A pump operation piston biased by a neutral spring mechanism and a larger volume operation spring biased by a larger volume operation spring in a larger volume direction operatively move pump and motor volume adjusting members, respectively, is provided. A first pressure control valve commonly controls supply-discharge of pressure oil that presses the pump operation piston in a first slide direction and the motor operation piston in a smaller volume direction. A second pressure control valve controls supply-discharge of pressure oil that presses the pump operation piston in a second slide direction. Biasing forces of the neutral spring mechanism and the larger volume operation spring are so set that, after the pump operation piston is moved in the first slide direction by a predetermined distance, the motor operation piston starts moving.

A pump operation piston biased by a neutral spring mechanism and a larger volume operation spring biased by a larger volume operation spring in a larger volume direction operatively move pump and motor volume adjusting members, respectively, is provided. A first pressure control valve commonly controls supply-discharge of pressure oil that presses the pump operation piston in a first slide direction and the motor operation piston in a smaller volume direction. A second pressure control valve controls supply-discharge of pressure oil that presses the pump operation piston in a second slide direction. Biasing forces of the neutral spring mechanism and the larger volume operation spring are so set that, after the pump operation piston is moved in the first slide direction by a predetermined distance, the motor operation piston starts moving.

A first gear mechanism is connected to an input shaft. A second gear mechanism is connected to the input shaft. A motor is connected to the first gear mechanism and the second gear mechanism. The motor continuously varies a speed ratio of a first output gear with respect to the input shaft and a speed ratio of a second output gear with respect to the input shaft. A planetary gear mechanism includes a first rotation element, a second rotation element, and a third rotation element. The planetary gear mechanism is rotatable about a first transfer shaft. A first driven gear is rotatable about a second transfer shaft. The first output gear is connected to the first rotation element. The second output gear is connected to the second rotation element through the first driven gear. The output shaft is connected to the third rotation element.

A first gear mechanism is connected to an input shaft. A second gear mechanism is connected to the input shaft. A motor is connected to the first gear mechanism and the second gear mechanism. The motor continuously varies a speed ratio of a first output gear with respect to the input shaft and a speed ratio of a second output gear with respect to the input shaft. A planetary gear mechanism includes a first rotation element, a second rotation element, and a third rotation element. The planetary gear mechanism is rotatable about a first transfer shaft. A first driven gear is rotatable about a second transfer shaft. The first output gear is connected to the first rotation element. The second output gear is connected to the second rotation element through the first driven gear. The output shaft is connected to the third rotation element.

The invention relates to a power split gearbox for a motor vehicle. The power split gearbox comprises a drive shaft which can be connected to an internal combustion engine in order to feed in torque, a first mechanical branch with a planetary gear mechanism arrangement, an infinitely variable second branch which can be connected to the first branch and comprises two adjustable energy converters which can be coupled to one another in energy terms and can be operated in each case in both directions, and at least one output shaft which can be coupled to the drive shaft via the first and the second branch. At least one first reversing stage is provided between the drive shaft and the output shaft for changing between at least one first forward driving range and at least one first reverse driving range, wherein the reversing stage either reverses or keeps constant all of the rotational directions of the sun gears, the internal gear and the spider shaft during changing between the first forward driving range and the first reverse driving range.

The invention relates to a power split gearbox for a motor vehicle. The power split gearbox comprises a drive shaft which can be connected to an internal combustion engine in order to feed in torque, a first mechanical branch with a planetary gear mechanism arrangement, an infinitely variable second branch which can be connected to the first branch and comprises two adjustable energy converters which can be coupled to one another in energy terms and can be operated in each case in both directions, and at least one output shaft which can be coupled to the drive shaft via the first and the second branch. At least one first reversing stage is provided between the drive shaft and the output shaft for changing between at least one first forward driving range and at least one first reverse driving range, wherein the reversing stage either reverses or keeps constant all of the rotational directions of the sun gears, the internal gear and the spider shaft during changing between the first forward driving range and the first reverse driving range.

Methods and systems for a hydromechanical transmission are provided. In one example, the method includes responsive to rotation of a portion of a mechanical assembly induced by cranking of an engine, blocking an output shaft of the hydromechanical transmission via joint engagement of a forward drive clutch and a reverse drive clutch. The method further includes pressurizing a hydrostatic assembly while the forward drive clutch and the reverse drive clutch remain jointly engaged, where the mechanical assembly is coupled in parallel with the hydrostatic assembly.

Methods and systems for a hydromechanical transmission are provided. In one example, the method includes responsive to rotation of a portion of a mechanical assembly induced by cranking of an engine, blocking an output shaft of the hydromechanical transmission via joint engagement of a forward drive clutch and a reverse drive clutch. The method further includes pressurizing a hydrostatic assembly while the forward drive clutch and the reverse drive clutch remain jointly engaged, where the mechanical assembly is coupled in parallel with the hydrostatic assembly.

A transmission structure of the present invention changes capacity of pump body so that vehicle speed detected by vehicle speed sensor increases and reduces according to speed-increasing and speed-reducing operations of speed-change operating member while fixing capacity of motor body at a low-speed motor capacity when the vehicle speed is equal to or lower than a switching speed that is realized by setting motor body to the low-speed motor capacity and setting the pump body to a predetermined pump switching capacity, and changes capacity of motor body so that vehicle speed increases and reduces in accordance with speed-increasing and speed-reducing operations of speed-change operating member while fixing capacity of the pump body at the pump switching capacity when vehicle speed is higher than the switching speed.

A transmission structure of the present invention changes capacity of pump body so that vehicle speed detected by vehicle speed sensor increases and reduces according to speed-increasing and speed-reducing operations of speed-change operating member while fixing capacity of motor body at a low-speed motor capacity when the vehicle speed is equal to or lower than a switching speed that is realized by setting motor body to the low-speed motor capacity and setting the pump body to a predetermined pump switching capacity, and changes capacity of motor body so that vehicle speed increases and reduces in accordance with speed-increasing and speed-reducing operations of speed-change operating member while fixing capacity of the pump body at the pump switching capacity when vehicle speed is higher than the switching speed.