Why escalator handrails heat up

A handrail that is warm after a shift is doing its job. A handrail that is too hot to hold comfortably for a few seconds is telling you that something is rubbing, and the heat is the energy of that rub. The useful question is not "is it hot" but "where is it hot". Start with a baseline, because "hot" is relative. On a healthy unit the handrail runs a few degrees above ambient, and the difference is roughly the same on both sides. Run the escalator loaded for fifteen or twenty minutes, then measure with an infrared thermometer at four points: the handrail just after it leaves the drive wheel, at each newel wheel entry, and at the handrail inlet at the bottom landing. Write the ambient temperature down too. A handrail at 45 degrees in a 30 degree lobby is a different situation from one at 45 degrees in an 18 degree shaft. Now the causes, roughly in the order they turn up. Tension. A handrail that is too tight is being stretched over every guide and every newel wheel, and the friction at each of them adds up along the whole loop. Check the tension carriage position first: if it is near the end of its travel, the tension is wrong, and it is often wrong because someone tightened it to stop a slip that was actually caused by a glazed drive wheel. The guide system. Bent or misaligned guides, a guide bracket that has moved, or guide joints that do not line up will drag on the inner surface and produce a hot spot rather than general warmth. This is where the thermometer earns its keep: a hot spot at one point along the incline, with the rest of the loop normal, is a guide problem, not a tension problem. The drive wheel. The handrail is driven by friction between the drive wheel and the inner surface. If the pressure roller is set too hard, the belt is squeezed and the rubber heats. If the wheel is glazed, worn, or contaminated with oil, it slips, and a slipping wheel generates heat in a much smaller area. Both look like "the handrail is hot near the machine", and they need different fixes. Tracking. A drive wheel that contacts the handrail off center, or a handrail that is running to one side of the wheel, heats one edge of the belt. Look at the wear pattern on the inner surface: a bright stripe at the edge instead of an even band across the middle means the belt is not tracking, and the cause is usually a guide roller or the tension carriage alignment, not the wheel itself. The inlet and return guides. These are small parts in a dirty place, and they wear. A worn inlet guide can pinch the handrail, and the heat shows up right at the entry. The bearing. A newel wheel bearing that is dry or failing will heat the handrail locally, and it will also make noise. Put a hand on the newel housing after a run; if one end is noticeably warmer than the other, that bearing is suspect. The belt itself. An old handrail hardens, and a hard belt does not flex cleanly around the newel wheels. It also grips the drive wheel less well, so it slips and heats. If the handrail is more than eight or ten years old and has cracks on the inner surface, the heat is a symptom of the belt, and adjusting anything else is a waste of a visit. The fix that makes it worse is loosening the tension. It stops the stretch-related heat for a week, then the belt slips on the drive wheel, and slip generates more heat than tension ever did, in a smaller area, right where the splice passes. Set the tension to the manufacturer's figure and leave it there. What heat actually damages: the rubber, first at the splice and at the newel bends. A handrail that has been running hot for months will show fine cracks at the splice long before its time, and the splice is the part that fails dangerously. So a hot handrail is not a comfort issue, it is a life issue, and the measurement takes ten minutes.