Escalator Annual Inspection: Skirt Clearance, Broken Comb Teeth, and Handrail Speed
You are performing an annual inspection on a 1995 escalator serving a transit station. The escalator has a 20-foot rise, 32-inch step width, and a nominal step speed of 0.50 m/s. During the ride and pit inspection you find: left-side step-to-skirt clearance of 6 mm at one location about midway up the incline, while the rest of the left side and the right side measure about 3 mm. The comb segment at the lower landing has four broken teeth out of twenty. The handrail speed measured on the left side is 0.52 m/s while the step speed is 0.50 m/s. The brake stops the unloaded escalator, but you have not yet performed the loaded brake test. The skirt-panel switches and comb switches operate when tested by hand. The station manager says the escalator carries about 8,000 people per day and asks whether the broken comb teeth can wait until the next maintenance visit.
1. Evaluate each finding. Which conditions require removal from service before the station opens?
Read the worked answer
The 6 mm skirt clearance is not a normal wear item. Step-to-skirt clearance is a pinch and entrapment hazard, and a single location that is roughly double the rest of the side indicates a local deflection, a damaged skirt panel, or a step that is out of alignment. It should be corrected before passenger service, because the switch may not detect a gradual clothing or shoe entrapment. The four broken comb teeth are also a removal-from-service condition in practical judgment: broken teeth create sharp edges and gaps at the comb plate where shoes and clothing can catch. The handrail speed difference is 0.52 versus 0.50 m/s, about 4 percent fast; handrail speed must track step speed within the code tolerance, and a 4 percent deviation is outside the normal tolerance and can cause a passenger to lose balance. It needs adjustment and retest. The operating switches are not a pass by themselves; they only show the switch trips when moved by hand. The unloaded brake stop is not enough to clear the escalator either. The skirt clearance, comb teeth, and handrail speed should be corrected before opening.
2. What tests and documentation should be completed before you sign the inspection report?
Read the worked answer
After the skirt panel, step alignment, comb segment, and handrail drive are corrected, retest the skirt-panel switches and comb switches at their actual trip points, not just by hand at the switch body. Measure step-to-skirt clearance at multiple points on both sides and record the values. Measure handrail speed and step speed together and record the ratio. Perform the brake test required for the escalator, including the loaded condition specified by the applicable inspection procedure, and record stopping distance, load, and direction. Check the step chain and handrail drive for the cause of the speed change, because a fast handrail may indicate a worn drive or a recent adjustment. Document each deficiency, correction, and retest value on the inspection report, and note the date and the personnel who made the corrections. If any value remains outside tolerance, do not sign a passing report; leave the escalator out of service and notify the station manager and the Georgia Elevator Division through the required process. The daily passenger volume is a reason for stricter judgment, not a reason to defer.