In a self-propelled construction machine (1), in particular road milling machine, comprising a machine frame (8), at least three travelling devices (12, 16), at least one working device, in particular a milling drum (6), for working the ground pavement (3), at least one hydraulic drive system (70) for driving at least two travelling devices (12, 16), wherein the hydraulic drive system (70) comprises at least one hydraulic pump (78), wherein the hydraulic drive system (70) comprises at least one hydraulic fixed displacement motor (74) for driving at least one driven travelling device, and one each hydraulic variable displacement motor (72) for driving the remaining driven travelling devices that are not driven by a fixed displacement motor (74), wherein a first gearbox (90) is arranged between the fixed displacement motor (74) and the associated travelling device, and wherein one each second gearbox (92) is arranged between the remaining driven travelling devices and the respective hydraulic variable displacement motors (72),
it is provided for the following features to be achieved: the transmission ratio of the first gearbox between the fixed displacement motor (74) and the associated travelling device is lower than the respective transmission ratios of the second gearboxes (92), which are each arranged between the respective hydraulic variable displacement motors (72) and the respective travelling device, and/or the displacement volume of the fixed displacement motor (74) is smaller than the maximum displacement volume of the variable displacement motors (72).

A transmission (21) as a power transmission device for a vehicle comprises an input shaft (22), an output shaft (23), and a planetary continuously variable transmission mechanism (31). The planetary continuously variable transmission mechanism (31) comprises a planetary gear mechanism (32), a pump side clutch (33), a hydraulic pump (36), a hydraulic motor (38), and a motor side clutch (40). The hydraulic pump (36) and the hydraulic motor (38) are connected via a pair of main lines (37A, 37B). When the transmission (21) is switched from a traveling state to a neutral state, at least one clutch (33, 40) of the pump side clutch (33) and the motor side clutch (40) is released.

A transmission (21) as a power transmission device for a vehicle comprises an input shaft (22), an output shaft (23), and a planetary continuously variable transmission mechanism (31). The planetary continuously variable transmission mechanism (31) comprises a planetary gear mechanism (32), a pump side clutch (33), a hydraulic pump (36), a hydraulic motor (38), and a motor side clutch (40). The hydraulic pump (36) and the hydraulic motor (38) are connected via a pair of main lines (37A, 37B). When the transmission (21) is switched from a traveling state to a neutral state, at least one clutch (33, 40) of the pump side clutch (33) and the motor side clutch (40) is released.

A hydromechanical continuously variable speed transmission is provided. The hydromechanical continuously variable speed transmission can include: the HST 10 in which the planetary gear mechanism 11 is housed in the planetary gear support case 71 mounted on a face of the center section 35 to form the HMT unit 100, the face being on the side opposite to the side on which the HST case 23 is mounted, and the HMT unit 100 is further provided with the housing mounting face 35d for fixing the HMT unit 100 to the housing 91 of the traveling power transmission mechanism 89, the housing mounting face 35d being provided on the center section 35 so as to surround the outer circumference of the mounting face 71a on which the planetary gear support case 71 is mounted.

A hydromechanical continuously variable speed transmission is provided. The hydromechanical continuously variable speed transmission can include: the HST 10 in which the planetary gear mechanism 11 is housed in the planetary gear support case 71 mounted on a face of the center section 35 to form the HMT unit 100, the face being on the side opposite to the side on which the HST case 23 is mounted, and the HMT unit 100 is further provided with the housing mounting face 35d for fixing the HMT unit 100 to the housing 91 of the traveling power transmission mechanism 89, the housing mounting face 35d being provided on the center section 35 so as to surround the outer circumference of the mounting face 71a on which the planetary gear support case 71 is mounted.

An agricultural vehicle has an engine, a threshing rotor, and a rotor drive system including a planetary gear assembly and a fluid circuit for driving the rotor at a constant acceleration during a start-up procedure of the rotor.

An agricultural vehicle has an engine, a threshing rotor, and a rotor drive system including a planetary gear assembly and a fluid circuit for driving the rotor at a constant acceleration during a start-up procedure of the rotor.

A speed-changing device (21) is provided with an input shaft (22), an output shaft (23), a planetary gear mechanism (29), a first variator (33), a second variator (34), and a controller (25). The planetary gear mechanism (29) is configured to include a carrier (29A) connected to the input shaft (22), a first sun gear (29B) connected to the first variator (33), and a second sun gear (29C) connected to the output shaft (23). The second variator (34) transmits power transmitted from the first variator (33) to the output shaft (23), or transmits power transmitted from the output shaft (23) to the first variator (33). The controller (25) changes the rotation speed of the first variator (33), thereby changing the rotation speed of the output shaft (23) in relation to the rotation speed of the input shaft (22).

A hydromechanical continuously variable speed transmission is provided. The hydromechanical continuously variable speed transmission can include: the HST 10 in which the planetary gear mechanism 11 is housed in the planetary gear support case 71 mounted on a face of the center section 35 to form the HMT unit 100, the face being on the side opposite to the side on which the HST case 23 is mounted, and the HMT unit 100 is further provided with the housing mounting face 35d for fixing the HMT unit 100 to the housing 91 of the traveling power transmission mechanism 89, the housing mounting face 35d being provided on the center section 35 so as to surround the outer circumference of the mounting face 71a on which the planetary gear support case 71 is mounted.

A hydromechanical continuously variable speed transmission is provided. The hydromechanical continuously variable speed transmission can include: the HST 10 in which the planetary gear mechanism 11 is housed in the planetary gear support case 71 mounted on a face of the center section 35 to form the HMT unit 100, the face being on the side opposite to the side on which the HST case 23 is mounted, and the HMT unit 100 is further provided with the housing mounting face 35d for fixing the HMT unit 100 to the housing 91 of the traveling power transmission mechanism 89, the housing mounting face 35d being provided on the center section 35 so as to surround the outer circumference of the mounting face 71a on which the planetary gear support case 71 is mounted.