An actuator system includes a piston-cylinder arrangement including a piston that is movable with respect to a cylinder. A first flow path is in fluid communication with the piston-cylinder arrangement and a second flow path is in fluid communication with the piston-cylinder arrangement. A control system is operable to fluidly connect the first flow path to a source of high-pressure fluid and to connect the second flow path to a drain to move the piston in a first direction. A pressure sensor is fluidly connected to the first flow path and is operable to measure sufficient pressure data during the movement of the piston to generate a pressure versus time curve. The control system is operable to compare the generated pressure versus time curve to a known standard pressure versus time curve stored in the control system to determine the condition of the piston-cylinder arrangement.

In one embodiment, an agricultural implement system includes a row unit, the row unit configured to dispose seed into a ground trench, and closing system corresponding to the row unit, the closing system configured to close the ground trench after disposition of the seed. The agricultural implement system further includes a double acting cylinder mechanically coupled to the closing system, the double acting cylinder comprising a cylinder side port and a rod side port and a fluid source fluidly coupled to the cylinder side port and configured to provide a cylinder side fluid. The agricultural implement system additionally includes a filter fluidly coupled to the rod side port. Filtered fluid enters the double acting cylinder via the rod side port.

A hydraulic system for a working machine includes a first electric machine connected to a first hydraulic machine; a second electric machine connected to a second hydraulic machine, an output side of the second hydraulic machine being connected to an input side of the first hydraulic machine; at least one hydraulic consumer hydraulically coupled to an output side of the first hydraulic machine via a supply line and configured to be powered by the first hydraulic machine; and a valve arrangement arranged between the hydraulic consumer and the first and second hydraulic machines, wherein the valve arrangement is configured to control a return flow of hydraulic fluid from the hydraulic consumer to either the input side of the first hydraulic machine or an input side of the second hydraulic machine based on a requested output pressure from the first hydraulic machine.

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 rotating head assembly includes a body, an implement, a clamp assembly, a drive member, a hydraulic motor, and a bypass circuit. The drive member is threadingly connected to a first clamp member and a second clamp member. The hydraulic motor is connected to the drive member to cause the drive member to rotate in a selected direction. An inlet of the bypass circuit is in fluid communication with an inlet of the hydraulic motor to receive a portion of the pressurized hydraulic fluid passing to the hydraulic motor. An outlet of the bypass circuit is in fluid communication with the outlet of the hydraulic motor. At least one bypass valve is interposed between the inlet of the bypass circuit and the outlet of the bypass circuit. The bypass valve has an actuator positioned adjacent one of the first clamp member and the second clamp.

A hydraulic circuit includes a pump connected to a tank for supplying hydraulic liquid under pressure to a component via a directional control slide valve provided with a feed port connected to an inlet of the component and with a return port connected to an outlet of the component. The hydraulic circuit further includes a pressure limiter connected to the inlet of the component and the tank, and a feed control system for the hydraulic component including a pressure sensor installed upstream of the hydraulic component downstream of the feed port for supplying information about the pressure of the hydraulic liquid and a setpoint pressure. The feed control system further including an actuator for controlling the movement of the directional control slide valve, and a control unit for generating a control signal for the actuator based on information about the pressure measured at the feed port.

A piston (8) is provided in a motor main body (4). A first motor chamber (9) is provided above the piston (8) and a second motor chamber (10) is provided below the piston (8). A pilot valve element (18) is provided so as to protrude from the piston (8). When a supply/discharge valve (13) is moved to its upper limit position or its lower limit position by the movement of the pilot valve element (18) in an up-down direction, a first valve member (25) of the supply/discharge valve (13) switches between supplying and discharging pressure fluid to and from the first motor chamber (9) and a second valve member (26) of the supply/discharge w valve (13) switches between supplying and discharging pressure fluid to and from the second motor chamber (10).

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 construction machine including a variable displacement pump, and a boom cylinder including a rod operable to extend and retract to move a boom of the construction machine. A first chamber of the boom cylinder is configured to be supplied with fluid from the pump during rod extension while fluid is removed from a second chamber of the boom cylinder. The second chamber of the boom cylinder is configured to be supplied with fluid from the pump during rod retraction while fluid is removed from the first chamber of the boom cylinder. The construction machine has an active ride control mode in which a valve between the boom cylinder and the pump remains open, and the pump is configured to actively damp pressure fluctuations in the boom cylinder by variation of a displacement setting.

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.