Traction Drive Systems and Wire Rope Flashcards

What is the minimum number of wire ropes or chains required for a traction elevator under ASME A17.1?

Answer: Two

ASME A17.1 requires a minimum of two wire ropes or chains for traction elevators to provide redundancy.

Which type of traction machine uses a worm gear to transmit power from the motor to the sheave?

Answer: Geared traction machine

Geared traction machines use a worm gear (or helical gear) between the motor and the drive sheave, typically used on low- to mid-rise elevators.

What condition requires the immediate removal of a wire rope from service according to ASME A17.1?

Answer: Six or more broken wires in one rope lay

ASME A17.1 mandates rope removal when six or more broken wires are found in one rope lay, indicating significant structural degradation.

What is the purpose of the secondary sheave (deflector sheave) in a traction elevator roping system?

Answer: To redirect the ropes to achieve the correct geometry between the car and counterweight

A deflector sheave changes the direction of the ropes so that the car and counterweight travel paths align properly within the hoistway.

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

Answer: Car speed is half the rope speed

In a 2:1 roping arrangement, mechanical advantage doubles the load capacity but the car moves at half the rope speed.

What is the function of the rope equalizer in a traction elevator?

Answer: To distribute load evenly among all hoist ropes

Rope equalizers (also called rope hitches or shackles with springs) distribute the load equally among all individual hoist ropes to prevent uneven wear.