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 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 causes, during a period from a time point when a rotational speed of a drive rotational power reaches a predetermined first/second speed stage shift-up start speed until a first/second speed stage shift-up end time point, one of an input-side clutch mechanism pair and an output-side clutch mechanism pair to be in a double transmitting state, and causes, in the double transmitting state, a first clutch mechanism and a second clutch mechanism of the other one of the input-side clutch mechanism pair and the output-side clutch mechanism pair to be shifted to a disengagement sate and an engagement state, respectively, while having frictional plate slid.

A transmission system suitable for operation with a drive machine includes an input shaft for a drive power, at least one output shaft for outputting drive power, a power-split transmission section having at least one variable transmission branch and a mechanical transmission branch, a manual transmission, a transmission system controller, and at least one first and second electric machine for generator and motor operation. The electric machines are electrically connected to one another. The drive power is divided up and conducted by the mechanical and variable transmission branch. An input-coupled, magnetically electric epicyclic gear stage brings together the variable transmission branch and mechanical transmission branch, and is activated by the second electric machine such that the output shaft of the transmission system rotates counter to a direction of rotation at the input shaft to provide a forward and reverse operation of the transmission system.

Methods and systems for a hydromechanical transmission are provided herein. In one example, the transmission system includes a hydrostatic assembly and a mechanical assembly coupled in parallel to a first and second planetary gear sets. The transmission system further includes a plurality of clutches designed to shift between two drive ranges in a set of drive ranges that includes a reverse drive range and two forward drive ranges to adjust the input to output speed ratio of the transmission.

Methods and systems for a hydromechanical transmission are provided herein. In one example, the transmission system includes a hydraulic pump and a hydraulic motor rotationally coupled in parallel with a first planetary gear set and a second planetary gear set. In the system, sun gears of the planetary gear sets are rotationally coupled to the hydraulic motor, a carrier of the first planetary gear set is rotationally coupled to a first clutch and a second clutch, and a ring gear of the second planetary gear set is rotationally coupled to a third clutch.

Methods and systems for a hydromechanical transmission are provided herein. In one example, the transmission system includes a hydraulic pump and a hydraulic motor rotationally coupled in parallel with a first planetary gear set and a second planetary gear set. In the system, sun gears of the planetary gear sets are rotationally coupled to the hydraulic motor, a carrier of the first planetary gear set is rotationally coupled to a first clutch and a second clutch, and a ring gear of the second planetary gear set is rotationally coupled to a third clutch.

Methods and systems for a hydromechanical transmission are provided herein. In one example, the transmission system includes a hydrostatic assembly and a mechanical assembly coupled in parallel to a first and second planetary gear sets. The transmission system further includes a plurality of clutches designed to shift between two drive ranges in a set of drive ranges that includes a reverse drive range and two forward drive ranges to adjust the input to output speed ratio of the transmission.

A work vehicle includes a hydrostatic stepless speed changer device configured to speed-change driving power of an engine steplessly, a plurality of planetary gear speed changer devices configured to speed-change the driving power speed-changed by the stepless speed changer device, a plurality of clutch mechanisms corresponding to the plurality of planetary gear speed changer devices in order to take off the driving powers from these plurality of planetary gear speed changer devices individually, and a traveling speed changer device for speed-changing and transmitting the driving powers transmitted from the plurality of clutch mechanisms to a traveling mechanism. The plurality of planetary gear speed changer devices the plurality of clutch mechanisms and the traveling speed changer device are accommodated in a transmission case.

Systems and methods for controlling transmissions having CVTs are disclosed with multiple modes and gearing arrangements for range enhancements, where embodiments include synchronous shifting to allow the transmission to achieve a continuous range of transmission ratios, while minimizing “empty” cycling of the CVT during mode shifts. Embodiments provide for wide ratio range and performance and efficiency flexibility, while maximizing CVT usage through synchronous shifting.