Gears, Pulleys, and Levers Flashcards

In a block and tackle system with 3 movable pulleys, how many rope segments support the load?

Answer: 6

Each movable pulley adds 2 rope segments, so 3 movable pulleys provide 6 supporting rope segments and a MA of 6.

A pinion gear with 15 teeth drives a ring gear with 75 teeth. If the pinion turns at 500 RPM, the ring gear turns at:

Answer: 100 RPM

Output RPM = Input RPM × (driver teeth ÷ driven teeth) = 500 × (15 ÷ 75) = 100 RPM.

What is the purpose of a counterweight in an elevator system?

Answer: To reduce the motor load by balancing the car weight

A counterweight approximately equals the car weight plus half the rated load, reducing the net force the motor must overcome.

When a small gear drives a large gear, the output shaft produces:

Answer: Lower speed and higher torque

Driving a larger gear results in a speed decrease and a proportional torque increase at the output shaft.

A rack and pinion gear system converts:

Answer: Rotary motion to linear motion

A rack and pinion converts the rotational motion of the pinion into the linear (straight-line) motion of the rack.

If you apply 50 lb of effort to a lever and the mechanical advantage is 5, what load can you lift?

Answer: 250 lb

Load = Effort × Mechanical Advantage = 50 × 5 = 250 lb.

In elevator machinery, gears are lubricated primarily to:

Answer: Reduce friction, heat, and wear

Lubrication creates a film between gear teeth that reduces friction, dissipates heat, and extends gear service life.