A work machine, preferably a mobile work machine, has an attachment device, in particular a trench cutter. The attachment device has at least two adjustable hydraulic motors for driving independent, individually controllable loads. The hydraulic supply of the adjustable hydraulic motors takes place by a hydraulic drive unit arranged externally from the attachment device, in particular by a drive unit of the work machine. The at least two adjustable hydraulic motors of the attachment device are connected to a constant pressure network provided by the hydraulic drive unit.

A transport vehicle is driven by a hydraulic closed circuit system having a variable displacement pump to send an operating fluid to a delivery branch and receive the operating fluid from a return branch, a plurality of hydraulic motors connected to the delivery branch and to the return branch in order to drive relative wheels of the vehicle, a command and control unit to control the pump and the hydraulic motors in an ordinary advancing condition of the vehicle and command and control unit, which is configured to intervene in case of faults or malfunctions of the pump and to control a valve so as to establish a connection between the delivery branch and the return branch regardless of the control of the command and control unit of the pump and of the hydraulic motors.

A transport vehicle is driven by a hydraulic closed circuit system having a variable displacement pump to send an operating fluid to a delivery branch and receive the operating fluid from a return branch, a plurality of hydraulic motors connected to the delivery branch and to the return branch in order to drive relative wheels of the vehicle, a command and control unit to control the pump and the hydraulic motors in an ordinary advancing condition of the vehicle and command and control unit, which is configured to intervene in case of faults or malfunctions of the pump and to control a valve so as to establish a connection between the delivery branch and the return branch regardless of the control of the command and control unit of the pump and of the hydraulic motors.

A working machine includes a prime mover, a traveling pump driven by a power of the prime mover to deliver operation fluid, a traveling motor rotated by the operation fluid delivered from the traveling pump to have a rotation speed stage shiftable between a first speed stage and a second speed stage higher than the first speed stage, a traveling switching valve shiftable between a first state where the rotation speed stage of the traveling motor is set to the first speed stage and a second state where the rotation speed stage of the traveling motor is set to the second speed stage, an actuation valve configured to change a pilot pressure of a pilot fluid to control a flow of operation fluid delivered from the traveling pump, and a controller configured to control the pilot pressure of the pilot fluid output from the actuation valve so that a value of the pilot pressure differs depending on whether the set rotation speed stage of the traveling motor is the first speed stage or the second speed stage.

A hydraulic system for a work vehicle includes a hydraulic motor configured to generate rotational power for one or more wheels on the work vehicle. The hydraulic system also includes a hydraulic pump coupled to the hydraulic motor, wherein the hydraulic pump is configured to pump hydraulic fluid to the hydraulic motor. The hydraulic control system includes a processor that is configured to receive an input indicative of a selection of a number of speed ranges that span between a minimum speed and a maximum speed for the work vehicle and to provide a motor command to set a motor volume of the hydraulic motor and a pump command to set a limit for a pump volume of the hydraulic pump to enable the number of speed ranges for the work vehicle.

A working machine includes a machine body, a prime mover, a traveling device mounted on the machine body, a traveling motor to provide a power to the traveling device and to switch between a first speed and a second speed higher than the first speed, a traveling pump to be driven by the prime mover and to supply operation fluid to the traveling motor, and a controller device including an automatic shifter to automatically shift the traveling motor to the first speed or to the second speed, a timer to count an elapsed time from the automatically shifting, and a shift prohibitor to prohibit the automatically shifting by the automatic shifter when the elapsed time counted by the timer is less than a threshold.

A utility vehicle such as a loader includes a drive control system that includes an electronic controller and a manually actuated drive command device, such as one or more joysticks. The electronic controller is configured to control the drive control system to supply propulsive power at a predetermined output that is lower than that which is commanded by the drive command device for so long as an output of the drive control system is beneath a designated threshold, maintaining vehicle speed lower than a commanded vehicle speed. The electronic controller is further configured to control the drive control system to ramp up the propulsive power supply toward that which is commanded by the drive command device when the output of the drive control system is above the designated threshold, causing the vehicle speed to approach a commanded vehicle speed. The vehicle may include a EH drive system such as a hydrostatic drive system.

A hydraulic system for a work machine includes a tank to store an operation fluid, a hydraulic device to be operated by the operation fluid, a control valve to control the hydraulic device, a first fluid tube connecting the hydraulic device and the control valve, the first fluid tube being to supply the operation fluid from the control valve to the hydraulic device, a second fluid tube branching from the first fluid tube and connected to the tank, a switch valve provided to the second fluid tube, the switch valve being to control a flow rate of the operation fluid, and an oil cooler provided to the second fluid tube between the switch valve and the tank.

A working machine includes a traveling device to change a traveling speed in accordance with a flow rate of an operation fluid, a traveling operation device to change the flow rate of the operation fluid to be supplied to the traveling device, and a switching operation portion to change, at multiple steps, a supply amount of the operation fluid to be supplied to the traveling device, the supply amount corresponding to an operation extent of the traveling operation device.

A system for controlling an operation of a hydrostatic circuit of a work machine includes a flush control valve. The flush control valve is configured to be fluidly coupled to the hydrostatic circuit. The hydrostatic circuit is configured to operate in at least two operating modes to supply fluid power to selectively run a plurality of sub-systems of the work machine. In at least one operating mode of the at least two operating modes of the hydrostatic circuit, the flush control valve is configured to move and regulate a flushing flow rate of the fluid to equalize the flushing flow rate with a desired flushing flow rate based on a signal indicative of the at least one operating mode.