| 摘要 |
A hydromechanical transmission provides four gear ranges, the first of which provides a reverse gear range and a low gear range, and the fourth of which is an overdrive range. The transmission utilizes either four or five planetary gearsets and four sequentially actuated clutches, two of which act as brakes. The hydraulic section uses a fixed displacement hydraulic unit and a variable displacement hydraulic unit which alternately act as a pump or a motor. The hydraulic section adds to or substracts from the mechanical gear ratio in a differential arrangement which also acts as range gearing to provide an infinitely variable transmission. Most or all rotating elements move as a unit at three operating points, idle, mid-second-gear, and direct drive, to reduce losses at typical operating points and allow a stepless transition to a locked direct drive.
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