PURPOSE: To provide the speed change controlling mechanism of a cheap and highly reliable hydraulic transmission which can automatically determine the speed change rate coping with engine speed and motor load.
CONSTITUTION: The inclined shaft center of a swash plate 19 for a motor is arranged at a position radially deviated from the shaft center of the motor so that the swash plate for the motor may move inclined due to the reaction force of a plunger for the motor coping with the increase in motor load, and the swash plate 19 for the motor is interlockedly connected by the piston 35 fitting in the hydraulic cylinder 36 of a hydraulic actuator A1 for controlling speed change. In the hydraulic cylinder 36, a coil spring 81 is incorporated to energize the piston 36 in a direction to increase the inclination angle of the swash plate 19 for the motor and the oil chamber 82 in the hydraulic cylinder 36 is communicated to a governor hydraulic pressure source in which pressure increases corresponding to the increase in engine speed so as to raise the swash plate 19 of the motor resisting the coil spring 81.
SHIBATA TOSHIYOSHI
SAEKI MASANOBU
