CVA Shaft Alignment & Machinery Installation

Question 1

Which type of shaft misalignment produces high vibration predominantly in the axial direction at 1× and 2× running speed?

Accepted Answer

Angular misalignment

Answer

Parallel misalignment

Answer

Soft foot

Answer

Resonance

Question 2

What is the most common vibration frequency signature associated with parallel (offset) misalignment?

Accepted Answer

Dominant 2× radial vibration

Answer

Dominant 1× with elevated 3× harmonics

Answer

Sub-synchronous vibration below 0.5×

Answer

High-frequency random noise

Question 3

During a soft foot check, what is the maximum acceptable dial indicator reading before corrections must be made?

Accepted Answer

0.002 inch (0.05 mm)

Answer

0.001 inch (0.025 mm)

Answer

0.005 inch (0.127 mm)

Answer

0.010 inch (0.254 mm)

Question 4

What is 'soft foot' in the context of machinery installation?

Accepted Answer

A condition where one or more machine feet do not make full contact with the baseplate when hold-down bolts are tightened

Answer

A machine foot made of rubber to absorb vibration

Answer

The flexing of a shaft coupling under load

Answer

Looseness in the foundation anchor bolts

Question 5

Which alignment method mounts two dial indicators on the coupling hub of each machine and measures runout as the shafts are rotated together?

Accepted Answer

Reverse indicator method

Answer

Rim and face method

Answer

Laser tracker method

Answer

Straightedge and feeler gauge method

Question 6

Thermal growth must be accounted for during precision shaft alignment because:

Accepted Answer

Machinery expands when it reaches operating temperature, shifting the shaft centerlines from their cold-aligned positions

Answer

It changes the coupling stiffness during operation

Answer

Thermal growth only affects the baseplate, not the machine shafts

Answer

It reduces vibration amplitude at running speed

Question 7

What is the primary purpose of shims during machinery installation?

Accepted Answer

To adjust the vertical position of machine feet to achieve correct shaft alignment

Answer

To absorb vibration between the machine and baseplate

Answer

To prevent corrosion between the machine foot and baseplate

Answer

To distribute the weight of the machine evenly across the baseplate