Question

What is the purpose of a pin which is located in a slot in rack guide in dial indicator?

(a) Prevent movement of plunger perpendicular to its own axis

(b) Prevent rotation of plunger about its own axis

(c) Prevent plunger displacement

(d) Prevent movement of plunger in case of misalignment

I had been asked this question in exam.

I would like to ask this question from Working Mechanism of Dial Indicators in section Dial Indicators and Indicating Gauges of Engineering Metrology

Answer 1

Correct answer is (b) Prevent rotation of plunger about its own axis

Easiest explanation: The plunger rotation about its own axis is prevented by a pin which is located in a slot in a rack guide carries a rack accurately meshing with the pinion. The plunger is a perfect sliding fit in its bearings.