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 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 fluid leakage detection system has a detection space to which working oil leaked out through a rod seal is guided; the rod seal being configured to seal an annular gap between a piston rod and a cylinder head; a sensor unit configured to detect pressure in the detection space; and a controller configured to acquire detected result from the sensor unit, wherein the controller has: a calculation unit configured to calculate a pressure parameter representing a pressure fluctuation in the detection space; a determination unit configured to determine occurrence of leakage of the working oil based on the pressure parameter; and the pressure parameter includes an upper limit value and a lower limit value of the pressure fluctuation obtained from the detected result detected by the sensor unit within a predetermined detection period.

A single solenoid-controlled electro-hydraulic liftomatic system is provided. The single solenoid-controlled electro-hydraulic liftomatic system is developed for controlling electrically, automating a hydraulic mechanism used in three-point hitch systems of tractors lifted and lowered by a mechanically controlled hydraulic mechanism. The single solenoid-controlled electro-hydraulic liftomatic system includes an actuator, a hydraulic pump, a safety element, a tank line, a valve body, a hydraulic piston, at least one solenoid valve, a piston spring, a check valve, a time-delay relay, and a button.

A hydraulic circuit includes a hydraulic power unit, a first cylinder pair coupled with the hydraulic power unit, and a second cylinder pair coupled with the hydraulic power unit in parallel with the first cylinder pair. Re-phasing valves coupled with each cylinder of the first and second cylinder pairs are activated when a respective one of the cylinders reaches one of a fully extended or a fully retracted position. The hydraulic circuit incorporates the serially plumbed, re-phasing cylinders for synchronized movement in a system with multiple pairs of cylinders.

A power control system for a forestry machine may include an engine control module and a pump control module. The engine control module may be configured to control an engine speed of an engine of the forestry machine. The engine speed may be limited in accordance with a maximum engine speed. The pump control module may determine whether a first function of the forestry machine is activated, determine whether a sensed pressure of a pump associated with the first function is greater than or equal to a high pressure setpoint, and output a control signal indicating a request for a power increase in response to determining that the first function is activated and the sensed pressure is greater than or equal to the high pressure setpoint. The engine control module may increase the maximum engine speed in response to the request for the power increase from the pump control module.

The present invention provides a controller for a hydraulic apparatus. The controller is configured to determine (410) that a mode change criteria has been met for the hydraulic apparatus. In response to the determination, the controller is configured to control (420) a valve arrangement to change a first actuator chamber of a hydraulic actuator between being fluidly connected to a hydraulic machine and fluidly isolated from a second chamber of the hydraulic actuator, and being fluidly connected to both the second actuator chamber and the hydraulic machine. Further in response to the determination, the controller is configured to control (430) the hydraulic machine to change a flow rate of hydraulic fluid flowing through the hydraulic machine to regulate a movement of the hydraulic actuator during the control of the valve arrangement.

A fail-safe actuation system comprising an actuator having first and second chambers, a working circuit with a motor/pump device configured to actuate the actuator in an operative state, and a safety circuit configured to move the actuator into the safety position in a failure state, the safety circuit having a tank that holds pressurized fluid and that, in the failure state, is automatically connected to the first chamber via a switching valve, and having a drain valve that, in the failure state, is moved into a through-flow position in order to drain fluid out of the second chamber, the safety circuit configured such that, in the operative state, an inflow into the actuator—in a manner that is decoupled from the tank—is established by the working circuit, and, in the failure state, an inflow from the tank into the first chamber—in a manner that is completely decoupled from the working circuit—is created by the safety circuit, whereby a short-circuit fluid connection is provided between the first and second chambers that, in the failure state, is through-connected in order to generate a short-circuit flow between the first and second chambers.

A working vehicle provided with a fixed-capacity hydraulic pump driven by power from an engine and a working hydraulic actuator driven by working oil pumped from the fixed-capacity hydraulic pump is a rotary working vehicle which is provided with an electromagnetic relief valve for modifying the pressure of working oil from the fixed-capacity hydraulic pump, and the rotary working vehicle is such that if the actual number of revolutions (N) of the engine is reduced by a set number of revolutions (Ns) as the load on the engine increases, then the electromagnetic relief valve operates in accordance with the deviation (e) between the actual number of revolutions (N) of the engine and the specified number of revolutions (Ns), and the pressure of the working oil from the fixed-capacity hydraulic pump is modified.

A dump trailer and a hydraulic cylinder assembly for the dump trailer are described herein. The cylinder assembly includes a first barrel, a second barrel rigidly coupled to the first barrel along a longitudinal axis of the cylinder assembly, and a piston assembly. The first barrel includes an inlet port for receiving vehicle hydraulic fluid and an outlet port for providing the vehicle hydraulic fluid to the vehicle. The second barrel includes an inlet port and an outlet port for providing dump trailer hydraulic fluid to a hydraulic lifting mechanism of the dump trailer. The piston assembly includes a first piston and a second piston coupled to the first piston by a shaft. The piston assembly is configured to provide the dump trailer hydraulic fluid to the hydraulic lifting mechanism to lift a box of the dump trailer when the cylinder assembly receives hydraulic fluid from the vehicle.