Replacing Traction Ropes with a Different Diameter
A 12-story apartment building has a geared traction elevator with six 5/8-inch suspension ropes. During maintenance, the mechanic finds broken wires in two ropes and severe wear in the others. The building's regular supplier can deliver only 9/16-inch rope on short notice. The contractor proposes to replace all six ropes with 9/16-inch rope and to re-machine the traction sheave to match the smaller rope. The owner is told this is a 'maintenance replacement' because the number of ropes and the car weight are unchanged, and the elevator can remain in service during the work. The contractor says the smaller rope has a higher strength rating per rope, so safety is not reduced. The building has one elevator, and residents are asking when it will be back.
1. Is replacing the ropes with a different diameter and re-machining the sheave a repair or an alteration? What factors control?
Read the worked answer
This is an alteration, not a like-kind repair. Changing the rope diameter changes the rope-to-sheave fit, the groove pressure, the traction characteristics, and the loading on the sheave and machine. Re-machining the sheave changes the driving-machine interface. The number of ropes and the car weight being unchanged do not make the work maintenance, because the design of the suspension and traction system is being changed. The contractor's higher strength-per-rope claim is incomplete: the mechanic must consider sheave groove pressure, rope wear, traction, and the manufacturer's or engineer's approval. A permit and approved design are required before the work begins.
2. What should the mechanic do about the two ropes with broken wires before the alteration is approved?
Read the worked answer
The mechanic must apply the rope replacement criteria in the adopted code and the manufacturer's instructions, not wait for the alteration. If the broken wires or wear exceed the replacement criteria, the elevator must be removed from service until the ropes are replaced. The mechanic should document the rope condition, notify the owner in writing, and, if the owner refuses to remove the unit from service, notify the AHJ. A pending alteration does not authorize continued operation with defective suspension ropes. Because this is a single-elevator building, the mechanic should explain the risk clearly and arrange an expedited repair or approved alteration.
3. If the alteration is approved, what acceptance tests and documentation should be required?
Read the worked answer
After installation, the AHJ should require an acceptance inspection and tests that cover rope tension equalization, traction and braking, sheave alignment and groove condition, and clearances. Documentation should include rope certificates, sheave machining records, the manufacturer's or engineer's approval, and revised maintenance instructions. The certificate of inspection must be updated before the elevator is returned to service. The mechanic should also verify that the governor and safety device still operate correctly with the changed rope diameter and that the rope guards and clearances are adequate.