EIAT Mechanical Aptitude 5 — Questions and Answers
Question 1: What is the primary purpose of lubrication in a mechanical system?
- Increase friction between surfaces
- Reduce friction, prevent wear, and dissipate heat between moving parts (Correct answer)
- Increase the load-bearing capacity of fasteners
- Conduct electrical current between components
Correct answer: Reduce friction, prevent wear, and dissipate heat between moving parts
Lubrication creates a film between moving surfaces that reduces friction, minimizes wear, and carries away heat generated by contact.
Question 2: An inclined plane is 12 feet long and raises a load 3 feet high. Ignoring friction, what is the mechanical advantage?
- 3
- 4 (Correct answer)
- 36
- 0.25
Correct answer: 4
Mechanical advantage of an inclined plane equals the length divided by the height: 12 ÷ 3 = 4.
Question 3: Which of the following would increase the tension in a drive belt to prevent slipping?
- Increasing pulley diameter
- Moving the pulleys closer together
- Adding a tensioner pulley or increasing center distance (Correct answer)
- Reducing motor speed
Correct answer: Adding a tensioner pulley or increasing center distance
A tensioner pulley or increasing center distance adds slack-side tension to the belt, improving the grip and preventing slippage.
Question 4: A solid steel shaft will resist twisting (torsion) better than a hollow shaft of the same outer diameter because:
- Steel is always stronger when solid
- The statement is false — a hollow shaft with the same outer diameter often resists torsion nearly as well per unit weight (Correct answer)
- Hollow shafts always crack under torque
- Solid shafts have lower rotational inertia
Correct answer: The statement is false — a hollow shaft with the same outer diameter often resists torsion nearly as well per unit weight
A hollow shaft of equal outer diameter has nearly the same torsional rigidity as a solid one because material near the center contributes little to torsional resistance.
Question 5: When inspecting an elevator machine room, you notice oil leaking from a shaft seal. The FIRST corrective action should be:
- Add more oil and continue operation
- Clean up the oil and identify the leak source before taking further action (Correct answer)
- Immediately shut down the elevator permanently
- Replace the entire gearbox
Correct answer: Clean up the oil and identify the leak source before taking further action
The correct first step is to clean the area and identify the leak source to determine severity before deciding on the repair approach.
Question 6: In a roped hydraulic elevator, what is the purpose of the roping?
- To provide emergency stopping power
- To multiply the travel distance of the plunger using a mechanical advantage (Correct answer)
- To connect the cab to the governor
- To support the counterweight
Correct answer: To multiply the travel distance of the plunger using a mechanical advantage
Roping in a roped hydraulic elevator allows the cab to travel farther than the cylinder stroke by using a pulley-based mechanical advantage ratio.
Question 7: What does a torque wrench measure?
- The speed of bolt rotation
- The rotational force applied to a fastener (Correct answer)
- The thread pitch of a bolt
- The tensile strength of a nut
Correct answer: The rotational force applied to a fastener
A torque wrench measures the rotational force (torque) being applied to a fastener to ensure it is tightened to the specified value.
EIAT Mechanical Aptitude 5
What is the primary purpose of lubrication in a mechanical system?