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.
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.
Key facts
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 timeline
Application submitted to the patent office
Application published, typically 18 months after filing
Patent officially issued
Patent enters public domain
This patent is in the public domain
See the Freedom to Build guide — what is free to use, what is not, and how to cite this patent.
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.
Claim text not yet imported for this patent
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.
Embed
Add this patent to your site
Drop this plain-English patent card into any blog post or article — free, no signup. It always links back to the full breakdown here.
<div data-patentlens-widget data-patent-number="US723325"></div> <script src="https://patentbrief.org/embed.js" async></script>
Stay in the loop
Get a weekly digest of new patents.
One email per week. No spam. Unsubscribe anytime.
Keep exploring
Related patents you should know
US 4683195 · 1987
How to Make Billions of Copies of a DNA Segment
This patent describes the Polymerase Chain Reaction (PCR), a method to rapidly create many copies of a specific piece of DNA or RNA, enabling its detection and analysis.
Cetus Corp
US 8697359 · 2014
How to Edit Genes in Human Cells Using an Engineered CRISPR System
This patent describes an engineered CRISPR-Cas9 system for precisely cutting DNA in eukaryotic cells to change how genes work, opening the door for gene editing in complex organisms.
Massachusetts Institute of Technology
US 7657849 · 2010
How the iPhone's Slide-to-Unlock Gesture Works
Apple's 2010 patent describes unlocking a device by dragging a specific graphical image across the touchscreen along a predefined path, a gesture that became iconic with the original iPhone.
Apple Inc
US 4733665 · 1988
How Doctors Implant a Permanent Stent Using a Balloon
This patent describes the method for placing a permanent, expandable wire mesh tube inside a blood vessel or other body tube using a balloon-tipped catheter to widen it and keep it open.
Expandable Grafts Partnership
US 4965188 · 1990
How to Make Many Copies of a DNA Piece with Heat
This patent describes the Polymerase Chain Reaction (PCR) method, a technique to make millions of copies of a specific DNA segment using a heat-resistant enzyme and repeated temperature changes.
Cetus Corp
US 4235871 · 1980
How to Encapsulate Active Materials in Lipid Bubbles Efficiently
This patent describes a method for trapping biologically active substances inside tiny, multi-layered fat bubbles called liposomes, using a specific water-in-oil emulsion and gel-forming process to improve how much material gets captured.
Individual
Semantically similar
You might also find these interesting
More to explore
More in Energy & Clean Tech
US RE49155 · 2022 · Halliburton Energy Services Inc
Electric or Natural Gas Blending and Pumping for Oil Wells
US 11436484 · 2022 · Nvidia Corp
Nvidia's Method for Training Self-Driving Car AI in Simulations
US 11840398 · 2023 · Titan Trailers Inc
How Titan Trailers Builds Stronger, Smoother Cargo Containers
US 2708656 · 1955
How the First Nuclear Reactor Works
New to patents?
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
More from Individual
Patent monitoring