Hydraulic change-over device for a reversible plough

摘要

The invention relates to a hydraulic change-over device for a reversible plough with a double-acting piston/cylinder unit and a reversing device which switches in a pressure-dependent manner and effects an automatic double stroke. The risk existing in reversing devices which switch in a pressure-dependent manner, namely the risk of a premature switching by means of pressure surges upon starting-up or steep pressure increases in the vicinity of kinematic dead-centre positions, is substantially avoided by means of the incorporation of a valve member in the admission. The valve member consists of a spring-loaded actuating piston with two active surfaces which are directed towards one another, of which the one directed towards the spring is loaded permanently by the admission pressure and the other is loaded by the respective pressure in each working chamber, which is connected to the admission in the first stroke phase. The valve member therefore acts, in the first stroke phase, as a differential pressure regulator which closes in the event of a small pressure gradient. In the second stroke phase it opens even in the event of comparatively small pressures in the admission, since no pressure is exerted on the other active surface.