Ground drive hydraulics circuit diagram

Item Explanation

P1 Working hydraulics oil pressure (also pre-loaded while diesel engine is OFF) P2 Feed pressure

T Return line to tank

Y255 Feeder drive pump adjustment solenoid valve Y256 Main drive brake valve solenoid valve

Y257 Feeder quick stop solenoid valve

Description of function

Main drive not braked When the main drive is ON, solenoid coil (Y256) is energized. The shut-off valve (794-1) is not switched by the oil pressure P1. The blockage is canceled. The main drive is not braked. Feeder quick stop When the feeder quick stop function is triggered, e.g. by the metal or the stone detector, power supply to the feeder quick stop solenoid valve (Y257) is interrupted. The oil pressure of the pressurised working hydraulics sets the feeder quick stop valve (791) to its shut-off position. In this shut-off position, the oil flow from the feeder drive motor (254) is blocked. The oil flow from the feed drive variable-displacement pump is short-circuited (feed and return lines are connected via valve (791)).

Feed drive pumpapprox. 0displacement after a short delay time

After a short delay time, solenoid coil (Y255) is accordingly energized by 1200mA. This makes the feed drive variable-displacement pump (253) swing to the quick stop operating mode, i.e. approx. 0 displacement. Feed / Oil cooling The feed oil pressure P2 serves for feeding the pump/motor hydraulic circuit via the multi-function valves (792/793). It also serves as variable-displacement oil pressure for variable-displacement pump (253). Oil cooling is achieved by constantly tapping oil into the variable-displacement pump housing via orifice plate (408).