CET Traction Elevator Mechanics 2

Question 1

What is the primary function of the deflector sheave in a traction elevator?

Accepted Answer

To redirect the hoist ropes to a different angle

Answer

A deflector sheave redirects the hoist ropes so they hang vertically from the drive sheave to the car and counterweight.

Question 2

In a 2:1 roping arrangement, how does the car speed compare to the rope speed at the drive sheave?

Accepted Answer

Car speed is half the rope speed

Answer

In 2:1 roping, the car moves at half the speed of the rope because the mechanical advantage doubles the lifting force while halving the speed.

Question 3

What causes 'creep' in elevator hoist ropes on a traction sheave?

Accepted Answer

Differential elongation of ropes under varying loads

Answer

Creep occurs when ropes stretch unequally under load changes, causing slight slippage relative to the sheave groove.

Question 4

Which type of hoist rope construction is most commonly used in modern traction elevators?

Accepted Answer

6x19 independent wire rope core (IWRC)

Answer

6x19 IWRC ropes are standard because they offer a good balance of flexibility, strength, and fatigue resistance for elevator service.

Question 5

What is the minimum number of hoist ropes required by ASME A17.1 for a traction elevator?

Accepted Answer

Two

Answer

ASME A17.1 requires a minimum of two hoist ropes for traction elevators to ensure redundancy in case of one rope failure.

(CET) Certified Elevator Technician Practice Test