EIAT Mechanical Aptitude 4 — Questions and Answers
Question 1: What does the term 'mechanical advantage' mean in the context of simple machines?
- The speed at which a machine operates
- The ratio of output force to input force (Correct answer)
- The efficiency percentage of a machine
- The total weight a machine can support
Correct answer: The ratio of output force to input force
Mechanical advantage is the ratio of the output force produced by a machine to the input force applied to it.
Question 2: An elevator rope has a 7×19 wire rope construction. What does '19' refer to?
- The rope diameter in millimeters
- The number of wires in each strand (Correct answer)
- The minimum breaking strength in tons
- The total number of strands
Correct answer: The number of wires in each strand
In a 7×19 designation, 7 is the number of strands and 19 is the number of individual wires within each strand.
Question 3: Which of the following best describes the function of a brake on a gearless traction elevator?
- Slow the motor between floors
- Hold the car stationary when the motor is de-energized (Correct answer)
- Limit door closing speed
- Reduce electrical current during startup
Correct answer: Hold the car stationary when the motor is de-energized
The electromagnetic brake engages when power is removed from the motor to hold the car and prevent drift at a landing.
Question 4: In a hydraulic system, a pressure relief valve is set to open at 1,200 psi. What happens when system pressure reaches 1,500 psi?
- The pump increases output
- The valve opens and bypasses fluid back to the reservoir (Correct answer)
- The cylinder extends faster
- The system shuts down completely
Correct answer: The valve opens and bypasses fluid back to the reservoir
A pressure relief valve opens to divert excess fluid back to the reservoir, protecting the system from overpressure damage.
Question 5: Which type of thread provides the greatest mechanical advantage for converting rotary motion to linear motion, commonly used in elevator screw-drive systems?
- V-thread (standard)
- Acme thread (Correct answer)
- Buttress thread
- Fine-pitch thread
Correct answer: Acme thread
Acme threads have a trapezoidal profile that provides high efficiency and load-bearing capacity for power transmission applications like screw-drive elevators.
Question 6: A cam mechanism converts:
- Linear motion to hydraulic pressure
- Rotary motion into a specific pattern of linear or oscillating motion (Correct answer)
- Electrical energy to mechanical torque
- Gear speed to torque
Correct answer: Rotary motion into a specific pattern of linear or oscillating motion
A cam converts the uniform rotation of a shaft into a prescribed linear or rocking motion in a follower, based on the cam's profile shape.
Question 7: If a Class 3 lever has the effort applied between the fulcrum and the load, it will always:
- Multiply force but reduce distance
- Multiply distance (speed) but require more effort force than the load (Correct answer)
- Balance the load with equal effort
- Self-lock when released
Correct answer: Multiply distance (speed) but require more effort force than the load
Class 3 levers always have a mechanical advantage less than 1, requiring more effort than the load but gaining speed or range of motion.
EIAT Mechanical Aptitude 4
What does the term 'mechanical advantage' mean in the context of simple machines?