What causes the escalator handrail to run unstably?
What causes the escalator handrail to run unstably? Worn drive wheel, deformed handrail guide rail,poor lubricated or wrong installation may cause handrail belts run unstably.
Sep 16,2026
Escalator handrail‑belt stability strongly affects passenger safety, riding comfort and equipment service life. When the handrail belt runs slower or faster than the steps, riders may lose balance and fall. Serious injury accidents have happened in shopping‑malls because of large speed differences between handrail belts and steps, especially harming elderly people and children.
An escalator handrail‑belt system mainly includes three parts: the handrail belt, the handrail drive unit and the tension‑adjusting device. Its core function is to provide hand support moving in sync with the steps, so passengers can hold on and keep body balance.
There are two common handrail‑belt cross‑section types: C‑shape for low‑rise escalators and V‑shape for high‑rise escalators. Friction‑wheel drive is the most widely‑used drive structure. Friction between the friction wheel and the belt pushes the handrail to move. As belts stretch after long‑time service, tension devices keep proper friction force for normal operation.
Standards require:
1. According to GB 16899‑2011, handrail‑belt speed shall be 0 ~ +2 % faster than step speed.
2. TSG T7001‑2023 requires the escalator shall stop automatically if the speed deviation exceeds 15 % and lasts 5‑15 seconds.
Main Causes of Unstable Handrail‑Belt Movement
1/ Worn / deformed mechanical parts, poor lubrication or wrong installation
- Worn drive wheel: Rubber or polyurethane wheel surface wears unevenly, forming dents. Friction drops, the belt slips and speed fluctuates. Periodic vertical vibration may occur.
- Deformed handrail guide rail: Long‑term pressure and aging deform or crack the rail. The handrail gets side resistance and swings sideways. Misaligned rail joints can make the belt jump, especially on curved transition sections.
- Poor‑lubricated support rollers and worn turning wheels: Lack of lubrication increases rolling resistance. Worn turning wheels create high‑frequency vibration. Stuck single rollers cause jerky, stop‑and‑go belt movement.
2/ Improper adjustment of tension device
- Too little tension: Dust and rust block the tension mechanism. Insufficient pressing force makes the belt slip, shake and drop behind the steps.
- Too much tension: Excess tension speeds up drive‑wheel wear and creates horizontal shaking. In cold weather, belt shrinkage may go beyond the tension‑system compensation range.
3/ Faults of handrail‑belt speed‑monitoring system
Encoders calculate belt speed from shaft rotation signals. Failures come from three aspects:
- Dust, oil or moisture contaminate optical sensors and distort signals.
- Worn encoder bearings cause shaft wobble and lower measuring accuracy.
- Mis‑aligned installation of encoders leads to signal shaking or signal loss.
4/ Inadequate routine maintenance
• Missing lubrication or wrong lubricant increases friction or damages rubber material.
• Hard debris, sticky drinks and sugar residues left on guide rails scratch the belt and trigger intermittent slipping.
• Maintenance teams skip regular speed‑synchronism checks between handrail belts and steps.
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