| 摘要 |
<p>Control system for a hydrostatic transmission of the type including a prime mover driven variable displacement pump, the displacement of which is controlled by a pair of strokers (28, 30). Flow of pressurized control fluid from the charge pump to one of the strokers, and from the other stroker to tank, is controlled by a main control valve (34). The control system includes an auxiliary control valve (44) defining passages (98, 100, 102) communicating between the lines connecting the main control valve and the strokers. The auxiliary control valve includes an on-off, electro-hydraulic valve (46) which prevents flow through the auxiliary valve in response to an electrical signal in one condition, and permits flow in response to an electrical signal in another condition. The electrical signals to the electro-hydraulic valve are generated by control logic (52) which alternates the electric signal between the one condition and the other condition at a duty cycle which varies proportional to the amount of pump destoke needed to prevent stalling of the prime mover. </p> |
