Vickers, Inc.

Trinova Limited

Sten Frodin

Thomas Dahl

The invention relates to a hydraulic fluid reservoir comprising a substantially cylindrical wall (1), an upper wall (2) and a lower wall, and two tubular connection pieces (4, 5) for entering and discharging hydraulic fluid into and out from the interior of the reservoir. The two tubular connection pieces, an inlet connection piece (4) and an outlet connection piece (5) are substantially tangentially connected to the cylindrical wall (1) to preserve the momentum of a fluid fed into the reservoir.

Hydraulic fluid reservoir

In the field of fluid power control, there is a need for a control scheme that supplies working fluid under pressure to a load in the event of failure of power supplies to control apparatus associated with the circuit. The disclosure relates to a control circuit 10 in which output pressure from a pump 11 is fed to a control piston 13 therefor via a pressure compensator 17. The pressure compensator 17 is biased to disconnect the supply of fluid at outlet pressure when this pressure is below a threshold value, and permit such supply when the outlet pressure exceeds the threshold value determined by the biassing force on the pressure compensator. A proportional control valve 16 may be employed further to counteract the biassing of the pressure compensator 17, whereby to control the threshold pressure at which the compensator 17 operates to feed fluid at control pressure to the piston 13. The invention is of particular use in control circuits eg. for cooling pumps and cooling fans.

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Jarfalla, Sweden

Sten Frodin