Abstract: An asphalt paver tows a device which measures smoothness of the fresh mat laid by the paver. The device measures the distance between the mat and a datum line as a function of paver position. Preferably, the rear reference beam of a dual reference beam paver is provided with a smoothness sensor. The rear beam is supported on two shoes riding on a fresh mat laid by the paver. A device to measure the distance from the beam to the mat such as a potentiometer is located near the center of the rear beam. The potentiometer has its shaft connected to a shoe by a lever so that vertical movement of the shoe rotates the shaft. Movement of the shoe is plotted against movement of the paver determined by a forward travel sensor. The plot shows smoothness of the mat.

Abstract: A sensing arrangement for sensing the level of a bulk material, such as the paving material fed by a paving machine, comprises an ultrasonic transducer spaced from the paving material for controlling the feed of material.