GB253612A - Improvements in or relating to adjusting devices for electrical instruments - Google Patents

Abstract

253,612. India, Rubber, Gutta Percha, & Telegraph Works Co., Ltd., Spinks, W. G., and Keeley, T. J. March 20, 1925. Wireless tuning-apparatus, adjustment devices for.-In coarse and fine adjustment mechanism for electrical precision instruments such as variable condensers, inductances, &c., having two co-operative gear members, and wherein the operating-spindle connected with one of the members is mounted so that it is free to rotate about its longitudinal axis when the gears are in mesh, and to swing about a transverse axis when the gears are unmeshed, the operating-spindle is mounted at one end to provide for the movements referred to. As shown, applied to a variable condenser, Fig. 2, the operating-spindle 13 carries a worm 10 meshing with a wheel located under the instrument dial, the spindle being mounted at one end in a ball bearing 14 and passing through a cam slot 18 in a plate 15, Fig. 5, which forms part of an attachment plate 16. A spring 19 keeps the gears in mesh and together with the cam slot forms a snap-over locking device for the spindle in either of its positions. Alternatively the cam surface may be formed on the spring itself. The plate 15 is provided with a zero mark 20 and the operating-spindle with a scale drum 21. Another pointer 23 extending from the balljoint 14 co-operates with the main scale. As applied to an inductance, Fig. 6, the movable coil holder spindle 24 carries a worm wheel 110 and is provided with rubbing electrical contacts 28. The device may be in the form of an attachment which may include the wheel 110.