Millwright Certification Mechanical Systems 1

Question 1

When aligning a shaft using a dial indicator, what does a total indicator reading (TIR) of zero at all measurement points confirm?

Accepted Answer

The shaft centerlines are perfectly collinear

Answer

A TIR of zero at all points around the rotation confirms that the two shaft centerlines are perfectly collinear — no angular or parallel offset exists. Any runout indicates misalignment that must be corrected before operation.

Question 2

A millwright notices that a ball bearing is running hot and emitting a high-pitched whine. Which condition is MOST likely the cause?

Accepted Answer

Insufficient radial clearance due to over-tightening the locknut

Answer

Over-tightening a locknut preloads the bearing beyond design limits, eliminating internal clearance. The resulting metal-to-metal contact generates heat and the high-pitched whine characteristic of a preloaded or seized bearing.

Question 3

What is the function of a keyway and key in a shaft-to-hub connection?

Accepted Answer

To transmit torque between the shaft and the hub

Answer

A key fits into matching keyways machined in both the shaft and hub, creating a positive mechanical drive that transmits torque. While keys can act as shear elements under extreme overload, their primary designed function is torque transmission.

Question 4

When selecting the correct bearing for a location that experiences combined radial and thrust (axial) loads, which bearing type is MOST appropriate?

Accepted Answer

Angular contact ball bearing

Answer

Angular contact ball bearings are designed with a contact angle that allows them to carry significant axial (thrust) loads in addition to radial loads. Cylindrical roller bearings carry radial loads well but have very limited axial capacity; needle bearings are radial-load-only components.

Question 5

In a worm gear drive, the gear ratio is determined by dividing the number of teeth on the worm wheel by which value?

Accepted Answer

The number of starts (threads) on the worm

Answer

Gear ratio in a worm drive equals the number of worm wheel teeth divided by the number of starts on the worm. A single-start worm advances the wheel one tooth per revolution; a two-start worm advances two teeth, halving the ratio and doubling output speed.

Blog Practice Test

Blog Practice Test

Millwright Certification Mechanical Systems 1