Leamon Souder's 1903 Design for a Spiral Escalator

A 1903 patent for a mechanical staircase that moves in a circular, spiraling path to transport people between floors.

What it covers

The patent describes a mechanical system where steps are mounted on a continuous chain that follows a helical or spiral track. As the chain moves, the steps rise or descend while simultaneously rotating around a central axis. This design intended to save space compared to traditional straight escalators by allowing the stairs to fit into a circular shaft.

What it doesn't cover

• —Does not cover standard linear escalators that move in a straight line.
• —Does not cover elevators that use a vertical cable-and-pulley system.
• —Does not cover stationary spiral staircases that lack a motorized moving mechanism.

The clever bit

The innovation lies in the geometry of the track, which forces the steps to maintain a level orientation while navigating a curved, three-dimensional path.

Why it matters

This patent represents an early attempt to solve the problem of vertical transportation in confined urban spaces. While spiral escalators are rare today due to their extreme mechanical complexity and maintenance costs, the concept remains a fascinating niche in the history of civil engineering.

Real-world examples

• 1.Spiral escalators found in high-end shopping malls like the ones in the Westfield San Francisco Centre.