The Chronometric Type Speed Indicators are contact style instruments that measure the average number of revolutions per minute. After a short interval of 3 or 6 seconds of testing time, the pointers automatically stop at positions which indicate the measured speed.

The dial of these instruments has a black numbered scale that reads directly in revolutions per minute. Surface speeds in feet per minute are obtained by using the supplied 6-in. (152 mm) circumference wheel and dividing the scale reading by 2. An optional 12-in. (304-mm) circumference wheel is available to obtain direct feet per minute readings.

After fitting a suitable accessory tip or wheel on the shaft of the instrument, place the drive tip or wheel in contact with the moving equipment and allow it to rotate evenly.

Press the operating button and release it quickly. The main pointer will begin its rotation and the small pointer will slowly rotate as it accumulates revolutions of the main pointer. After both pointers stop, remove the instrument from the contacted surface and observe the positions of the pointers. The accumulated number plus the main pointer reading equals the averaged speed during that testing period.