Dial indicators and mounting hardware are the equipment needed to take alignment readings.
Dial indicators Figure 54.15 shows a common dial indicator, which is also called a runout gage. A dial indicator is an instrument with either jeweled or plain bearings, precisely finished gears, pinions, and other precision parts designed to produce accurate measurements. It is possible to take measurements ranging from one-thousandth (0.001 inch or one mil) to 50 millionths of an inch.