Radial Shaft Seal Patents: Top Companies & Filing Trends 2026
- One filer holds 21 of the 80 records in scope, and the top five combined account for 51.2% of all filings — this field concentrates fast past the leader.
- Filings grew 50% from 2021 to 2024 (2 to 3 a year), a real but modest acceleration, not a surge, and 2025-2026 counts are still filling in as publications lag filing.
- F16J covers 83.8% of the 80 records, while adjacent classes like coatings (C09D) and bearings (F16C) sit at 3.8% each — most of the open claim space is outside the core seal-body class.
Filing growth compares 2021 (2 records) with 2024 (3) — a three-year span. 2024 is the most recent year we treat as complete: publication lags filing by roughly 18 months, so 2025 onwards are still filling in and any growth rate that ends there would understate the field. Top-5 share is the combined record count of the five largest assignees divided by all 80 records in scope (CR5), not by the ranked leaders only.
What radial shaft seal patenting covers
Radial shaft seal patents cover the lip geometry, hydrodynamic pumping features, and material choices that keep a rotating shaft sealed against a housing bore. Claims in this space typically address lip contact pressure, friction torque under running conditions, shaft surface finish interactions, and the dry-running behaviour that determines seal life once lubricant film breaks down. Testing claims — leakage rigs, torque measurement setups — sit alongside the physical seal designs and are searched together here because the two are usually prosecuted in the same filing.
The dataset spans 80 published records from 2015 through the 2026 cut-off, drawn from national and PCT filings across the United States, Japan, Europe, India and Germany. Because publication trails filing by roughly 18 months, the most recent one to two years understate actual filing activity and should be read as provisional.
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Filing trend and technology composition
Two views of the same 80-record set: how filing volume has moved year over year, and which IPC subclasses the claims actually sit in. Because a single record can carry several IPC codes, the class shares below add up to more than 100% of the record total.
A slow build, not a rush
Filings peaked so far at 4 in 2020. The 2021-to-2024 span shows +50% growth (2 to 3 records a year) — real movement, but from a small base. Treat 2025 and 2026 figures as incomplete rather than as a slowdown.
F16J dominates; the rest is thin
F16J (pistons, seals and gaskets) covers 83.8% of the 80 records — the core claim space for lip geometry and contact pressure. Every other class sits at 6.3% or below, including plastics shaping (B29C), tyres (B60C), cycle frames (B62K), coatings (C09D), bearings (F16C), springs and dampers (F16F), and turbines (F01D).
Shares are the percentage of the 80 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Radial Shaft Seal Design and Testing with Eureka
This page is one run against one query. Ask Eureka your own question about radial shaft seal design and testing and every answer comes back with the patent numbers behind it.
Try EurekaMost-cited prior art and a recent representative filing
Hydrodynamic sealing element for a radial shaft seal (US20240309952A1)
A hydrodynamic sealing element for a radial shaft seal includes a radial flange leg encircling a rotation axis and an oblique flange leg joined to it, forming an oblique angle. The oblique flange leg carries an air-side surface and end face meeting at a lip, with a plurality of hydrodynamic indentations extending into the leg from the air-side surface. The element may be formed from leather, with the indentations created by debossing.Filed by Amsted Rail Company, Inc., published 2024-09-19.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US6729624B1 | Radial shaft seal | 87 |
| 2 | US5577741A | Combination lip and sleeve seal and its method of manufacture | 80 |
| 3 | US20050098959A1 | Sealing Ring, Especially Radial Shaft Seal | 69 |
| 4 | US20070057472A1 | Radial seal and method of making | 66 |
| 5 | US3363911A | Shaft seal | 60 |
| 6 | US3482844A | Shaft seal | 37 |
| 7 | US7172201B2 | Sealing ring, especially radial shaft seal | 28 |
| 8 | DE19922842A1 | Radial shaft seal comprises sealing ring with backflow device which has spiral groove extending between air s… | 22 |
| 9 | US20040160016A1 | Bonded PTFE radial shaft seal | 18 |
| 10 | US6988733B2 | Bonded PTFE radial shaft seal | 16 |
Citation counts favour older filings simply because they have had longer to accumulate citations inside this corpus — read them as a signal of influence on subsequent designs, not as a ranking of current importance.
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Three patterns stand out once the ranking and class data are read together: where claim density already blocks easy filing, where growth is real but small, and where citation weight sits on older art.
The top five hold half the field
With the leader alone at 21 records and the top five combined at 41 (51.2% of all 80 records in scope), new entrants are filing into a space where core lip-geometry and hydrodynamic-pumping claims are already well staked by a small group.
Modest, real acceleration
The three-year climb from 2 to 3 records a year is genuine growth but off a small base — this is not a boom, and treating 2025-2026 dips as decline would be a misread given the publication lag.
Most claim activity sits in one subclass
F16J absorbs the bulk of filings; every adjacent class — plastics shaping, tyres, bearings, coatings, dampers, turbines — sits at 6.3% or under, suggesting the seal-body claim space is dense while cross-domain applications remain lightly claimed.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to radial shaft seal design and testing, with the prior art for and against each one.
| Assignee | Co-assignee | Shared families |
|---|---|---|
| Federal Mogul Corporation | HATCH FREDERICK R | 3 |
| Federal Mogul Corporation | TOTH DAVID M | 1 |
| Federal Mogul Corporation | HATCH FEDERICK RONALD | 1 |
| Trelleborg Sealing Solutions US Inc. | Trelleborg Sealing Solutions Germany GmbH | 1 |
| FTL Seals Tech | SAMPSON DAVID CHRISTOPHER | 1 |
| HATCH FREDERICK R | TOTH DAVID M | 1 |
Only 6 co-assignee pairs appear in the dataset, and the strongest pairing links a single corporate filer to two named inventors — co-assignment here reads as inventor credit within one company rather than cross-company collaboration.
