| 摘要 |
A multiple substantially identical countershaft powershift transmission is provided. The transmission (10) comprises an input shaft (12) and preferably three (16, 18 and 20) input gears and an output gear (22) concentric and rotatable relative thereto. A plurality of substantially identical countershaft assemblies (42, 42A) carrying countershaft gears (54, 56, 58 and 60) constantly meshed with the input gears and output gear surround the input shaft and an output shaft (24) generally coaxial with inpout shaft (12) and carrying the output gear (22) rotationally fixed thereto are provided. A first double acting friction clutch mechanism (26) for selectively frictionally coupling first speed input gear (16) or third speed input gear (18) to the input shaft and a second double acting friction clutch mechanism (28) for selectively coupling second speed input gear (20) or fourth speed output gear (22) are provided and are concentric and driven by the input shaft (12). Means (V, C) are provided for selectively actuating the clutch portions (30, 32, 36 and 38) of the double acting clutch assemblies with overlapping engagement of the clutch portion being released and the clutch portion being applied. |
