| 摘要 |
A powershift two-speed gear box is designed as an epicyclic gear box (3). Both gear steps are hydraulically switchable by means of two friction clutches (9 and 10). For that purpose friction elements (outer and inner disks 13, 14 and 19, 20) are alternatively closed and open by the force exerted by plate springs (16, 22) or by hydraulic fluid. Means associated to one of the friction clutches (9 or 10) prevent the full force of the spring from acting on the friction elements when the gear is shifted down from a higher to a lower step. An accumulator (30) is preferably used to influence torque transmission during downshift. An essential advantage of the disclosed arrangement consists in the smoothness of the shifting operation during downshift, avoiding a hard shifting which is felt as particularly disagreeable. |