Leaders, momentum and where the gate sits
The ranked list covers 37 companies across the 80 records in scope. Activity concentrates hard at the top, and recent-year momentum across the named leaders reads flat rather than falling — a function of the publication lag rather than a real pullback.
A single filer well ahead of the field
The top-ranked assignee holds 21 of the 80 records in scope, more than double the fifth-place filer's count of 4 — a gap wide enough that competitive filings need to differentiate sharply on lip geometry or material rather than compete head-on.
A tight second tier
Between fifth and tenth place the record counts narrow to a tight band, with tenth place at 3 — this is where most active, still-competitive filers sit rather than at the very top.
Flat recent-year signal, not a retreat
Named leading assignees show 0 filings in the latest year, including one at -100% YoY. Given the roughly 18-month publication lag, this reads as pipeline still filling in rather than firms exiting the space.
| Assignee | Recent year | YoY |
|---|---|---|
| Federal Mogul Corporation | 0 | — |
| Trelleborg Sealing Solutions US Inc. | 0 | -100% |
| NOK Corp. | 0 | — |
| KACO GmbH & Co KG | 0 | — |
| Federal Mogul World Wide LLC | 0 | — |
| FTL Seals Tech | 0 | — |
| Amsted Rail Co Inc | 0 | — |
| Freudenberg-NOK General Partnership | 0 | — |
Where to take this analysis
The dataset points to a concentrated core and a thin periphery. Turning that into a filing or freedom-to-operate decision means going one level deeper than the aggregate figures shown here.
Map claims against the leader's 21 records
Before drafting into lip geometry or hydrodynamic pumping claims, check how the top filer's granted claims are scoped — the gap to fifth place (4 records) suggests broad coverage, not just volume.
Explore assignee claims in EurekaTest the under-claimed adjacents
Coatings, bearing integration and damper-coupled designs each sit under 4% of records — worth a formal novelty search before assuming the space is open.
Run a white-space search in EurekaTrack the next 12-18 months of publications
2025-2026 filings are still arriving under the publication lag; re-check the trend once 2025 closes out to see if the 2021-2024 growth rate held.
Set up monitoring in EurekaCommon questions on radial shaft seal patents
One assignee leads the ranked list with 21 of the 80 records in scope, well ahead of the fifth-placed filer at 4. The top five combined hold 51.2% of all records, so the field is concentrated at the top even though 37 companies appear across the full ranking. Anyone assessing freedom to operate should look closely at that leader's claim scope before assuming a gap exists.
Filings grew 50% from 2021 to 2024, moving from 2 to 3 records a year — a real but modest acceleration rather than a surge. The peak year so far is 2020, at 4 records. 2025 and 2026 figures look lower only because publication trails filing by roughly 18 months; they should not be read as a decline.
F16J, the pistons-seals-and-gaskets class, covers 83.8% of the 80 records in scope and is the core class for lip geometry and contact-pressure claims. Smaller shares sit in plastics shaping (B29C, 6.3%), tyres (B60C, 5.0%), and several classes at 3.8% each including coatings, bearings, dampers and cycle frames. Because records can carry multiple classes, these shares add up to more than 100% of the record total.
This 2024 filing from Amsted Rail Company describes a hydrodynamic sealing element with a radial flange leg and an oblique flange leg meeting at a lip, where the oblique leg's air-side surface carries hydrodynamic indentations — notably including a leather-based embodiment with debossed indentations. It sits within the dominant F16J claim space and specifically narrows to indentation geometry and material choice on the oblique leg. Anyone designing a hydrodynamic pumping feature on a similar flange geometry needs to check this claim scope directly rather than assume the leather/debossing detail is incidental.
The adjacent classes each sit at 6.3% of the 80 records or below — coatings (C09D), bearing integration (F16C), damper coupling (F16F) and turbine adaptations (F01D) among them. These low counts suggest less prior art to clear for claims that combine core seal geometry with a coating formulation or bearing-integrated assembly. That said, low volume in a narrow topic search does not guarantee true novelty, so a targeted freedom-to-operate search is still the right next step.
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Disclaimer. This page is generated from Patsnap Eureka data drawn from a limited snapshot of global patent and scientific-literature records, and is provided for general information and reference only.
Patent data carries inherent limitations: recent filings (typically the most recent 18–24 months) are under-counted due to standard publication lag; counts may be reported at either a patent-family or a patent-record basis and are not always directly comparable; classification, applicant-name, and citation data may contain errors, duplicates, or omissions; and the underlying search query defines and constrains the scope shown. As a result, the analysis may be incomplete or inaccurate and may not reflect the full technology landscape.
Nothing on this page constitutes an exhaustive prior-art, novelty, freedom-to-operate, or validity search, nor does it constitute legal, financial, investment, or professional advice, and it should not be relied upon as such. Any patent, commercial, or strategic decision should be verified independently and reviewed with qualified patent, legal, and domain professionals. Patsnap makes no warranties, express or implied, as to the accuracy, completeness, or fitness for any particular purpose of the information presented.
Machine translation. Assignee and organisation names originally recorded in Chinese, Japanese or Korean have been rendered into English by an AI translation step so that the tables stay readable. These renderings are best-effort and may not match a company’s registered English name; the original name is what the underlying patent record carries, and it is what any Eureka query launched from this page uses.