CET Roping & Counterweight Systems Flashcards
6 cards from real CET practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 CET Roping & Counterweight Systems flashcards as text
What is the standard minimum number of hoist ropes required for a traction elevator under ASME A17.1?
Answer: 3
ASME A17.1 requires a minimum of three hoist ropes for traction elevators to provide redundancy and safety against rope failure.
What is the purpose of the counterweight in a traction elevator system?
Answer: Offsets the weight of the car and a portion of the rated load to reduce motor energy consumption
The counterweight balances the car weight plus approximately 40–50% of the rated load, significantly reducing the energy required to drive the elevator.
What percentage of rated load is typically added to the car weight when calculating counterweight mass?
Answer: 40–50%
Counterweights are typically set to equal the car weight plus 40–50% of the rated capacity to minimize motor loading in both directions.
In a 1:1 roping arrangement, how does the rope travel distance compare to car travel distance?
Answer: Rope and car travel the same distance
In a 1:1 roping arrangement, the hoist rope and the car move the same distance for every rotation of the drive sheave.
What is the advantage of a 2:1 roping arrangement compared to a 1:1 arrangement?
Answer: Greater mechanical advantage allowing a smaller motor to lift heavier loads
A 2:1 roping arrangement provides mechanical advantage, effectively doubling the lifting force of the motor at the cost of half the car speed.
What is the minimum design factor (safety factor) required for elevator hoist ropes under ASME A17.1?
Answer: 7.6
ASME A17.1 requires a minimum design factor of 7.6:1 (breaking strength to working load) for elevator wire rope hoist ropes in normal service.