Mechanical Aptitude Flashcards

What does the term 'mechanical advantage' mean in the context of simple machines?

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.

An elevator rope has a 7×19 wire rope construction. What does '19' refer to?

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.

Which of the following best describes the function of a brake on a gearless traction elevator?

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.

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?

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.

Which type of thread provides the greatest mechanical advantage for converting rotary motion to linear motion, commonly used in elevator screw-drive systems?

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.

A cam mechanism converts:

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.

If a Class 3 lever has the effort applied between the fulcrum and the load, it will always:

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.