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.
Original patent title: “Moving spiral stairway or elevator.”
A 1903 patent for a mechanical staircase that moves in a circular, spiraling path to transport people between floors. Granted to Individual in 1903 with 17 forward citations, and it is now in the public domain.
Key facts
Coverage
What does this patent actually cover?
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.
The gap
What does this patent NOT 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.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
What made this novel
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.
The Patent Drawing
Schematic visualization of the patent's claim structure. Hand-drawn diagrams in progress for each landmark patent.
Where you've seen this
Real-world examples
Spiral escalators found in high-end shopping malls like the ones in the Westfield San Francisco Centre.
Why it matters
The bigger picture
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.
Filed
March 24, 1902
Granted
March 24, 1903
Market context
Who's building on this
Companies in this space
Companies like Mitsubishi Electric are the primary modern manufacturers of spiral escalators, having refined the complex engineering required to make such systems safe and reliable for public use.
Market impact
This patent contributed to the early exploration of alternative vertical transport designs. It did not trigger a mass market shift, but it established a technical foundation for the specialized, high-cost spiral escalators used in luxury architecture today.
Claim 1 — Plain English
What this patent 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.
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.
What it does not 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.
Patent Journey
From filing to expiry
PatentBrief Score
Impact Score
Early stage
Citation count
25/40
Moderately cited
Claim breadth
0/20
Narrow claimsclaimsThe numbered statements at the end of a patent that legally define what the inventor owns.Read more →
Recency
0/20
Older than 20 years
Assignee scale
0/20
Independent or smaller assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →
PatentBrief Impact Score — based on citation count, claim breadth, recency, and assignee scale. Not a legal assessment.
Heuristic Value Estimate
What this patent might be worth
$8K – $26K
Midpoint $16K · expired or expiring · industry ×0.9
Heuristic only — blends forward/backward citation counts, claim scope, time remaining, litigation history, and CPC-derived industry baseline. Real valuations need a professional appraisal.
Concepts involved
Citations
Patent lineage
Cite this patent
Souder, L. G. (1903). Leamon Souder's 1903 Design for a Spiral Escalator (U.S. Patent No. 723,325). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/723325/escalator-moving-stairway
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
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Common Questions
Frequently Asked Questions
What does Leamon Souder's 1903 Design for a Spiral Escalator cover?
A 1903 patent for a mechanical staircase that moves in a circular, spiraling path to transport people between floors.
Who owns patent US 723325?
Individual owns this patent, granted in 1903.
When does this patent expire?
This patent has expired and is now in the public domain — anyone can use the invention freely.
What is patent US 723325 cited by?
This patent has been cited by 17 later patents that build on its ideas.
What problem does this patent solve?
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.
What does this patent NOT cover?
Does not cover standard linear escalators that move in a straight line.
Same assignee
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