GB116689A - Improvements in Tachometers. - Google Patents

Abstract

116,689. Veigel, A. June 2, 1017, [Convention date]. Centrifugal and magnetic speed indicators; combination of two instruments, indicating high and low speeds respectively.-Apparatus adapted to indicate both high and low speeds, particularly applicable for aeroplane engines, comprises the combination of two types of speed indicators, e.g. a centrifugal and an eddycurrent speed indicator, the first being adapted to indicate high speeds and the second low speeds. A lost-motion device is provided to prevent the centrifugal governor from operating the indicating hand before the desired limit is reached. Two horse-shoe magnets c, d, adjustably secured together by a sleeve and fixed to the driven shaft w, have mounted between them on a spring-controlled indicating shaft m an eddy-current disk b. Sliding on the shaft m is a sleeve f, a shoulder d on which is forced by a spring y on to weighted bell-crank levers k pivoted to the upper magnet. Upward movement of the sleeve f is communicated through a pin g to a fork h and from thence through bevel wheels s, o to a toothed sector p engaging a pinion q on the shaft m. Sufficient play is provided in the fork to prevent the centrifugal device from coming into operation before the desired limit is reached. In a modification, two pointers may be provided, the higher of which may be covered by a screen until required.