A _______ can be used to determine the clearance between the armature and the pole pieces.

A _______ can be used to determine the clearance between the armature and the pole pieces.

• A. long feeler gauge
• B. micrometer
• C. caliper
• D. ruler

Answer: (A)

Measuring the air gap between the armature and the pole pieces is about checking a very small clearance that directly affects the magnetic circuit. A feeler gauge set lets you determine that gap by trying blades of different thicknesses until you find the one that just fits with a light drag. The thickness of that blade is the clearance value. Using a long feeler gauge is important because the gap runs along the length of the pole face and you need blades that can reach and sit evenly in the narrow space along the full span. Other tools aren’t as suitable: a micrometer measures a single small distance on a single part and isn’t practical for an open, continuous air gap; a caliper or ruler isn’t precise enough for such tiny clearances and may not access the gap properly.

Measuring the air gap between the armature and the pole pieces is about checking a very small clearance that directly affects the magnetic circuit. A feeler gauge set lets you determine that gap by trying blades of different thicknesses until you find the one that just fits with a light drag. The thickness of that blade is the clearance value.

Using a long feeler gauge is important because the gap runs along the length of the pole face and you need blades that can reach and sit evenly in the narrow space along the full span. Other tools aren’t as suitable: a micrometer measures a single small distance on a single part and isn’t practical for an open, continuous air gap; a caliper or ruler isn’t precise enough for such tiny clearances and may not access the gap properly.