| 摘要 |
An engine 11 of a vehicle drives a pump 12 which in turn drives a hydraulic motor 13 which is connected to and drives a transmission 14. A separate pump 17 may be connected to the transmission 14 which detects the speed of the vehicle by being rotated in proportion to the rotation of the output shaft of the transmission 14. A gear change valve 16 may be provided which feeds pressurised oil to a transmission pump to select a first speed clutch 14F or a second speed clutch 14S dependent on a controller 30. When an accelerator pedal 23A is depressed a certain amount, the pressure from the pump 12 is above a certain value, and the vehicle is decelerating, for example, when the vehicle is travelling uphill, the controller 30 sends a shiftdown signal to change from second speed clutch 14S to first speed clutch 14F. |
