Which instrument is used to check shaft alignment?

Which instrument is used to check shaft alignment?

• A. Micrometer
• B. Dial indicator
• C. Manometer
• D. Sling psychrometer

Answer: (B)

Checking shaft alignment relies on a tool that can precisely sense small shifts in distance as the machine turns. A dial indicator provides that level of precision and is designed to measure tiny linear deviations in position. When assessing two aligned shafts, you mount the indicator so its plunger rests against a reference surface on one shaft (or a coupling hub) and rotate the shafts. Any needle movement reveals misalignment, showing both parallel (offset) and angular (slope) errors. You then adjust the hardware—shim thickness, mounting, or repositioning—until the readings are within the specified tolerance. Micrometers measure small changes in dimensional thickness or diameter but don’t capture the relative, dynamic position between two shafts during rotation. Manometers and sling psychrometers are used for pressure and humidity measurements, respectively, and aren’t related to mechanical alignment.

Checking shaft alignment relies on a tool that can precisely sense small shifts in distance as the machine turns. A dial indicator provides that level of precision and is designed to measure tiny linear deviations in position. When assessing two aligned shafts, you mount the indicator so its plunger rests against a reference surface on one shaft (or a coupling hub) and rotate the shafts. Any needle movement reveals misalignment, showing both parallel (offset) and angular (slope) errors. You then adjust the hardware—shim thickness, mounting, or repositioning—until the readings are within the specified tolerance.

Micrometers measure small changes in dimensional thickness or diameter but don’t capture the relative, dynamic position between two shafts during rotation. Manometers and sling psychrometers are used for pressure and humidity measurements, respectively, and aren’t related to mechanical alignment.