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.

The controller determines whether the vehicle is in a shuttle motion from the operating position of the forward/reverse travel operating member and the actual traveling direction of the vehicle. The controller determines a target braking force when the vehicle is in the shuttle motion. The controller determines at least one of a target displacement of the travel pump and a target displacement of the travel motor based on the target braking force.

Methods and systems for transmission control are provided. In one example, a transmission system operating method includes maintaining a displacement set-point of a variable displacement hydraulic motor in a hydrostatic assembly within a working zone, where at least a portion of a boundary of the working zone is determined based on a torque constraint of the hydrostatic assembly. The transmission system includes the hydrostatic assembly that includes the hydraulic motor that is hydraulically coupled in parallel with a variable displacement hydraulic pump and a gearbox mechanically coupled to the hydrostatic assembly and including one or more clutches.

Methods and systems for transmission control are provided. In one example, a transmission system operating method includes maintaining a displacement set-point of a variable displacement hydraulic motor in a hydrostatic assembly within a working zone, where at least a portion of a boundary of the working zone is determined based on a torque constraint of the hydrostatic assembly. The transmission system includes the hydrostatic assembly that includes the hydraulic motor that is hydraulically coupled in parallel with a variable displacement hydraulic pump and a gearbox mechanically coupled to the hydrostatic assembly and including one or more clutches.

A hydraulic system for a working machine includes a traveling motor to output power to a traveling device in the working machine, a first detector to detect a physical quantity that changes in accordance with a traveling state of the working machine and that is detected at intervals of a predetermined period, and a controller to execute automatic shift-down to automatically reduce a rotational speed of the traveling motor to a first speed stage when the rotational speed of the traveling motor is in a second speed stage higher than the first speed stage. The controller is configured or programmed to determine a tendency or degree of change in the physical quantity, based on values of the physical quantity detected at intervals of the predetermined period by the first detector.

A hydraulic system for a working machine includes a traveling motor to output power to a traveling device in the working machine, a first detector to detect a physical quantity that changes in accordance with a traveling state of the working machine and that is detected at intervals of a predetermined period, and a controller to execute automatic shift-down to automatically reduce a rotational speed of the traveling motor to a first speed stage when the rotational speed of the traveling motor is in a second speed stage higher than the first speed stage. The controller is configured or programmed to determine a tendency or degree of change in the physical quantity, based on values of the physical quantity detected at intervals of the predetermined period by the first detector.

A drum drive system includes a controller configured to selectively control an engine, a variable displacement pump, and a variable displacement motor of a vehicle to provide a target drum speed for a drum of the vehicle. To provide the target drum speed, the controller is configured to: (i) initially operate the variable displacement motor at a maximum motor displacement and operate the variable displacement pump at a pump displacement that provides the target drum speed without needing to actively manipulate an engine speed of the engine; (ii) increase the pump displacement and decrease a motor displacement without needing to actively manipulate the engine speed while still providing the target drum speed; and (iii) increase the engine speed in response to the pump displacement reaching a maximum pump displacement and the motor displacement reaching a minimum motor displacement if necessary to maintain the target drum speed.

The invention relates to a self-propelled construction machine, in particular a road milling machine, stabiliser, recycler or surface miner, which has a machine frame 2 supported by at least three running gears 10A, 10B, 11A, 11B, a drive device 14 for driving at least two running gears, and a work roller 4 arranged on the machine frame. The invention also relates to a method for controlling a construction machine of this kind. The drive device 14 comprises adjustable hydraulic motors 15, 16, 17, 18 associated with the drivable running gears, which hydraulic motors have a displacement volume Vg that can be varied by an adjusting device 15A, 16A, 17A, 18A, and comprises at least one adjustable travel drive—hydraulic pump 19 driven by at least one drive motor to supply the hydraulic motors with a variable total volume flow Q of hydraulic fluid. In addition, a controller 28 is provided which is configured in such a way that a partial volume flow Q.sub.1, Q.sub.2, Q.sub.3, Q.sub.4 is determined for each adjustable hydraulic motor 15, 16, 17, 18 from the total volume flow Q provided by the at least one travel drive—hydraulic pump 19, by means of which partial volume flow the particular hydraulic motor is to be operated, and when the speed n of an adjustable hydraulic motor increases as a result of slippage of the running gear associated with the adjustable hydraulic motor, the adjusting device of the adjustable hydraulic motor is controlled in such a way that a displacement volume Vg is set for the adjustable hydraulic motor, at which displacement volume the partial volume flow determined for the adjustable hydraulic motor is maintained. The self-propelled construction machine according to the invention is characterised in that a hydraulic flow divider is not required.

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 provided thereon with a traveling pump and a traveling motor; a traveling change-over valve shiftable between a first state where a rotation speed of the traveling motor is set to a first speed and a second state where the rotation speed is set to a second speed; an actuation valve operable to control a flow of operation fluid to an operation valve that changes a pressure of operation fluid to be applied to the traveling pump according to operation of an operation member; and a controller to perform a shock-mitigation control for reducing an opening degree of the actuation valve when the traveling change-over valve is shifted from the first state to the second state. The controller determines a reduction amount of the opening degree of the actuation valve reduced by the shock-mitigation control, based on a straight-traveling degree of the machine body.