| 摘要 |
<p>A reversible variable displacement pump (3) is controlled by a servomotor (10) coupled to forward and reverse control valves (16, 18) operated by common controller (19) the control pressure also being applied via shuttle valve (21) and valve (42) to a servomotor (28) controlling fuel supply to an engine driving the pump (31). If the pump delivery pressure exceeds a given value during normal drive, valve (42) vents line (23) and isolates line (24), but during braking this valve isolates line (23) from line (24) and vents the latter to provide hydrostatic braking. Engine speed sensor (53) also causes valve (42) to vent line (23) to relieve any overload. Comparator (58) compares the pressure at (24) with a control pressure from valve (57) and closes throttle (35) when the latter pressure is the higher, this pressure then acting on servomotor (28). A vehicle driven by the engine and hydrostatic transmission also includes a lifting device controlled by element (63) and lever (64) which also closes throttle (35) and actuates servomotor (28) via control valve (65) during operation of the lifting device. <IMAGE></p> |
