Replacing the handrail belt drive chain requires the operation of a qualified technician. The core steps include shutting down the escalator and disconnecting the power, removing the protective cover, loosening the drive chain, installing the new chain, and adjusting the tension. Specific procedures should be followed according to the equipment model manual.
Shutting down and safety preparations: First, disconnect the escalator's power supply and hang a "Do Not Power On" warning sign to prevent accidental start-up. Simultaneously, install safety railings at the top and bottom of the escalator to prevent unauthorized personnel from entering the work area.
Positioning the drive chain assembly: The handrail belt drive chain is usually located near the drive unit on the side of the escalator, connecting the drive spindle to the handrail pulley. First, remove the inner cover or protective cover around the drive unit (refer to the "Inner Cover Opening" operation mentioned in the reference information) to expose the drive chain and tensioning device.
Removing the old drive chain: Loosening the tensioning device: Use a special tool to adjust the drive chain tension bolts to release chain tension. If the tensioning device is spring-type, compress the spring and fix its position.
Disconnect the chain: Record the number of chain links and the connection method (e.g., spring clips, cotter pins, etc.). Use a chain wrench or screwdriver to remove the connecting pins and remove the old chain from the drive sprocket and handrail pulley.
Inspect related components: Check the drive sprocket, handrail pulley, and guide rails for wear or misalignment ("guide rail misalignment" in the reference information may cause the handrail to loosen). Replace them simultaneously if necessary.
Install the new drive chain: Selection and matching: The new chain's model, pitch, and length must match the original chain to ensure good meshing with the drive sprocket teeth.
Attaching and connecting the chain: Wrap the new chain around the drive sprocket and handrail pulley, and secure the pins using the original connection method, ensuring a secure and loose connection.
Adjusting the tension: Gradually tighten the chain using the tensioning device until the chain sag meets the standard (usually 2%-4% of the center distance between the two sprockets). Too tight a chain will increase wear, while too loose a chain can cause teeth to skip.
Testing and Acceptance
Manual Rotation: Slowly rotate the drive wheel to check if the chain runs smoothly and without jamming or abnormal noise.
No-Load Test Run: After restoring power, perform a short no-load run to observe the synchronization between the handrail belt and the steps, confirming that the drive chain is free from slippage or vibration.
Load Test: Simulate passenger load to verify system stability, and fine-tune the tension if necessary.
Precautions: Operation must strictly follow the equipment maintenance manual. Drive chain structures may differ between different brands (e.g., Kone, Schindler).
After replacement, record the chain replacement date and running time for future maintenance.
If the handrail belt loosening is caused by drive chain wear, check the handrail belt tension after replacement (refer to the "Tension Adjustment Device" operation in the reference information).