EIAT Gears, Pulleys, and Levers 3 — Questions and Answers
Question 1: A worm gear system uses a worm with 1 thread meshing with a worm wheel of 40 teeth. What is the gear ratio?
- 1:1
- 1:20
- 1:40 (Correct answer)
- 40:1
Correct answer: 1:40
The gear ratio of a worm drive equals the number of teeth on the worm wheel divided by the number of worm threads: 40 ÷ 1 = 40:1 reduction.
Question 2: In an elevator hoist system, a sheave acts as a:
- Fixed gear
- Pulley wheel grooved for rope or cable (Correct answer)
- Lever arm
- Counterweight
Correct answer: Pulley wheel grooved for rope or cable
A sheave is a grooved wheel (pulley) designed to guide and support a rope, cable, or belt in elevator systems.
Question 3: If a lever arm is 6 feet long and the fulcrum is 1.5 feet from the load end, what is the mechanical advantage?
- 3 (Correct answer)
- 4
- 6
- 9
Correct answer: 3
MA = effort arm ÷ load arm = 4.5 ÷ 1.5 = 3.
Question 4: Which type of gear converts rotational motion between shafts that are at right angles to each other?
- Spur gear
- Helical gear
- Bevel gear (Correct answer)
- Rack and pinion
Correct answer: Bevel gear
Bevel gears are specifically designed to transmit power between intersecting shafts, typically at 90-degree angles.
Question 5: A movable pulley attached to the load effectively:
- Doubles the required effort
- Halves the required effort (Correct answer)
- Triples the required effort
- Has no effect on effort
Correct answer: Halves the required effort
A movable pulley distributes the load across two rope segments, so only half the load force is required as effort.
Question 6: Helical gears are preferred over spur gears in many applications because they:
- Are cheaper to manufacture
- Run more quietly and carry higher loads (Correct answer)
- Always increase speed
- Only work on parallel shafts
Correct answer: Run more quietly and carry higher loads
Helical gears have angled teeth that engage gradually, resulting in quieter operation and greater load capacity than spur gears.
Question 7: A third-class lever has the effort applied between the fulcrum and the load. This arrangement always:
- Multiplies force
- Multiplies distance/speed of movement (Correct answer)
- Reduces the load on the fulcrum
- Creates a mechanical advantage greater than 1
Correct answer: Multiplies distance/speed of movement
Third-class levers sacrifice force (MA < 1) but amplify the distance and speed of the load's movement.
EIAT Gears, Pulleys, and Levers 3
A worm gear system uses a worm with 1 thread meshing with a worm wheel of 40 teeth.
What is the gear ratio?