Methods and systems for a hydromechanical transmission are provided herein. In one example, a vehicle system is provided that includes a hydromechanical transmission with a power-take off (PTO) that is designed to rotationally couple to an implement. The vehicle system further includes an engine coupled to the hydromechanical transmission and a power-management control unit configured to, during a drive or coast condition, cause the power-management control unit to: determine a net available power for the hydromechanical transmission and manage a power flow between the hydromechanical transmission, a drive axle, and the implement based on the net available power.

A method for driving a transmission mechanism output power in response to an anticipated fluid-pressure gradient field is provided. The method includes sensing the change of direction of pressure gradient field at a desired location from the different area of the transmission mechanism within fluid. The method further includes constructing fluid-pressure gradient field based upon isolation-fluid apparatus or low-density fluid space installed on a transmission mechanism within fluid.

A method for driving a transmission mechanism output power in response to an anticipated fluid-pressure gradient field is provided. The method includes sensing the change of direction of pressure gradient field at a desired location from the different area of the transmission mechanism within fluid. The method further includes constructing fluid-pressure gradient field based upon isolation-fluid apparatus or low-density fluid space installed on a transmission mechanism within fluid.

A method of managing operation of a machine is described herein. The machine includes drive components that supply a propulsive force exerted by the machine on a traveled surface. The machine includes a programmed controller that controls power output by a motor to the drive components of the machine, in accordance with a slippage model, to actively manage excessive slippage at a physical interface between the machine and the traveled surface. The programmed controller determines a track force indicative of the propulsive force exerted by the machine on the traveled surface. The programmed controller further determines a modeled slippage based, at least in part, upon the track force and the slippage model. The machine conditionally causes a reduction of the power output by the motor based upon a comparison, by the programmed controller, between the modeled slippage and a slippage limit.

A method of managing operation of a machine is described herein. The machine includes drive components that supply a propulsive force exerted by the machine on a traveled surface. The machine includes a programmed controller that controls power output by a motor to the drive components of the machine, in accordance with a slippage model, to actively manage excessive slippage at a physical interface between the machine and the traveled surface. The programmed controller determines a track force indicative of the propulsive force exerted by the machine on the traveled surface. The programmed controller further determines a modeled slippage based, at least in part, upon the track force and the slippage model. The machine conditionally causes a reduction of the power output by the motor based upon a comparison, by the programmed controller, between the modeled slippage and a slippage limit.

A power transmission device includes an input shaft, an output shaft, a differential device, a continuously variable transmission unit, and a control device. The differential device includes a first rotation element connected to the input shaft, a second rotation element connected to the output shaft, and a third rotation element. The continuously variable transmission unit includes a conversion unit configured to convert rotational power of the third rotation element into an other power, and a reconversion unit configured to reconvert the converted other power into the rotational power and supply the reconverted rotational power to the output shaft. The control device includes a continuously variable transmission control unit configured to generate a control signal of the continuously variable transmission unit such that the other power generated by the conversion unit exceeds the other power input to the reconversion unit.

A power transmission device includes an input shaft, an output shaft, a differential device, a continuously variable transmission unit, and a control device. The differential device includes a first rotation element connected to the input shaft, a second rotation element connected to the output shaft, and a third rotation element. The continuously variable transmission unit includes a conversion unit configured to convert rotational power of the third rotation element into an other power, and a reconversion unit configured to reconvert the converted other power into the rotational power and supply the reconverted rotational power to the output shaft. The control device includes a continuously variable transmission control unit configured to generate a control signal of the continuously variable transmission unit such that the other power generated by the conversion unit exceeds the other power input to the reconversion unit.

A work vehicle includes: an engine; a hydraulic pump that is driven by the engine; hydraulic cylinders that are extended and contracted by pressurized fluid delivered from the hydraulic pump; a work device that is moved according to the extension/contraction operations of the hydraulic cylinders; a travel device that is driven independently of the work device; an electrically driven motor that is driven by electric power generated by the engine to operate the travel device; and a controller that controls the hydraulic cylinders and the electrically driven motor. The controller controls the output power of the hydraulic pump and the output power of the electrically driven motor by changing the distribution ratios of a first torque consumed by the work device and a second torque consumed by the travel device among torques output by the engine, on the basis of a reaction force received by the vehicle body.

A method for driving a transmission mechanism output power in response to an anticipated fluid-pressure gradient field is provided. The method includes sensing the change of direction of pressure gradient field at a desired location from the different area of the transmission mechanism within fluid. The method further includes constructing fluid-pressure gradient field based upon isolation-fluid apparatus or low-density fluid space installed on a transmission mechanism within fluid.

A method for driving a transmission mechanism output power in response to an anticipated fluid-pressure gradient field is provided. The method includes sensing the change of direction of pressure gradient field at a desired location from the different area of the transmission mechanism within fluid. The method further includes constructing fluid-pressure gradient field based upon isolation-fluid apparatus or low-density fluid space installed on a transmission mechanism within fluid.