EIAT Gears, Pulleys, and Levers 4 — Questions and Answers
Question 1: In a block and tackle system with 3 movable pulleys, how many rope segments support the load?
- 3
- 4
- 6 (Correct answer)
- 8
Correct answer: 6
Each movable pulley adds 2 rope segments, so 3 movable pulleys provide 6 supporting rope segments and a MA of 6.
Question 2: 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:
- 100 RPM (Correct answer)
- 150 RPM
- 2500 RPM
- 375 RPM
Correct answer: 100 RPM
Output RPM = Input RPM × (driver teeth ÷ driven teeth) = 500 × (15 ÷ 75) = 100 RPM.
Question 3: What is the purpose of a counterweight in an elevator system?
- To increase the cable tension
- To reduce the motor load by balancing the car weight (Correct answer)
- To add friction to the braking system
- To increase the mechanical advantage of the pulleys
Correct 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.
Question 4: When a small gear drives a large gear, the output shaft produces:
- Higher speed and lower torque
- Lower speed and higher torque (Correct answer)
- Same speed and same torque
- Higher speed and higher torque
Correct answer: Lower speed and higher torque
Driving a larger gear results in a speed decrease and a proportional torque increase at the output shaft.
Question 5: A rack and pinion gear system converts:
- Rotary motion to linear motion (Correct answer)
- Linear motion to rotary motion only
- Rotary motion to rotary motion
- Torque to electrical energy
Correct 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.
Question 6: If you apply 50 lb of effort to a lever and the mechanical advantage is 5, what load can you lift?
- 10 lb
- 55 lb
- 250 lb (Correct answer)
- 500 lb
Correct answer: 250 lb
Load = Effort × Mechanical Advantage = 50 × 5 = 250 lb.
Question 7: In elevator machinery, gears are lubricated primarily to:
- Increase gear ratio
- Reduce friction, heat, and wear (Correct answer)
- Increase backlash
- Slow down gear rotation
Correct answer: Reduce friction, heat, and wear
Lubrication creates a film between gear teeth that reduces friction, dissipates heat, and extends gear service life.
EIAT Gears, Pulleys, and Levers 4
In a block and tackle system with 3 movable pulleys, how many rope segments support the load?