Measuring the Idler with Depth Gauge Place the Depth Gauge against the higher centre of the idler. Making sure the Depth Gauge is flat against the Idler, push the pin down to rest firmly against the lower section of Idler. Measure the pin length with a ruler or tape measure. Was this article helpful? Yes No Related Articles Caterpillar – Track Roller How to Measure Excavators – Download Measuring the Sprocket with Callipers Measuring Track Roller with Depth Gauge Measuring the Track Roller with Callipers Measuring the Track Roller with UT Need Support?Can't find the answer you're looking for?Contact Support