Robert Boschgmbh

Hugo Preun

Wilhelm Zirps

Heinz Flaschar

Peter Kroll

Heinz Kleinschmidt

Petrus Thomassen

The hydraulic lifting device for harvesting machines includes a hydraulic cylinder-piston unit mounted on the wheel frame of the machine and supporting most of the weight of the harvesting apparatus so that the latter abuts against the ground with residual weight only. The cylinder-piston unit is controlled by a multi-way selector valve and a locking valve unit connected in a first working pipeline system. The hydraulic device further includes a pressure limiting valve for setting a reference pressure for the hydraulic cylinder-piston unit, the limiting valve being connected in an additional working pipeline that is branched upstream the limiting valve to a nonreturn valve and therefrom is connected by a direct conduit to a hydraulic accumulator and the hydraulic cylinder-piston unit. The combination of the pressure limiting valve with the non-return valve and the branch conduit prevents during the lowering of the piston-cylinder unit the hydraulic accumulator from being completely discharged, accelerates the lowering movement and improves the seal of the entire lifting device.

Hydraulic lifting device for harvesting machines

A control arrangement for supplying pressure fluid through a supply conduit from a source of pressure fluid to at least two hydraulically operated consumer devices includes, for each of the consumer devices, a valve having a valve member movable axially between a neutral position preventing flow of pressure fluid to the respective consumer device and two working positions respectively connecting the consumer device to the source of pressure fluid or a return conduit. A throttle is located in the supply conduit between a first point of the latter from which a first branch conduit branches off to a first of the valves and a second point from which a second branch conduit branches off to the second of the valves. The arrangement includes further a control valve and a control circuit therefor, controllable at least by the valve member of one of the valves. In the neutral position of all valve members the supply conduit is connected with the return conduit to form therewith a neutral fluid circulation passage.

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Asperg, Germany

Hugo Preun