CVA Shaft Alignment & Machinery Installation 2

Question 1

What is 'bracket sag' and how does it affect dial indicator alignment readings?

Accepted Answer

The downward deflection of the dial indicator bracket due to gravity, which introduces a false reading that must be measured and subtracted

Answer

Bracket sag is the gravitational deflection of the dial indicator arm when it extends outward; this sag adds an error to bottom readings and must be measured independently and subtracted from alignment calculations.

Question 2

In laser shaft alignment, what does the detector (PSD) measure?

Accepted Answer

The position of the laser beam striking its surface, which is used to calculate shaft offset and angle

Answer

The position-sensitive detector (PSD) measures the exact X-Y coordinates where the laser beam strikes its surface; changes in beam position as the shafts are rotated are used to calculate misalignment values.

Question 3

What type of misalignment is indicated when vibration phase measurements show a 180° phase difference across the coupling in the radial direction?

Accepted Answer

Parallel (offset) misalignment

Answer

A 180° radial phase difference across the coupling is a classic indicator of parallel misalignment, as the two shaft centerlines are offset and move in opposition to each other.

Question 4

Which coupling type provides the greatest tolerance for angular misalignment while transmitting torque?

Accepted Answer

Gear coupling

Answer

Gear couplings use meshing gear teeth that can accommodate significant angular misalignment (typically up to 1.5° per gear mesh) while transmitting high torque loads.

Question 5

What is 'cold alignment target' or 'alignment offset' in precision machinery installation?

Accepted Answer

An intentional misalignment introduced during cold installation to compensate for predicted thermal growth at operating temperature

Answer

A cold alignment target (thermal offset) intentionally misaligns the machine when cold so that, after thermal expansion at operating temperature, the shafts reach the desired aligned position.

CVA - Certified Vibration Analyst Practice Test

CVA - Certified Vibration Analyst Practice Test

CVA Shaft Alignment & Machinery Installation 2