QEI Traction Drive Systems and Wire Rope 1 — Questions and Answers
Question 1: What is the minimum number of wire ropes or chains required for a traction elevator under ASME A17.1?
- One
- Two (Correct answer)
- Three
- Four
Correct answer: Two
ASME A17.1 requires a minimum of two wire ropes or chains for traction elevators to provide redundancy.
Question 2: Which type of traction machine uses a worm gear to transmit power from the motor to the sheave?
- Gearless traction machine
- Geared traction machine (Correct answer)
- Hydraulic drive unit
- Linear induction motor
Correct 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.
Question 3: What condition requires the immediate removal of a wire rope from service according to ASME A17.1?
- Minor surface rust
- Six or more broken wires in one rope lay (Correct answer)
- One broken wire in the entire rope
- Slight kinking near the hitch
Correct 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.
Question 4: What is the purpose of the secondary sheave (deflector sheave) in a traction elevator roping system?
- To provide additional traction
- To redirect the ropes to achieve the correct geometry between the car and counterweight (Correct answer)
- To tension the governor rope
- To absorb vibration from the drive motor
Correct 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.
Question 5: In a 2:1 roping arrangement, how does the car speed compare to the rope speed at the drive sheave?
- Car speed equals rope speed
- Car speed is twice the rope speed
- Car speed is half the rope speed (Correct answer)
- Car speed is four times the rope speed
Correct 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.
Question 6: What is the function of the rope equalizer in a traction elevator?
- To measure rope tension electronically
- To distribute load evenly among all hoist ropes (Correct answer)
- To prevent rope oscillation during travel
- To anchor the rope to the crosshead
Correct 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.
QEI Traction Drive Systems and Wire Rope 1
What is the minimum number of wire ropes or chains required for a traction elevator under ASME A17.1?