The combine hydraulic system is an open center system. In an open center system the pump runs continuously, even when system components are not activated (system is in neutral). When the system is in neutral, oil flows through the system and back to the reservoir - the "open center" feature.

There are two reservoirs in the hydraulic system; the hydraulic/hydrostatic reservoir and the steering/engine gearcase reservoir. The hydraulic/hydrostatic reservoir supplies oil for the hydraulic, reel/belt pickup and hydrostatic systems. The steering/engine gearcase reservoir supplies oil for the steering, separator engage wet clutch, gearcase lubrication and unloading auger engage systems.

There are two oil coolers; one each for the reservoirs. Oil cooler bypass valves provide quick warm-up of the oil in cold weather.

There are three oil filters providing filtration for the hydrostatic system, the steering/engine gearcase system and the combined return oil from the hydraulic and reel/belt pickup systems.

There are three pumps supplying oil to the steering/engine gearcase system, hydraulic system and the reel/belt pickup system. The hydrostatic system uses it's own charge pump to supply oil to the hydrostatic unit.

CAUTION: It is normal for the system to allow a raised feeder house (with or without a header) to slowly lower to the ground after a long period of time. Always lower the safety stop when the combine is unattended. If the feeder house should lower itself to the ground in less than 12 hours (approximate), see your John Deere dealer.

IMPORTANT: The components in this system are built to very close tolerances and have been adjusted at the factory. Do not attempt to service these components except to maintain proper oil level and to change oil and filter. See your John Deere dealer for all other service.

HX,AG,SF7184 -19-20MAR90-1/1