2.2.1 Step (Escalator) Chain
Small size conveyance: Escalator
Step Chain, which is also called Escalator Chain, moves the steps on escalators or drives moving sidewalks (Figure 2.9).
Figure 2.9 Step (Escalator) Chain
Construction and Features
In escalators, the steps are installed about every 400 mm, however, widths and heights are different. The tensile strength of step chains ranges from 6 to 30 tons. The 9-ton type and 15-ton type are most common.
The chain pitch should be as small as possible to reduce the effects of chordal action, which is caused by the chain/sprocket engagement. Using the smallest size possible allows the chain to operate more smoothly (Table 2.5).
The way steps are installed on chains differs from country to country. In Japan, the bearing part is in the center of the chain plate, so the step shaft is installed there. In other countries, extended pins are used as the shaft for the step (Figure 2.10).
|Pitch (mm)||Attachment Spacing|
Figure 2.10 Bearing Hole and Extended Pin on Step (Escalator) Chain
Usually rollers on the step side carry the weight of steps and passengers, but in some types the chain rollers carry the weight.
The features of step chain are:
- Greater wear resistance. The pin diameter is larger than standard chains.
- Length from step to step and from chain to chain is strictly controlled.
Special sprockets are required for step chains.
The chains shown above are being adapted for the following:
- Lubrication-free type. (However, lubrication is mandated at regular intervals.)
- Low-noise type (for quiet environments).