| 摘要 |
<p>A hydrostatic transmission, eg for power excavator, has a speed matching device comprising a pressure reduction valve 7 operated by a control pedal 1 and feeds, via fluid line 11, pilot fluid from pilot pump 5 to direction select valve 3. Situated between reduction valve 7 and select valve 3 is a branch line 13 which is connected to fluid line 11 and to hydraulic cylinder 15. The cylinder 15 is attached to a throttle lever 21 of an engine, so that when the pedal 1 is operated the cylinder 15 receives fluid pressure proportional to that in branch line 13 and moves the lever 21 so as to control the engine revolutions. A limit switch 31 is electrically connected to a controller 23 which, via stepping motor 25, controls the lever 21 when full power is required. Signals from controller 23 operates a proportion valve 27 that controls main pumps P1 and P2. A control valve 9 activated by signals from the valve 7 connects the main pumps P1 and P2 with a motor M.</p> |
