There are provided a bar-shaped piston rod having one end portion attached to a marine vessel propulsion machine main body; an inner cylinder; an inner piston mounted in the other end portion of the piston rod, is accommodated in the inner cylinder, and divides a space in the inner cylinder into a fourth chamber on the one end portion side and a fifth chamber on the other end portion side; an outer cylinder accommodating the inner cylinder therein; and an outer piston covering an opening portion of one end portion of the inner cylinder in a state where the piston rod is exposed, divides a space in the outer cylinder into a second chamber on one end portion side and a first chamber on the other end portion side, and is formed with a through hole that allows the fourth chamber and the second chamber to communicate with each other.

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 structure, an upper swing structure swingably mounted on the lower traveling structure, an engine mounted on the upper swing structure, a hydraulic pump configured to be driven by the engine, and processing circuitry configured to determine a command value by energy saving control and to control a flow rate of hydraulic oil discharged by the hydraulic pump according to the command value. The processing circuitry is configured to control the command value.

Disclosure herein are hydraulic systems and method of use thereof. The hydraulic systems can include a hydraulic cylinder and a manifold. The hydraulic cylinder can have a first end and a second end. The hydraulic cylinder can include a first port, a second port, and a third port. The first port can be located proximate the first end. The second port cane be located proximate the second end. The third port can be located in between the first port and the second port. The manifold can include a first valve and a second valve. The first valve can be in fluid communication with the first port and the third port. The second valve can be in fluid communication with the second port and the third port.

A flow controller that changes the flow rate of air exhausted from an air cylinder in mid-stroke includes a first switching valve displaced from a first position to a second position under the effect of pilot air, and causing one port of the air cylinder to communicate with a first channel at the first position, exhausting air exhausted from the one port of the air cylinder while reducing the flow rate of the air using a first regulating valve at the second position. Since the pilot air is taken into the first switching valve from a second channel in a system different from the system of the first channel, a second regulating valve can be adjusted without being affected by the degree of opening of the first regulating valve.

Provided is a driving apparatus capable of effectively preventing impact at the stroke end in the hydraulic cylinder. The driving apparatus includes a hydraulic pump, a cylinder control valve, an operation member, a drive command input unit inputting a cylinder drive command corresponding to a cylinder operation applied to the operation member to the cylinder control valve, a cylinder stroke detection unit, a cylinder drive command restriction unit restricting the cylinder drive command in response to the cylinder stroke to stop a piston of a hydraulic cylinder before the stroke end.

Provided is a driving apparatus capable of effectively preventing impact at the stroke end in the hydraulic cylinder. The driving apparatus includes a hydraulic pump, a cylinder control valve, an operation member, a drive command input unit inputting a cylinder drive command corresponding to a cylinder operation applied to the operation member to the cylinder control valve, a cylinder stroke detection unit, a cylinder drive command restriction unit restricting the cylinder drive command in response to the cylinder stroke to stop a piston of a hydraulic cylinder before the stroke end.

An accumulator includes: a main cylindrical housing having a closed first axial end and a second axial end; a piston arranged in the main cylindrical housing and sealed to an inner surface of the main cylindrical housing, which piston is movable in an axial direction and provides with the main cylindrical housing and the closed first axial end of the main cylindrical housing a variable accumulating space; an urging device arranged between the piston and the second axial end of the main cylindrical housing for urging the piston towards the first axial end of the main cylindrical housing; a fluid supply opening arranged in the first axial end of the main cylindrical housing, which fluid supply opening is in fluid connection with the variable accumulating space; and a protective cylindrical housing having a first and a second axial end, the protective cylindrical housing being arranged concentrically.

A balancing valve includes four ports. While the pressures at a pair of balancing ports of a hydraulic balancing valve are equal, the valve maintains two other ports in a closed position. Upon a pressure differential between the balancing ports, fluid communication can occur between one of the balancing ports and either of the other ports based upon the direction of the pressure differential. A hydraulic ride control system utilizes the balancing valve together with other control valves to provide ride control functionality.

A control method for executing a floating function of a boom in a work vehicle includes determining that a predetermined floating function activation command has been inputted by the operator by means of a command input means. When the floating function activation command has been inputted by the operator, acquiring, a signal or data indicative of the current position of the boom along a travel path of the boom over time, the travel path including a first section between a boom full extension position and a deceleration position, a second section between the deceleration position and a grounding position, and a third section between the grounding position and a full retract position, and moving the boom from the current position, determined based on the signal or data indicative of the position of the boom, to the full retract position.