New Traction Elevator with Uneven Rope Tension

The readings are not acceptable as a matched set. The average of the six readings is about 176 lb; rope 6 at 125 lb is roughly 29% below the average and well outside the usual manufacturer tolerance of about 10%. Ropes 1 through 5 are within a few percent of each other, so the problem is concentrated on rope 6. Tightening rope 6 and running the car for a week is not a proper equalization procedure. Before adjustment, the mechanic should inspect rope 6 for twist, kinks, broken wires, wrong lay, and incorrect seating in the equalizer or dead-end hitch. The equalizer springs and nuts should be adjusted in small increments per the manufacturer's instructions, with the car at the same position for each reading, and the readings should be repeated at several car positions. If rope 6 is damaged or mismatched, it should be replaced as part of a matched rope set rather than over-tightened.

Rope tension is only one possible cause. The mechanic should check car and counterweight guide shoe clearances against the manufacturer's values; 1/8 in. may be excessive for that guide shoe, and the shiny rail pattern suggests misalignment or improper shoe contact. The guide rails should be checked for plumb, joint alignment, fishplate tightness, and smoothness. The sheave should be checked for alignment with the rope falls, and the ropes should be checked for twist or improper reeving. The counterweight should be balanced to the car weight plus approximately 40% to 50% of rated load; an incorrect balance can cause motor current imbalance and sway. The mechanic should also verify that the car and counterweight are not rubbing on guides, that the rope equalizer is free, and that the machine is shimmed and aligned. All readings should be taken with the car at a consistent location and before turnover.

A rope should be replaced when inspection reveals conditions that retirement criteria address, such as broken wires in a concentrated area, severe corrosion, kinks, birdcaging, crushed or jammed strands, marked diameter reduction, or abnormal elongation. A rope that is mismatched in lay or construction, or that has been damaged by a sheave or hitch, should not be corrected by tension adjustment alone. For traction elevators, ropes are normally replaced as a matched set so that load sharing remains within tolerance. The mechanic should follow the adopted A17.6 rope retirement criteria and the rope manufacturer's instructions, document the measurements, and not rely on 'seating' the ropes to cure a defect. If rope 6 is undamaged but simply misadjusted, equalization may be acceptable; if it shows any retirement condition, replacement is required before the elevator is turned over.