GB246713A - New or improved operating means for variable electric condensers, variometers and like instruments - Google Patents

Abstract

246,713. Laughton, G. A., and Curry, F. J. June 2, 1925. Wireless tuning-apparatus, adjustment devices for. - Operating means for condensers, variometers and like instruments comprise the arrangement in which 'the instrument spindle is adapted to be rotated either at a slow speed from a setting knob through reduction gearing mounted in or upon a rotatable, but frictionally held, cage or directly by bodily rotation of the cage together with a dial to which the knob is also connected through gearing. The instrument spindle c carries a bush g rotatable in the lower plate h<1> of a cage formed by plates h<1>, h<2> the cage being gripped by a friction device j<1> carrying shoes j. Fast on the bush g is a gear wheel k meshing with a pinion l on a spindle which is rotatably mounted within the cage. The spindle carries a gear wheel l<1> meshing with a pinion m on a similar shaft on which is a gear m<1> engaging a pinion n on a shaft o carrying a knob q. To provide for uniform movement of the dial p, the spindle carrying the pinion l is extended without the cage and carries a pinion r meshing with a gear s secured to the dial p and through which the shaft o passes without touching. For fine adjustment, the knob q is rotated and drives the spindle c slowly through gearing n, m<1>, m, l<1>, l, k, and the dial p in the same direction and at the same speed through gearing r, s, the cage meanwhile remaining stationary owing to the shoes k. For coarse adjustment, the dial p is rotated by means of its fingerpiece p<1> and as no force is applied to the gears, the cage, dial, and spidle rotate together against the frictional force of the shoes j. In the form shown, the knob q will rotate the spindle in a direction opposite to its own, but another gear could be provided to correct this. The shoes eliminate and risk of damage to the parts if stops and used to limit the travel of the spindle. The wheels k, l<1>, m<1>, s are identical and those l, m, n, r are identical to facilitate production.