SPEED PRIMARY APPARATUS FOR A SEWING MACHINE

摘要

The shaft (1) of a sawing machine drives an externallytoothed rotor (6) revolving inside an internally-toothed stator (5), both being ferromagnetic and forming a closed loop magnetic circuit with a permanent magnet (9). The circuit is intersected by a pipe (10) to generate a voltage applied to an amplifier and waveshaping circuit for production of a train of pulses of frequency proportional to machine speed. The magnet (9) is ringshaped and magnetized in direction parallel to the machines shaft (1) axis, and lies between the toothed rotor (6) and a second circular rotor (8) inside a second stator (7).