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

The thermal deflection of the coupling bracket under heat load

Answer

The looseness in the dial indicator stem caused by vibration

Answer

The distortion of the indicator mounting bracket due to magnetic fields

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 rotational speed of the shaft

Answer

The temperature of the shaft surface

Answer

The vibration amplitude at the coupling location

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

Soft foot

Answer

Resonance

Answer

Looseness

Question 4

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

Accepted Answer

Gear coupling

Answer

Rigid flange coupling

Answer

Disc pack (diaphragm) coupling

Answer

Jaw (spider) coupling

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

The maximum permissible misalignment at operating speed

Answer

The alignment tolerance for low-speed machinery below 1,800 RPM

Answer

The zero reference position set before taking alignment measurements

Question 6

What is the recommended hold-down bolt tightening sequence to minimize soft foot when installing machinery?

Accepted Answer

Tighten diagonally opposite bolts in a star pattern, gradually increasing torque in multiple passes

Answer

Tighten all bolts simultaneously using an air wrench

Answer

Tighten from front to back, one row at a time

Answer

Tighten the highest bolt first, then work downward

Question 7

For a machine running at 3,600 RPM (60 Hz), what is the industry-standard acceptable residual misalignment for precision alignment?

Accepted Answer

≤ 0.002 inch (0.05 mm) offset and ≤ 0.5 mrad angle

Answer

≤ 0.010 inch (0.254 mm) offset and ≤ 1.0 mrad angle

Answer

≤ 0.005 inch (0.127 mm) offset and ≤ 2.0 mrad angle

Answer

≤ 0.020 inch (0.508 mm) offset and ≤ 3.0 mrad angle