CPM Mechanical Power Transmission 2

Question 1

When checking V-belt tension by the force-deflection method, what deflection is the common rule of thumb?

Accepted Answer

1/64 inch per inch of span

Answer

The standard guideline is 1/64 inch of deflection for every inch of belt span length.

Question 2

Why must V-belts on a multi-groove sheave drive be replaced as a matched set?

Accepted Answer

Belts of equal length share the load equally

Answer

Unequal lengths make the tighter belts carry most of the load, causing premature failure.

Question 3

Standard industrial roller chain is generally replaced when elongation from wear reaches approximately what percentage?

Accepted Answer

3%

Answer

Most manufacturers recommend replacement at about 3% elongation, or less for precise or high-speed drives.

Question 4

For a horizontal roller chain drive, recommended slack-side sag is typically about what percent of the center distance?

Accepted Answer

2% to 3%

Answer

A sag of about 2–3% of center distance prevents both over-tensioning and chain whip.

Question 5

A V-belt drive squeals loudly each time the motor starts. What is the most likely cause?

Accepted Answer

Insufficient belt tension causing slip

Answer

Startup squeal is typically belt slip from low tension under the high starting torque.

CPM - Certified Plant Mechanic Practice Test