A tillage implement spanning a lateral distance relative to a forward direction and having a plurality of carrier frames, each for supporting a plurality of soil engaging tools. A pivoting wheel assembly positions the carrier frames at a variable distance from the soil and an actuator is connected between the carrier frame and each support wheel assembly to vary the height of the carrier frame. The actuator has a sensor for generating a signal reflecting the displacement of the actuator. The sensor element is mounted in an adjustable sensor support and countersunk by the required clearance between the sensor element and encoded information on the output shaft so that the sensor support may be adjusted to abut the shaft and accurately position the sensor element.