| 摘要 |
<p>A method of shifting a transmission having both a hydrostatic portion, including a variable pump (15), and a hydraulic motor (29), and a mechanical transmission (33) portion, including a shift cylinder (37). The method includes relieving the output torque of the motor (29), shifting the mechanical transmission to neutral, and controlling the displacement of the pump (15) to synchronize motor output speed with the required input speed to the desired gear ratio of the mechanical transmission (33). Then fluid flow to the shift cylinder (37) occurs to shift to the desired gear ratio. In accordance with an important aspect of the invention, the shifting method includes a series of steps in which the feasibility of the prospective shift is determined, and only when the prospective shift can be completed, without detriment to the operation of the vehicle, will the shift be completed. As a result, the shifting between low gear and high gear can occur without bringing the vehicle to a stop each time. <IMAGE></p> |
