CPM Mechanical Systems Installation & Repair 2

Question 1

When performing a reverse dial indicator alignment, a reading of +0.020 in. at the bottom of the coupling hub (zeroed at top) indicates what offset at that plane?

Accepted Answer

0.010 in.

Answer

Rim readings show twice the actual offset, so a 0.020 in. TIR equals 0.010 in. of offset.

Question 2

A soft foot condition on a motor is best detected by which method?

Accepted Answer

Loosening one hold-down bolt at a time while indicating foot movement

Answer

Loosening each bolt with an indicator on that foot reveals movement greater than about 0.002 in., which signals soft foot.

Question 3

What is the primary purpose of grouting a pump baseplate?

Accepted Answer

Provide a rigid, uniform load transfer between the baseplate and foundation

Answer

Grout fills voids to create full contact and rigid support, reducing vibration and distortion.

Question 4

When installing a bearing with an interference fit on a shaft using induction heating, what is the generally recommended maximum bearing temperature?

Accepted Answer

250°F (120°C)

Answer

Most manufacturers limit heating to about 250°F (120°C) to avoid altering the bearing steel's hardness.

Question 5

A centrifugal pump is making a crackling, gravel-like noise at the suction and showing reduced head. What is the most likely cause?

Accepted Answer

Cavitation due to insufficient NPSH available

Answer

Cavitation occurs when NPSHa falls below NPSHr, forming and collapsing vapor bubbles that sound like gravel.

CPM - Certified Plant Mechanic Practice Test

CPM - Certified Plant Mechanic Practice Test

CPM Mechanical Systems Installation & Repair 2