GB844762A - Apparatus for measuring gears and the like - Google Patents

Abstract

844,762. Gauging gear-teeth. HOFLER, W. Sept. 4, 1956 [Sept. 7, 1955], No. 26979/56. Class 106 (2). [Also in Group XXXVIII] Apparatus for measuring recurring distances, e.g. tooth pitch on gears or racks, comprises two feelers for engaging surfaces the distance between which is to be measured, one of the feelers being rotatable, each of the feelers being associated with one electrode of a capacitor determining the frequency of an oscillator which is indicative of the spacing. As shown (Fig. 1), the tooth pitch on a gear-wheel 51 is measured by the spacing between a fixed feeler 62 and a spring-loaded feeler 55 rotatable about a pin 58. Fixed arms 64, 65 help to locate the device relative to the gear 51. The feelers and arms are carried by a plate 54 supported by balls on a fixed base-plate 52, so that plate 54 is freely movable manually to the position shown, where the tips of arms 64, 65 engage with the roots 68 of the teeth, and the ends of feelers 55, 62 are in contact with adjacent tooth faces 59, 69, and plate 54 moves with the gear 51 while the measurement is being made. Feeler 55 carries an electrode 60 (Fig. 3) which co-operates with a fixed electrode 61 to form a capacitor determining the frequency of an oscillator whose output is mixed with that from a fixed frequency oscillator, and the beat frequency, which is recorded and indicated on a meter, indicates the variation in tooth pitch.