| 摘要 |
PURPOSE: To increase the reliability by execute shuttle shift of a powershift transmission only by operating a possible minimum number of clutches and valves. CONSTITUTION: A powershift transmission 16 includes a plurality of clutches 20, including a final or directional set of clutches. The plurality of clutches are controlled by a plurality of electro-hydraulic direct acting valves 18 and two electro-hydraulic proportional or pressure modulating valves 18. The pressure modulating valves have the function of modulating the pressure supplied to each of the direct acting valves associated with each of the three directional clutches. Vehicle deceleration during a shuttle shift is achieved by releasing all clutches, then gradually pressurizing only two clutches in the directional set. |
