Intermittent Escalator Stops with Step Rubbing

The escalator should be removed from service immediately and locked out. Intermittent stops with passengers aboard are a serious hazard, and the left-side step rubbing indicates that step-to-skirt clearance is compromised. Rubbing can lead to binding, step damage, skirt panel distortion, or a passenger trip and fall. The worn comb plates and chipped step cleat add additional catch points. The slower handrail and jerky brake are separate safety concerns that must be corrected before return to service. The manager's desire to keep the unit running through the holiday weekend does not override the hazard. The mechanic should place an out-of-service tag, notify the owner in writing, and explain that the unit cannot be operated until the cause of the intermittent stop and the rubbing condition is found and corrected.

The mechanic should use the tachometer to compare handrail speed with step speed at the same operating point. A handrail that is slower than the steps can be caused by a slipping handrail drive, a loose or elongated handrail, a misadjusted drive chain, worn drive rollers, or contamination on the drive wheel. The handrail drive chain adjustment made last month should be rechecked, along with handrail tension and elongation. For the brake, the mechanic should inspect the brake drum, lining, springs, linkage, and adjustment, then perform the required brake test with the specified load. A jerky stop may indicate oil or wear on the lining, a binding linkage, or incorrect spring tension. The intermittent stop itself may be electrical, a safety switch, a step-chain tension issue, or a skirt-panel contact; the mechanic should check fault codes and safety circuits, not just the mechanical items.

Before return to service, the mechanic must correct the step-to-skirt rubbing and verify clearance on both sides for the full length of the escalator. The worn comb plates and the chipped step must be replaced, and the step chain and handrail drive must be checked for elongation, tension, and alignment. Because no step-chain elongation gauge is available, the mechanic should use the manufacturer's measurement method or obtain the correct gauge; visual inspection alone is not sufficient. The handrail speed must be brought within the code and manufacturer tolerance relative to step speed, and the brake must be adjusted or repaired and tested under load. The intermittent stop must be diagnosed and corrected, including any safety-switch or controller fault. Only after these corrections and the required tests should the unit be returned to service; the holiday schedule is not a basis for deferring safety repairs.