1. Safety Hazards Caused by Unstable Handrail Belt Operation

Speed asynchronization between escalator handrails and step treads is a major trigger of on-site safety incidents. In March 2024, an elderly passenger fell on a shopping mall escalator in Haikou, as the handrail speed deviation exceeded the national permissible limit. Similar accidents have caused passenger imbalance and injuries, fully demonstrating the severe safety hazards induced by unstable handrail operation.

As an essential safety component of escalators, moving handrails assist passengers in maintaining body balance by synchronizing with step tread movement. Stable handrail operation is particularly critical for vulnerable groups such as the elderly and children. Combining national industry standards and practical engineering cases, this paper systematically analyzes the root causes of handrail operational instability and proposes targeted optimization and standardized maintenance strategies.

Escalator handrails are classified into C-section and V-section structures, which are applicable to low-lift and high-lift escalators respectively. The friction wheel driving mode is widely adopted in commercial and public transit escalators. Long-term cyclic operation inevitably causes handrail tensile elongation and traction attenuation. Therefore, scientific tensioning systems are indispensable to maintain stable friction and consistent handrail-step synchronization.  https://www.deysse.com/product/Escalator-Rubber-Handrail-Belt-Material-SWE-Type-GS01708018-124.html

2. Mandatory Requirements for Escalator Handrail Systems in Safety Technical Codes

Clause 5.6.1 of GB 16899-2011 stipulates that the permissible speed deviation of handrails relative to step treads ranges from 0 to +2%. The industrial standard T/CEA 3017-2022 further supplements unified stability evaluation criteria for handrail systems, providing authoritative technical guidelines for daily inspection, fault diagnosis and rectification.

3. Root Causes of Unstable Handrail Operation

3.1 Deformation and Damage of Handrail Guide Rails

Continuous extrusion from circulating handrails easily leads to guide rail deformation, aging and joint misalignment. Structural defects generate lateral operating resistance, causing handrail jitter, transverse swing and jumping displacement, which is most prominent at upper and lower curved transition sections. Case Study: In 2023, an escalator in an eastern China shopping mall exhibited obvious handrail jumping during peak passenger flow. On-site inspection verified that deformed and misaligned curved rail joints caused unsmooth operation and minor passenger imbalance. The equipment regained full stability after rail replacement and flatness recalibration. https://www.deysse.com/product/Escalator-Parts-Guide-Rail-Straight-2000mm-GS00721003-3058.html

3.2 Insufficient Roller Lubrication and Deflector Wheel Wear

Insufficient bearing lubrication increases rotational resistance of support rollers, while worn coating layers of deflector wheels weaken damping performance. These defects collectively cause handrail speed lag and step desynchronization. Case Study: In 2024, a metro escalator in Hangzhou suffered persistent handrail speed deviation of 1.8%, nearly exceeding the standard limit. The fault originated from long-term dry friction of bearings and severe deflector wheel coating wear. Timely lubrication and component replacement reduced the deviation to within 0.5%, restoring stable synchronous operation. https://www.deysse.com/product/Escalator-Parts-HDZ0103-011-Handrail-Drive-Guide-Wheel-Size-70-50mm-2676.html

3.3 Speed Detection Encoder System Failure

Excessive or insufficient handrail tension, encoder coaxial deviation, mechanical fatigue and guide rail contamination will trigger signal distortion and monitoring failure, resulting in irregular handrail movement. Case Study: In 2023, frequent false speed alarms occurred on escalators at a major airport terminal. Troubleshooting confirmed that sugary beverage residues caused uneven guide rail friction, while encoder installation offset led to unstable signal output. Complete rail cleaning and precision calibration thoroughly eliminated the system fault. https://www.deysse.com/product/Escalator-Pulse-Encoder-REV-Transmitter-OEM-KM3714152-GS00356002-747.html

3.4 Non-compliant Routine Maintenance

Irregular and non-standard maintenance is one of the dominant human-induced causes of handrail instability. TSG T5002-2017 clearly defines standardized periodic maintenance requirements for handrail systems. Case Study: In 2024, a Haikou shopping mall failed to conduct quarterly tension calibration and speed detection for over one year. Aging tension components caused continuous handrail slippage and excessive speed deviation, eventually leading to a passenger fall accident, which fully reflects the safety risks of inadequate maintenance.

Standard maintenance specifications require quarterly speed deviation verification, semi-annual tension spring calibration and speed system inspection, as well as annual comprehensive examination of rollers, pulleys and sliding components.

4. Preventive and Optimization Measures

4.1 Mechanical Optimization of Guide Rails and Rollers

The clearance between handrails and guide rails shall be controlled within 8 mm via multi-point sampling detection. Gaskets are used for gap compensation, and severely deformed guide rails shall be replaced timely. Equipped with fully sealed self-lubricating bearings and real-time pressure monitoring modules, the system can balance roller load and effectively suppress handrail transverse vibration.

4.2 Precision Calibration of Tensioning Mechanisms

All tensioning devices shall be calibrated strictly in accordance with manufacturer’s technical parameters. For high-lift and high-traffic escalators in public hubs, the calibration cycle shall be appropriately shortened to avoid handrail slippage caused by insufficient tension or accelerated component wear caused by over-tensioning.

4.3 Technical Upgrade of Speed Detection Systems

Accurate and stable speed detection is the core guarantee of handrail-step synchronization. System reliability and environmental adaptability can be improved through targeted technical upgrades.

Encoders with IP67 and higher protection grades, anti-fouling coatings and automatic cleaning devices are adopted to adapt to complex operating environments. Bearing-free TMR magnetoelectric encoders and dual-redundant monitoring configuration eliminate single-point failure risks, significantly improving long-term operational stability.

4.4 Standardization of Full-Cycle Maintenance

A standardized full-cycle maintenance mechanism shall be established. Technicians conduct biweekly tension inspection and appearance detection, verify speed deviation with laser velocimeters, clean rolling components and calibrate detection probes regularly, and test handrail protection functions. Manufacturers shall formulate scenario-based maintenance guidelines with clear parameter thresholds, while maintenance institutions shall strengthen professional training to improve fault diagnosis and repair capabilities.

5. Conclusion

Handrail operational stability is a core indicator of escalator operational safety and riding comfort. This paper summarizes four key improvement strategies: optimizing mechanical support components, realizing precise tension calibration, upgrading speed detection systems, and standardizing full-cycle maintenance management.

Future research will focus on intelligent real-time monitoring technology, high-performance handrail materials and non-contact traction systems, so as to further improve the overall safety level and operational reliability of escalator handrail systems.

References

[1] State Administration for Market Regulation of China. TSG T5002-2017, Rules for Elevator Maintenance[S]. Beijing: China Quality and Standards Publishing & Media Co., Ltd., 2017.
[2] China Elevator Association. T/CEA 3017-2022, Technical Specification for Operation and Maintenance of Escalator Handrail Systems[S]. Beijing: China Elevator Association, 2022.
[3] National Standardization Administration of China. GB 16899-2011, Safety Code for the Construction and Installation of Escalators and Moving Walks[S]. Beijing: China Standards Press, 2011.
[4] Ministry of Science and Technology of the People’s Republic of China. National Key R&D Program Project (2023YFC3010405): Research on Key Technologies of Intelligent Safety Monitoring for Elevator and Escalator Equipment[R]. 2023.