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.

Feed drive pumpDisplacement according to the cutting length setpoint

Solenoid coil (Y255) is accordingly energized by PWM. This makes the feed drive variable-displacement pump (253) swing to the feeder mode, i.e. a displacement according to the pre-selected cutting length. The feeder quick stop solenoid valve (Y257) is energized. The feeder quick stop valve (791) is in its open position. Multi-function valve (792) restricts the high pressure for the feeding process to 420 bar. 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). When feeding, oil is flushed out of the pump / motor hydraulic circuit via the open shut-off valve (794-2).