| 摘要 |
<p>An infinitely variable belt-drive transmission for an engine comprises a primary pulley (36) having a hydraulically shiftable disc (36b), a secondary pulley (37) having a hydraulically shiftable disc (37b), a belt (34) engaged with both pulleys, and a hydraulic circuit. A transmission ratio control valve (70) having a spool (72) responds to engine speed to control the oil and to shift the disc of the primary pulley (36) to change the transmission ratio. Pitot pressure dependent on engine speed is applied to the spool (72) to shift it against a spring (74) the force of which is determined by the depression of the accelerator pedal (80a). An actuator (100) can increase the load on the spring (74) to downshift the transmission. A manual selector device operates the actuator (100) to cause downshifting.</p> |
