Mechanical Power Transmission Flashcards

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

Answer: 1/64 inch per inch of span

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

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

Answer: Belts of equal length share the load equally

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

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

Answer: 3%

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

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

Answer: 2% to 3%

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

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

Answer: Insufficient belt tension causing slip

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

What is the main advantage of a synchronous (timing) belt over a standard V-belt?

Answer: It maintains an exact speed ratio with no slip

Teeth mesh positively with the pulley grooves, so the speed ratio stays exact.

During inspection, sprocket teeth look hooked and pointed. What is the correct action?

Answer: Replace both the sprocket and the chain

Hooked teeth show advanced wear, and a worn sprocket rapidly destroys a new chain, so both are replaced.