Plant Operator Selection System Mechanical Concepts Flashcards

A compound gear train has a driving gear with 10 teeth meshed with an intermediate gear of 50 teeth. The intermediate gear is on the same shaft as a 10-tooth gear driving a final gear with 40 teeth. What is the overall gear ratio (input to output)?

Answer: 20:1

Overall ratio = (50/10) × (40/10) = 5 × 4 = 20:1, meaning the output shaft turns once for every 20 input turns.

Which type of bearing is specifically designed to handle axial (thrust) loads along a shaft's axis?

Answer: Thrust bearing

Thrust bearings are engineered to support loads parallel to the shaft axis, unlike radial bearings that handle perpendicular loads.

A manometer reads 25 inches of water column. Approximately how many PSI does this represent?

Answer: 0.9 PSI

Water column converts at 27.7 inches H₂O per PSI, so 25 ÷ 27.7 ≈ 0.9 PSI.

In a steam system, which device removes condensed water (condensate) from the steam lines without allowing steam to escape?

Answer: Steam trap

A steam trap automatically drains condensate while keeping steam in the system, preventing water hammer and efficiency loss.

A centrifugal pump is running but producing no flow. Which condition is MOST likely the cause?

Answer: The pump is air-bound (cavitating on air)

If a centrifugal pump is air-bound, it cannot create suction because air does not produce enough centrifugal force to move liquid.

What is the mechanical advantage of a single fixed pulley used to lift a load?

Answer: 1

A single fixed pulley only changes the direction of force; the mechanical advantage is 1 because you still pull with the full weight of the load.

Heat transfer that occurs through direct physical contact between two objects is called:

Answer: Conduction

Conduction is heat transfer through direct contact, as heat energy moves from molecule to molecule within or between materials.