extreme positions (18, 19) on either side of a stable central position (17) so that: in the central position, it connects the chambers (5, 6) of the actuator to a return port; in the first extreme position (18), it connects the first chamber (5) to a feed port and the second chamber to the return port; and in the second extreme position (19), it connects at least the second chamber (6) to the feed port.

According to the invention, the hydraulic circuit includes pressure-maintaining means (20) for maintaining pressure in the first chamber of the actuator while the slide is passing through the central position on being moved from the first extreme position to the second extreme position.

A hydraulic energy regeneration system for a work machine for boosting a pressure of a return hydraulic fluid of a hydraulic cylinder and regenerating the hydraulic fluid, prevents a bottom pressure from reaching an overload relief set pressure and suppresses a changeover shock to ensure favorable operability. The hydraulic energy regeneration system for the work machine, includes: a communication pressure boost passage that can boost a pressure of a discharge-side hydraulic fluid by communicating a discharge side and a suction side of the hydraulic cylinder with each other during an own weight fall of a driven body; a communication pressure boost valve that is disposed in the communication pressure boost passage and that can regulate one of or both of a pressure and a flow rate of the communication pressure boost passage; a reuse-side line and a reuse control valve or a regeneration-side line and a regeneration control valve that can regenerate a hydraulic fluid discharged from the hydraulic cylinder during the own weight fall of the driven body; and a controller. The controller is configured to reduce an opening degree of the communication pressure boost valve in response to an increase of the discharge-side pressure of the hydraulic cylinder right after the discharge-side pressure reaches a preset high load set pressure, and gradually reduces the opening degree of the communication pressure boost valve with passage of time.

A speed controller is capable of being applied to a cylinder with a short stroke with a simple structure. The speed controller includes a first flow channel and a second flow channel allowing a first port and a second port to communicate with each other, into which pressure fluid is allowed to flow, in which a first valve is arranged in the first flow channel, a second valve is arranged in the second flow channel, a third flow channel and a fourth flow channel are further included, and a third valve is arranged in the third flow channel, allowing only flowing from the first port toward a portion on the piston shaft side with respect to a piston in a cylinder chamber in the third flow channel as well as closing the first flow channel and the fourth flow channel by moving a third valve body in a direction of opening the third flow channel, and opening the first flow channel and the fourth flow channel by moving the third valve body in a direction of closing the third flow channel.

A boom cylinder drives a boom, and includes a head side oil chamber and a bottom side oil chamber. A first valve includes a first opening for discharging oil in the head side oil chamber to an oil tank, and supplies oil from a hydraulic pump to the head side oil chamber. A second valve includes a second opening for discharging oil in the bottom side oil chamber to the oil tank, and supplies oil from the hydraulic pump to the bottom side oil chamber. A controller individually controls an opening degree of the first opening and an opening degree of the second opening, during work including manipulation of the boom.

In a cylinder drive device, a throttle valve and a second check valve are provided between a switch valve and a first cylinder chamber of a fluid pressure cylinder. The cylinder drive device has a flow channel unit which is interposed between a manifold and the switch valve, which allows communication between the throttle valve and the second check valve and switch valve, and which communicates with a plurality of holes in the manifold to allow a fluid to flow to the switch valve.

A tilting system for a suspended cab of a work vehicle includes a hydraulic cylinder coupled to a chassis of the work vehicle at a first end and the suspended cab at a second end. Further, the hydraulic cylinder is configured to extend to drive the suspended cab to rotate from a lowered position to a raised position. In addition, the hydraulic cylinder is configured to be substantially horizontal while the suspended cab is in the lowered position.

A valve system for use with a cylinder having an extensible rod, includes a first valve assembly including a first inlet/outlet port, a check valve biased toward a closed state, the check valve having a check valve body at least partially receivable within a first port of the cylinder, a flow control valve positioned in series between the first inlet/outlet port and the check valve, and a first pilot port selectively communicable with a pressurized gas for opening the check valve. The valve system further includes a second valve assembly including a second inlet/outlet port, a second pilot port through which the pressurized gas must flow before being introduced to the first pilot port, and a valve body at least partially receivable within a second port of the cylinder, wherein the second inlet/outlet port and the second pilot port are integrally formed as a portion of the valve body.

When a tilt in a right-and-left direction occurs in a cargo bed (9) being raised due to imbalance of excavated materials, the tilt is detected as a roll angle (?R), and it is determined whether the absolute value (|?R|) of the roll angle is not less than an imbalance determination value (?2) (S4). When the absolute value is not less than the imbalance determination value (?2) (Yes in S4) and the roll angle (?R) is positive (the cargo bed (9) is rising to the right) (Yes in S8), an oil supply amount (VL) to a hoist cylinder (11) on the left side is increased, and an oil supply amount (VR) to a hoist cylinder (12) on the right side is decreased (S9). When the roll angle (?R) is negative (the cargo bed (9) is rising to the left) (No in S8), the oil supply amount (VL) on the left side is decreased, and the oil supply amount (VR) on the right side is increased (S10).

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.