EIAT Mechanical Aptitude 3 — Questions and Answers
Question 1: A wire rope used in elevator hoisting is inspected and found to have broken wires. According to general safety standards, a rope should be replaced if it has how many broken wires in one lay length?
- 2 or more
- 6 or more (Correct answer)
- 10 or more
- 20 or more
Correct answer: 6 or more
Industry standards typically require replacement of hoist ropes when 6 or more broken wires are found in one rope lay length.
Question 2: In a block and tackle system using 4 rope segments supporting the load, a 400 lb load requires approximately how much pulling force (ignoring friction)?
- 1,600 lb
- 400 lb
- 200 lb
- 100 lb (Correct answer)
Correct answer: 100 lb
With 4 supporting rope segments, the mechanical advantage is 4, so the effort force is 400 ÷ 4 = 100 lb.
Question 3: What is the function of a worm gear drive in elevator machinery?
- Increase speed with low torque
- Provide high speed reduction and self-locking capability (Correct answer)
- Convert hydraulic pressure to rotational motion
- Switch direction of electrical current
Correct answer: Provide high speed reduction and self-locking capability
Worm gear drives achieve large speed reductions in a compact package and are often self-locking, preventing back-driving under load.
Question 4: If a spring is compressed by 3 inches with a force of 90 lb, what force is needed to compress it an additional 1 inch (to 4 inches total), assuming it follows Hooke's Law?
- 90 lb
- 30 lb
- 120 lb (Correct answer)
- 60 lb
Correct answer: 120 lb
The spring constant is 90 ÷ 3 = 30 lb/in, so 4 inches of compression requires 30 × 4 = 120 lb.
Question 5: A sheave (pulley wheel) in an elevator system with a worn groove will most likely cause:
- Faster rope travel
- Increased rope wear and possible slippage (Correct answer)
- Reduced motor load
- Better traction on the rope
Correct answer: Increased rope wear and possible slippage
Worn or mismatched grooves reduce the contact area between rope and sheave, accelerating rope wear and reducing traction.
Question 6: Which principle explains why fluid velocity increases when it flows through a narrower section of pipe?
- Pascal's Law
- Boyle's Law
- Bernoulli's Principle / Continuity equation (Correct answer)
- Newton's Third Law
Correct answer: Bernoulli's Principle / Continuity equation
The continuity equation (part of Bernoulli's Principle) states that fluid must speed up in a narrower cross-section to maintain constant flow rate.
Question 7: A technician notices that an elevator motor is running hot. Which of the following is the LEAST likely cause?
- Overloaded car beyond rated capacity
- Clogged motor ventilation
- Excessive number of starts per hour
- Counterweight properly balanced (Correct answer)
Correct answer: Counterweight properly balanced
A properly balanced counterweight reduces motor load and would not cause overheating — it is a normal, desirable operating condition.
EIAT Mechanical Aptitude 3
A wire rope used in elevator hoisting is inspected and found to have broken wires.
According to general safety standards, a rope should be replaced if it has how many broken wires in one lay length?