Mechanical Aptitude Flashcards

A counterweight in an elevator system is used primarily to:

Answer: Reduce the load on the hoisting motor

A counterweight balances most of the cab's weight, significantly reducing the energy and motor force needed to lift or lower the car.

If a gear with 40 teeth meshes with a gear with 10 teeth, and the smaller gear rotates at 200 RPM, how fast does the larger gear rotate?

Answer: 50 RPM

Gear ratio is inversely proportional to tooth count; the larger gear rotates at 200 × (10/40) = 50 RPM.

Which type of bearing is best suited to handle combined radial and axial (thrust) loads simultaneously?

Answer: Tapered roller bearing

Tapered roller bearings are specifically designed to support both radial and axial thrust loads at the same time.

A hydraulic elevator uses fluid pressure to lift the cab. If the piston area is 10 in² and the system pressure is 500 psi, what is the lifting force?

Answer: 5,000 lb

Force equals pressure multiplied by area: 500 psi × 10 in² = 5,000 lb of lifting force.

What is the purpose of a safety governor on a traction elevator?

Answer: Detect and respond to overspeed by triggering the safety device

The governor monitors car speed and, if overspeed is detected, mechanically trips the car safety device to stop the cab.

When two pulleys are connected by a belt and the driving pulley has a 6-inch diameter while the driven pulley has a 3-inch diameter, the driven pulley will:

Answer: Rotate at twice the speed of the driver

The driven pulley with half the diameter rotates twice as fast as the driving pulley due to the inverse speed ratio.

Which class of lever is demonstrated when a person uses a crowbar with the fulcrum between the effort and the load?

Answer: Class 1

A Class 1 lever has the fulcrum positioned between the effort force and the load, like a seesaw or crowbar in typical use.