This speed sensor monitors the rotational speed of a gearbox output shaft. It generates a pulsed electrical signal that the tractor’s electronic control unit uses to calculate ground speed or implement PTO speed. A failed sensor causes the speedometer or rate controller to show zero or erratic readings, which can trigger warning lamps or derate engine power. This component is manufactured to the same electrical and mechanical specifications as the original, ensuring the signal amplitude and pulse width match the control unit’s expected input. When reinstalling, ensure the sensor tip is clean and the air gap to the tone wheel is set to the specified clearance.