Abstract: The present invention includes an input side transmission unit that transforms the rotation of the input shaft that rotates by receiving input rotation into N steps, and transmits the transformed rotation to the counter shaft; and an output side transmission unit that includes a first planet gear train and a second planet gear train, and that transforms the rotation of the counter shaft and outputs the transformed rotation to the output shaft.

Abstract: A gearbox mounted between axles for left and right follower wheels of a vehicle includes a countershaft parallel to the axles. The countershaft is rotated at a speed greater than those of the right axle by speed-increasing gears. The countershaft and the left axle are capable of being connected to each other through first and second shifting gears and a first hydraulic clutch and through third and fourth shifting gears and a second hydraulic clutch. The first and second hydraulic clutches are disposed back-to-back between the first and third shifting gears and therefore, the size of the entire gearbox can be reduced. Moreover, since the first and second hydraulic clutches are mounted on the countershaft which is rotated at the higher speed, the necessary torque transmitting capacities of the first and second hydraulic clutches can be decreased, leading to reduced sizes of the first and second hydraulic clutches.

Abstract: A hydraulically operated continuously variable transmission comprises a hydraulic pump and a hydraulic motor having a motor cylinder including an integral tubular member. A distribution disc is coupled to the motor cylinder at one end of the tubular portion and has oil passages communicating with the hydraulic pump and the hydraulic motor. A hollow fixed shaft is inserted in the tubular member, and a distribution ring is axially movably mounted on the fixed shaft and has an end face slidably held against the distribution disc. A mechanical seal assembly includes an annular rotatable seal member rotatably disposed in the tubular member, and an annular fixed seal member axially movably, but nonrotatably, mounted on the fixed shaft.