Abstract: A roller degradation monitor device monitors the diameter of escalator rollers during operation of the escalator. A cam plate is mounted proximate the roller track for sequential contact with the upper circumference of rollers as they travel along the track. The vertical displacement of the cam plate is monitored by a proximity switch or sensor, differences in cam plate practice from an established baseline signifying variations in roller diameter. The output of the proximity switch or sensor provides a continuous measure of wear and decrease in diameter of the rollers. When the wear exceeds a predetermined value an alarm can be actuated.