The Vibrometer - A Draft Load Vibrating Reed Sensor

A small strip of spring steel is integrally mounted in a counterbored hole in a draft bar so that a tension or compression load on the bar will change the length and load on the strip, changing its natural frequency. A magnetic circuit is used to (1) disturb the strip, to keep it vibrating, and (2) sense the vibration frequency. The design parameters are explored, and laboratory and field test data are presented.