Misaligned Axle Triggers Escalator Pile Up

Incident Investigation

Misaligned Axle Triggers Escalator Pile Up

December 1, 2017

Elevating Devices

Reference Number:


Location: Burnaby, BC

Incident Overview

An escalator pile up. The steps piled into the upper landing.

Site, System and Components

Escalator steps are attached to their axle by means of C-shaped clamps which are mounted onto a rotatable bushing. Spring loaded clips attached onto the C-shaped clamps clip into the step axle bushings and securing the step to the axle.

Failure Scenario(s)

The C-shaped clamp was not properly engaged and locked onto the rotatable bushing, this allowed the step to disengage from the bushing and caused axle misalignment. The misalignment caused the steps to come into contact with stationary components of the escalator and cause a step pile up.

Worn out step roller and chain roller allowed enough step misalignment that caused the step to engage stationary component of the escalator.

Facts and Evidence

All records indicate that the steps were replaced in July of 2017.

The C-shaped step clamp was reported to be not locked into the step axial rotatable bushing.

Causes and Contributing Factors

It is highly likely that the incident was a result of a securing pin not being fully engaged into the step axle bushing at the time of installation.
A person riding the escalator step caused further misalignment of the step and which might have contributed to the incident.

Worn step and chain rollers may have contributed to the incident.

Injury description: No injuries

Injury rating: None

Damage Description: Comb plates, steps, step chain sections.

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