Abstract: A proportional directional control valve in combination with a pressure compensator flow rate control valve opening towards a reservoir and a pressure unloading valve in the load- pressure- carrying control line for the compensator valve are provided to actuate the telescopic cylinder of a tipper truck. The valve device is connected to a pump of constant displacement. The operating speed of the telescopic cylinder is independent from the load to be lifted and the driving speed of the pump. Upon reaching a predetermined load pressure the pressure unloading valve is activated and the load pressure engaging the compensator valve towards closing direction is reduced via the reservoir such that the compensator valve opens and the pump displacement volume returns to the reservoir.

Abstract: The sweeping roller of a sweeping machine is held on the ground in sweeping operation by two hydraulic cylinders in such a manner that the degree of wear is small. For this purpose in each cylinder a static and different holding pressure must be set. The higher pressure is set at a pressure-limiting valve and the lower pressure at the series circuit parallel thereto of a nozzle with an adjustable throttle.