Temperature Compensation for Hydraulic Governors
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D1.1 R I NG development work on hydraulic governors, Simms Motor Units Ltd., East Finchley, London, N.2, has devised a method of overcoming the effect of temperature variations on the governed speeds of engines equipped with hydraulically governed fuel pumps, such temperature variations being liable to alter the speed control as a result of changes in oil viscosity.
The device consists of a spindle (A), one end of which is machined at a small angle to the spindle axis. This end partially closes an orifice sd that rotation of the spindle about its axis determines the area of an oil port. A second spindle (B) on the same axis as the first has a control lever (C) at its outer end, whilst connecting the two spindles and immersed in oil from the hydraulic system is a circular temperature-sensitive bimetallic strip (D). When the control lever (C) is set in a fixed position, alteration in oil temperature causes the spindle (A) to rotate and change the area of the orifice, thereby maintaining a constant control pressure.
Simms engineers consider that this device is applicable to any system in which the control pressure is dependent unon the flow of oil through an orifice.