Types of dial test indicators(DTI)

Usually, dial test indicators are similar to‘clocks�?because of the appearance of the dial and pointer. They measure the displacement of a plunger or stylus and indicate the magnitude of the displacement on a dial by means of a rotating pointer. There are two main types of dial test indicator.
Plunger type
This type of instrument relies upon a rack and pinion mechanism to change the linear (straight-line) movement of the plunger into rotary motion for the pointer. A gear train is used to magnify the movement of the pointer. This type of instrument has a long plunger movement and is , therefore, fitted with a secondary scale to count the number of revolution made by the main pointer. A large range of dial range of dial diameters and markings is available. Dial test indicators are also widely used for setting up workpieces, and aligning work holding devices on machine tools.
Lever type
This type of instrument uses a lever and scroll to magnify the displacement of the stylus. Compared with the plunger type, the lever type instrument has only a limited range of movement. However, it is extremely popular for inspection and machine setting because it is more compact and the scale is more conveniently positioned for these applications.