In a transmission structure according to this invention, speed change ratios of input side first and second transmission mechanisms are set so that the rotational speed of a planetary second element is the same when an HST output is set to a second HST speed in either a first transmission state or a second transmission state, and the rotational speed of a planetary first element is the same when the HST output is set to the second HST speed in either the second transmission state or the first transmission state. The speed change ratios of an output side first and second transmission mechanisms are set so that the rotational speed developed in a speed change output shaft when the HST output is set to the second HST speed is the same in either the first or second transmission states.

In a transmission structure according to this invention, speed change ratios of input side first and second transmission mechanisms are set so that the rotational speed of a planetary second element is the same when an HST output is set to a second HST speed in either a first transmission state or a second transmission state, and the rotational speed of a planetary first element is the same when the HST output is set to the second HST speed in either the second transmission state or the first transmission state. The speed change ratios of an output side first and second transmission mechanisms are set so that the rotational speed developed in a speed change output shaft when the HST output is set to the second HST speed is the same in either the first or second transmission states.

A soil processing machine, in particular a soil compactor, includes a hydraulic steering system with at least one steering element actuated with pressurized fluid and an electrohydraulic pressurized fluid source with at least one steering pressurized fluid pump that can be driven by at least one electric motor for feeding pressurized fluid into a steering pressurized fluid circuit.

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.

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 power transmission device includes a first shaft provided to be rotatable around a first rotational axis of the hydraulic pump driven by the engine. A second shaft is rotatable about the first rotational axis to rotate the power take shaft. A clutch is rotatable about a second rotational axis that is substantially parallel to the first rotational axis and is vertically below the first rotational axis. The clutch has a first rotating portion and a second rotating portion arranged to face each other in the second rotational axis. A first rotating portion is connectable to and separable from the second rotating portion. The first rotation transmission mechanism is configured to transmit rotation of the first shaft to the first rotating portion. A second rotation transmission mechanism is configured to transmit rotation of the second rotating portion to the second shaft.

A power transmission device includes a first shaft provided to be rotatable around a first rotational axis of the hydraulic pump driven by the engine. A second shaft is rotatable about the first rotational axis to rotate the power take shaft. A clutch is rotatable about a second rotational axis that is substantially parallel to the first rotational axis and is vertically below the first rotational axis. The clutch has a first rotating portion and a second rotating portion arranged to face each other in the second rotational axis. A first rotating portion is connectable to and separable from the second rotating portion. The first rotation transmission mechanism is configured to transmit rotation of the first shaft to the first rotating portion. A second rotation transmission mechanism is configured to transmit rotation of the second rotating portion to the second shaft.

A hydraulic driving device of a suction car includes a HST circuit, a suction actuator, a supply channel and a switching valve. In the HST circuit, a first connection channel and a second connection channel connect between a traveling drive pump and a traveling motor in a closed circuit. The suction actuator suction drives a suction device by being actuated by a hydraulic pressure. The switching valve allows oil discharged from the traveling drive pump to the first connection channel to be supplied to the traveling motor in a first operation state. The switching valve allows oil discharged from the traveling drive pump to the first connection channel to flow into the supply channel and be supplied to the suction actuator in a second operation state.

A hydraulic driving device of a suction car includes a HST circuit, a suction actuator, a supply channel and a switching valve. In the HST circuit, a first connection channel and a second connection channel connect between a traveling drive pump and a traveling motor in a closed circuit. The suction actuator suction drives a suction device by being actuated by a hydraulic pressure. The switching valve allows oil discharged from the traveling drive pump to the first connection channel to be supplied to the traveling motor in a first operation state. The switching valve allows oil discharged from the traveling drive pump to the first connection channel to flow into the supply channel and be supplied to the suction actuator in a second operation state.

Methods and systems for controlling a hydromechanical transmission are proposed. In one example, a control method for a hydrostatic unit of a hydromechanical variable transmission (HVT) is presented, comprising controlling the hydrostatic unit via a feedforward control architecture including a non-linear, multi-coefficient model, wherein the hydrostatic unit comprises a hydrostatic pump and a hydrostatic motor. A desired differential pressure of the hydrostatic unit or a desired hydraulic pump displacement may be used as inputs for the model, where the model's output is a pressure difference for a pump control piston coupled to a swash plate of the hydrostatic unit. Use of the non-linear model permits the hydrostatic unit to be controlled based on load, speed, and/or torque, thereby increasing the adaptability of the control system.