Smooth Operation Asphalt Paver Sensor S1800-3 PN 2331721 Ultrasonic Level Sensor for Road Paving The S1800-3 asphalt paver ultrasonic level sensor (part number 2331721) is a precision-engineered grade control component designed for smooth operation on modern road paving machines. It provides accurate, real-time elevation feedback to the paver control system, helping keep asphalt mats level, uniform and on grade. As an essential part of the automatic leveling system, it