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.

An example valve includes: a valve body defining a bore, an inlet port, an outlet port, and a signal cavity; a spool movable in the bore to shift between a first position and an intermediate position, where the spool has a first end and a second end, where the outlet port is fluidly connected to the second end, where the valve body defines a spring cavity adjacent the first end of the spool to house a spring, where the first end is subjected to a load-sense pressure signal, and where when the spool is in the first position, the spool disconnects the inlet port from the outlet port and connects the inlet port to the signal cavity; and a valve actuator that, when activated, connects the signal cavity to the second end of the spool to move the spool in the bore from the first position to the intermediate position.

A hydraulic system including a first cylinder conduit configured to couple to a cylinder, an auxiliary conduit configured to couple to a case drain conduit, and a pressure regulator coupled to the first cylinder conduit and to the auxiliary conduit. The pressure regulator may block fluid flow to the auxiliary conduit if a first fluid pressure is less than or equal to a threshold pressure and enable fluid flow if the first fluid pressure is greater than the threshold pressure. The hydraulic system further includes a supplemental conduit with a check valve that directs fluid from the auxiliary conduit to a reservoir. The check valve blocks fluid flow if a second fluid pressure is less than or equal to a third fluid pressure, and enables fluid flow if the second fluid pressure greater than the third fluid pressure.

A valve body defines a work passage, a high-pressure channel fluidly connected to the work passage, a tank passage, and a cavity disposed between the high-pressure channel and the tank passage. The cavity fluidly connects the high-pressure channel and the tank passage. The cavity is defined at least in part by a first portion within which a relief valve threadedly engages, a second portion disposed adjacent to the high-pressure channel, and an annulus interposed between the first portion and the second portion. The annulus fluidly connects to the tank passage. A surface area of the relief valve exposed to the annulus is greater than a cross-sectional area of the high-pressure channel.

A hydraulic control system for linear actuation that provides a bypass flow during startup of a lifting command, provides a split flow between a cylinder and a reservoir once a minimum operating speed of a pump has been reached, and provides complete flow to a cylinder after the minimum operating speed of the pump has been reached. This is achieved through control of a flow control valve and a proportional flow control valve by a processor.

A pneumatic cylinder includes a cylinder body, a piston assembly, a connecting rod, and at least one pressure-relief valve. The cylinder body is formed with a cylinder chamber, and has an exterior disposed with at least one inlet-outlet passage and at least one pressure-relief opening, wherein the inlet-outlet passage is connected to the cylinder chamber. The piston assembly is contained within the cylinder chamber. The connecting rod is connected to the piston assembly, and protrudes out from the cylinder body. The pressure-relief valve is disposed in the pressure-relief opening, and has two ends connected to an outside of the pneumatic cylinder and the cylinder chamber respectively. When a gas pressure within the cylinder chamber is greater than a threshold value, the pressure-relief valve works to allow the cylinder chamber connecting to the outside for pressure relief.

A vehicle hydraulic control device for a rotating electrical machine and associated gear mechanism. Oil passages are configured with relief valves such that a first relief valve discharges oil in a first oil passage when an oil pressure in the first oil passage located downstream of a throttle portion becomes higher than a predetermined first set oil pressure, and a second relief valve allows a part of the second oil passage which is located upstream of the second relief valve to communicate with a part of the second oil passage which is located downstream of the second relief valve when an oil pressure in the second oil passage located upstream of the second relief valve becomes higher than a predetermined second set oil pressure set higher than the first set oil pressure.

A hydraulic system includes a hydraulic pump to output an operation fluid, first and second hydraulic devices to be operated by the operation fluid, first and second control valves to control the first and second hydraulic device, respectively, first and second communication tubes connecting the first hydraulic device to the first control valve, a supply fluid tube connecting the first control valve to the second control valve, the supply fluid tube being configured to supply the return fluid to the second control valve, first and second connection fluid tubes disposed on the first control valve, a discharge fluid tube connected to the first control valve, first and second branching fluid tubes branched from the first and second connection fluid tubes, respectively, first and second throttles disposed on the first and second branching fluid tubes, respectively, the second throttle being smaller than the first throttle.

To provide a construction machine that has a hydraulic system mounted thereon in which a closed-circuit pump, and an open-circuit pump and a proportional valve are arranged as a pair, and that makes it possible to use an unused open-circuit pump or proportional valve to accelerate the speed of a single rod hydraulic cylinder when the single rod hydraulic cylinder and a hydraulic motor are driven simultaneously. A controller (51) controls a cap-side selector valve (46) and a rod-side selector valve (47) such that a particular open-circuit pump (15) not connected to a single rod hydraulic cylinder (3) is connected to the single rod hydraulic cylinder, and controls an opening area of a particular proportional valve (49) provided on a flow line that connects a delivery port of the particular open-circuit pump to a tank, when the single rod hydraulic cylinder and a hydraulic motor (7) are driven simultaneously.

A flow control manifold apparatus includes a housing defining a first flow path from a flow input port to flow output port and a second flow path from a return inlet port to a return outlet port. A first flow regulating valve is placed inline the first flow path and an excess flow path fluidly couples the first flow path to the second flow path. An excess pressure valve is placed inline the excess flow path and is in a closed orientation when the first flow regulating valve is open so that all of the fluid exits through the flow output port. The excess pressure valve is then in a partially open orientation when the first flow regulating valve is partially closed so that a first portion of the fluid exits through the flow output port and a second portion of the fluid exits through the return outlet port.