What is the internal structure of an escalator?

An escalator is mainly composed of several key parts that work together to move passengers safely and smoothly. The main structure is the truss, a metal frame that supports the entire system. Inside the truss, there is a drive system (motor and gearbox) that provides power to move the escalator.

The step system consists of linked steps that form a continuous loop, allowing people to stand comfortably while moving. The handrail system runs alongside the steps and moves at the same speed to help passengers keep balance. At the top and bottom, comb plates are installed to ensure smooth entry and exit.

In addition, there are guide rails and rollers that keep the steps aligned and stable during operation. All these components work together to ensure the escalator runs efficiently and safely.

Escalator mechanical structure

The Mechanical Structure Of An Escalator Includes

trusses, timing brakes, guide rail system, handrails (skirt panels and anti-pinch devices, inner and outer covers, wall panels), handrail assembly, step chains, steps, comb teeth, support plates (front edge plates), inspection covers, and floor slabs (bed covers), etc.

The truss of an escalator supports its entire weight, external structure, and passenger load, providing fixed positions for the drive unit, handrails, guide rails, etc., and maintaining their relative positions. The escalator truss is welded from angle steel. The load on which the escalator support structure is designed is the self-weight of the escalator or moving walkway plus a load of 5000 N/m². The maximum deflection calculated or measured based on the 5000 N/m² load should not exceed 1/750 of the support distance L1. For public transportation escalators and moving walkways, the maximum deflection calculated or measured based on the 5000 N/m² load should not exceed 1/1000 of the support distance L1.

Truss

The guide rail system is divided into upper and lower steering guide rails and a middle linear guide rail system. The geometric relationships between the guide rails and return rails in the upper and lower steering guide rail systems are relatively complex. To accurately control the dimensions of each guide rail, the guide rail system includes a steering mechanism for the rotation of the ladder chain, a moving guide, and a tension adjuster structure to meet the tension requirements of the ladder chain.
The ladder guide rails ensure the ladder steps move according to a certain pattern to prevent deviation and bear the ladder load transmitted from the main and auxiliary pulleys. They have smooth, flat, and wear-resistant working surfaces.
To reduce the pressure on the guide rails and extend the service life of the tread rollers, the upper and lower guide rail operating radii are 2000mm and 1500mm respectively. The guide rails of the upper and lower steering guide rail systems are made of 10T, 8T, and 15T cold-drawn flat steel, while the guide rails of the middle guide rail system are made of 2.5T steel plates with a galvanized surface. They are reinforced with guide rail support plates and a metal frame.

Ladder Guide Rail System

Interior Panel
The panel located between the skirt panel (or inner decking) and the handrail cover (or handrail rail).
Inner Decking
The component connecting the skirt panel and the basalt panel when they do not intersect.
Outer Decking
The component connecting the outer decking and the basalt panel.
Skirting
The vertical portion of the handrail assembly adjacent to the steps, treads, or tape.
Skirt Deflector
A device that reduces the risk of pinching between the steps and the skirt panel.
Baluster Panel
If glass is used for the basalt panel, it should be tempered glass. The minimum thickness of a single pane of glass should be 6 mm. When multi-pane glass is used, it should be laminated tempered glass, and at least one pane should be at least 6 mm thick.

Handrail

Composed of rigid and flexible components (e.g., rubber profile); the protrusion from the vertical surface of the apron brush should be a minimum of 33mm and a maximum of 50mm; a force of 900N should be applied to the protruding area of the rigid component, perpendicular to the connecting line of the rigid component and acting uniformly on a rectangular area of 6cm², without causing detachment or permanent deformation;
The rigid component should have a horizontal protrusion of 18mm to 25mm and possess the specified strength. The horizontal protrusion of flexible components should be a minimum of 15mm and a maximum of 30mm;
In inclined sections, the vertical distance between the lowest edge of the rigid component of the skirt board anti-pinch device and the line connecting the front edge of the step should be between 25mm and 30mm;

In transition and horizontal sections, the distance between the lowest edge of the rigid component of the skirt board anti-pinch device and the highest point of the step surface should be between 25mm and 55mm;
The lower surface of the rigid component should form an upward inclination angle of not less than 25° with the skirt board, and its upper surface should form a downward inclination angle of not less than 25° with the skirt board;
The edges of the skirt board anti-pinch device should be rounded. Fasteners and connectors should not protrude into the operating area; The end portion of the skirt board anti-pinch device should gradually taper and smoothly connect with the skirt board. Protective anti-pinch device at a position of 50mm, maximum 150mm;

The handrail system consists of components on both sides of escalators and moving walkways that provide safety protection for passengers and facilitate their standing and gripping. There should be no part of the handrail system that allows for normal standing. The handrail is a power-driven moving handrail for passengers to hold onto while using the escalator or moving walkway. The handrail's movement path is controlled by handrail guides fixed to the railing. The guidance and tension of the handrail should prevent it from detaching from the handrail guides during normal operation.
The driving force of the handrail is provided by the main drive shaft, which drives the handrail drive shaft to rotate. The handrail on both sides is pressed tightly against the handrail friction wheels by handrail pressure pulleys. The handrail moves by the friction between the handrail friction wheels and the handrail. Because both the step chain and the handrail drive system are driven by the main drive shaft, the moving speed of the handrail can achieve a high degree of synchronization with the speed of the steps in the same direction.
The cross-section of the handrail and the forming assembly of its guide rails should not pinch or trap fingers and hands. The distance between the opening of the handrail and the guide rail or handrail support should never exceed 8mm. The width b2 of the handrail should be between 70mm and 100mm.

Handrail System

The step chain mainly consists of the step main wheel, inner and outer chain plates, shaped pins, cylindrical pins, and sleeves. One chain is installed on each side of the step, and the two chains are connected by a step shaft to pull the step together. The step chain is tensioned at the turning wall of the lower turning guide system via a tension adjuster to absorb chain elongation caused by wear and tear.
Escalator steps should be driven by at least two chains, with at least one chain on each side of the step.

Step Chain

Steps are specially structured four-wheeled carts with two main wheels and two auxiliary wheels. The main wheels are hinged to the step chain, while the auxiliary wheels are fixed to the steps. All steps run along guide rails arranged according to a specific pattern. Steps on the upper branches of the escalator remain horizontal, while steps on the lower branches can be suspended upside down.
Steps are fixed to the step axle and can be easily removed from the lower machine room without dismantling the axle and handrails, allowing for maintenance. Furthermore, escalators can be maintained and operated even without steps installed.

Steps

The skirt panels of escalators or moving walkways are located on both sides of the steps, treads, or belts. The horizontal clearance on either side should not exceed 4 mm, and the sum of the clearances measured at symmetrical positions on both sides should not exceed 7 mm. If the skirt panel of the moving walkway is located above the treads or belts, the vertical clearance measured between the tread surface and the lower end of the skirt panel should not exceed 4 mm. Lateral swaying of the treads or belts should not create a gap between the side of the treads or belts and the vertical projection of the skirt panel.

A single drive unit should not drive more than one escalator or moving walkway.Service Brake
Escalators and moving walkways should be equipped with a braking system that provides a near-uniform deceleration braking process until the escalator or moving walkway stops and remains stationary (service brake). The braking system should not be intentionally delayed during use. After the escalator or moving walkway starts, a device should monitor the release of the braking system.

Drive Unit