A hydraulic system for a vehicle includes a first hydraulic pump including a first displacement actuator and a first pressure port, a first load sense system fluidly coupled to the first displacement actuator, a second hydraulic pump including a second displacement actuator and a second pressure port, a second load sense system fluidly coupled to the second displacement actuator, and a crossover pressure controller coupled between the first pressure port and the second pressure port. The crossover pressure controller reconfigurable between (a) a combined pressure configuration providing fluid communication between the first pressure port and the second pressure port and (b) a separate pressure configuration inhibiting fluid communication between the first pressure port and the second pressure port. The crossover pressure controller is actuatable independent of the first load sense system and the second load sense system.

A hydraulic drive for executing a linear movement includes a motor, a pump, a lifting cylinder having the one linearly movable piston and a cylinder housing with at least one first connection and at least one second connection, a spring arranged such that the piston can be extended or retracted when the spring is in the relaxed state, and at least one first valve with which the first connection and the second connection of the cylinder housing can be fluidly connected. At least one second valve connected in parallel with the first valve is further provided, wherein the first valve has a maximum volumetric throughflow which is greater than the maximum volumetric through-flow of the second valve.

The invention relates to a pressure-limiting device designed to be installed in a system comprising a first line (11) and a second line (12) that can comprise pressurised oil, as well as comprising a discharge and/or booster line (10). The device also comprises a pressure selector (130, 150) in the form of a cage defining two seats (132, 134) and two pressure relief valves (160, 180). The limiting device is characterised in that it further comprises at least one means (170, 172; 190, 192) for regulating a pressure relief valve, disposed on the outside of an axial end of the pressure selector (150), in the form of a cage that allows the loading of the associated pressure relief valve to be regulated.

A machine comprises a frame, a plurality of ground engaging units, a plurality of moveable legs, and a hydraulic system. A first ground engaging unit and a second ground engaging unit connect a first leg and a second leg, respectively, with the frame. The hydraulic system controls heights of the plurality of moveable legs. The hydraulic system comprises a fluid circuit to control fluid between the first and second legs, a load holding valve to control fluid flow into the fluid circuit, and first and second relief valves to control flow of fluid between the first and second legs in opposite directions. A method for controlling slope of a construction machine comprises activating a relief valve connecting right and left lifting cylinders to control flow of hydraulic fluid between the lifting cylinders to control retraction of one of the lifting cylinders from retracting.

A hydraulic cooler pressure isolation circuit for a header of an agricultural harvester equipped with a reservoir and a pump. The circuit comprises a hydraulic fluid cooler, a supply line extending from the hydraulic fluid cooler to the pump, a return line extending from the hydraulic fluid cooler to the reservoir, and a drain line operatively in fluid communication with the return line for connecting to the reservoir. A first valve, a second valve, a return valve, and a bypass valve of the circuit operate to direct hydraulic fluid flow through the cooler under normal system operating conditions, and direct hydraulic fluid flow to bypass the cooler when the system experiences high pressure operating conditions at the cooler.

A working machine includes a prime mover, a hydraulic pump driven by power of the prime mover, a cooler including a cooling fan rotated by either the power of the prime mover or hydraulic fluid delivered from the hydraulic pump, and a controller configured or programmed to perform a reduction control for reducing a target fan rotation speed that is a target rotation speed of the cooling fan in response to reduction of an actual prime mover rotation speed that is an actual rotation speed of the prime mover, and to perform, after the reduction control, a restoration control for restoring the target fan rotation speed. The controller is configured or programmed to make a difference between a reduction rate of the target fan rotation speed in the reduction control and an increase rate of the target fan rotation speed in the restoration control.

A system for controlling a variable valve apparatus may include a plurality of oil control valves (OCVs) configured to respectively supply oil from an oil pump to a plurality of variable valve apparatuses or block the supply of the oil, and a single relief valve coupled to the plurality of oil control valves, wherein pressure in a plurality of control galleries for providing an oil supply path from the plurality of oil control valves to the plurality of variable valve apparatuses is maintained constant by only the single relief valve.

A system for controlling a variable valve apparatus may include a plurality of oil control valves (OCVs) configured to respectively supply oil from an oil pump to a plurality of variable valve apparatuses or block the supply of the oil, and a single relief valve coupled to the plurality of oil control valves, wherein pressure in a plurality of control galleries for providing an oil supply path from the plurality of oil control valves to the plurality of variable valve apparatuses is maintained constant by only the single relief valve.

The present disclosure relates to a closed circuit hydraulic system for a construction machine including a plurality of actuators and a plurality of hydraulic pumps selectively supplying working oil to the plurality of actuators bidirectionally and the closed circuit hydraulic system includes: a charge line selectively connected with a low-pressure side hydraulic line which returns to the hydraulic pump from the actuator among hydraulic lines connecting the hydraulic pumps and the actuators; a charge pump supplying a supplement flow to the charge line; and a variable relief valve selectively changing a normal mode to limit a pressure of the charge line to a predetermined pressure or less and a boost mode to limit the pressure of the charge line to a pressure lower than the pressure of the charge line in the normal mode.

A hydraulic system for a vehicle includes a first hydraulic pump including a first displacement actuator and a first pressure port, a first load sense system fluidly coupled to the first displacement actuator, a second hydraulic pump including a second displacement actuator and a second pressure port, a second load sense system fluidly coupled to the second displacement actuator, and a crossover pressure controller coupled between the first pressure port and the second pressure port. The crossover pressure controller reconfigurable between (a) a combined pressure configuration providing fluid communication between the first pressure port and the second pressure port and (b) a separate pressure configuration inhibiting fluid communication between the first pressure port and the second pressure port. The crossover pressure controller is actuatable independent of the first load sense system and the second load sense system.