Damping of electrical measuring instruments

Claim 1

In an electrical measuring instrument having a frame and a rotary moving part capable of longitudinal movement in relation to said frame and including a damping arrangement comprising co-operating first and second pads fitted respectively to said moving part and to said frame to have adjacent surfaces defining a gap between said surfaces, said gap containing viscous liquid held in position by surface tension, the improvement which comprises said first pad being formed of glass-filled plastics material in which a proportion of short glass fibers extend to the surface of the pad and provide a minute degree of roughening to provide a frictional grip on said viscous liquid so as to produce a damping effect and tend to hold the liquid in position in said gap, and said adjacent surfaces of said pads being shaped so that said gap, when seen in cross-section, has substantially parallel sides which diverge at the edge of said gap to provide a collecting area for liuqid expelled from the parallel portion of the gap by vibratory pumping action, whereby expelled liquid can return to the parallel portion of the gap when conditions are stabilized.