Hydraulic Actuator Sealing Patents: Who Leads, Where the Gaps Are 2026
- Filing has cooled since its 2021 peak. 22 families that year against 3 so far in the partial 2026 count, with the 2022 midpoint of 17 already below peak — a flat-to-declining curve, not a growing one.
- F15B fluid-pressure actuator claims dominate the corpus. 228 of 298 records sit in F15B against 139 in F16J seals proper, meaning most filings claim the seal inside a broader actuator system rather than the seal alone.
- The US and China lead receiving offices by a narrow margin. 69 US filings versus 66 in China, with Japan, EPO, PCT and Australia trailing well behind — filing strategy here is genuinely bi-polar, not US-centric.
Filing growth compares 2021 (22 records) with 2024 (12) — 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 298 records in scope (CR5), not by the ranked leaders only.
What this landscape covers
This dataset tracks patent families at the intersection of hydraulic actuator and cylinder design and dynamic sealing claims — rod seals, leakage prevention, and related sealing devices — filed or published between 2015 and mid-2026. The search combines actuator-level terms with seal-specific claim language and IPC codes centred on F16J15 and F15B15/14, so it captures both dedicated seal patents and actuator patents that claim sealing as a subsystem.
Coverage runs to a 2026-07-31 cut-off. Because publication typically lags filing by around 18 months, the most recent one to two years in any trend line will look thinner than actual filing activity once those applications publish.
Filing trend and technology composition
Two views of the same 298-family corpus: how filing volume has moved year over year, and how that volume splits across the IPC subclasses that actually cover this technology.
A 2021 peak followed by a decline
Filings rose from 11 in 2017 to a peak of 22 in 2021, then eased to 17 by the 2022 midpoint and down to 3 in the still-publishing 2026 window. Read the tail end cautiously given the publication lag, but the shape through 2022-2025 already shows the peak is behind, not ahead.
F15B and F16J carry the corpus
F15B (fluid-pressure actuators, 228 records) and F16J (pistons, seals and gaskets, 139 records) account for the bulk of activity, with smaller pockets in F16F dampers, earth-moving equipment (E02F), valves (F16K), jacks (B66F), tunnel support (E21D) and test equipment (G01M) — evidence that sealing claims are being written primarily from the actuator side rather than as standalone seal geometry.
Shares are the percentage of the 298 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Hydraulic Actuator Sealing Technology with Eureka
This page is one run against one query. Ask Eureka your own question about hydraulic actuator sealing technology and every answer comes back with the patent numbers behind it.
Try EurekaRepresentative filing
Rod seal leak recovery system (GB2365073A)
A seat suspension leak recovery apparatus for a hydraulic cylinder with a main piston rod seal. A housing mounted to the cylinder defines a chamber around the main seal to capture fluid that leaks past it, with a second rod seal on the housing itself preventing recovered fluid from escaping, plus a vent and drain tube feeding a separate fluid recovery system.Filed by Sears Manufacturing Company; published 2002-02-13.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US4003297A | Hydraulic cylinder | 89 |
| 2 | US4807890A | Sealing combination | 88 |
| 3 | US4936197A | Dynamic seal construction | 47 |
| 4 | JP1997133215A | Sealing device | 39 |
| 5 | US5269537A | Composite radial seal | 38 |
| 6 | US6626438B2 | Seal assembly for telescopic hydraulic cylinder | 35 |
| 7 | JP2000009106A | Rod seal structure of hydraulic cylinder | 33 |
| 8 | US4889351A | Hydraulic seal | 30 |
| 9 | DE19754700A1 | Vehicular brake or clutch cylinder has two-stage seal | 28 |
| 10 | CN101725588A | 一种变形活塞间隙密封式液压缸 | 27 |
Citation counts favour older records simply because they have had more time to accumulate citations inside this searched corpus — treat them as a signal of influence on later filings, not as a ranking of current commercial relevance.
Patent titles are shown in the language they were filed in, not translated, so that each record stays verifiable against the original filing — a translated title will not match in Eureka or in any national register. Each row carries its publication number; clicking a row searches Eureka by that number.
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Three figures from this corpus matter more than the raw counts: where filing activity is trending, where claim density concentrates, and where citation weight sits relative to filing date.
The growth phase has passed
Filings peaked at 22 in 2021 and have declined through the 2022 midpoint of 17 down toward single digits by 2026. Even allowing for publication lag understating the last one to two years, the trajectory through 2022-2025 is already downward, not accelerating.
Sealing claims ride inside actuator claims
Three-quarters of the corpus sits in F15B fluid-pressure actuator classifications rather than F16J seal classifications alone. New entrants writing seal-only claims are competing against a smaller, more open subset of the field than the headline count suggests.
No single dominant jurisdiction
The US leads China by only three filings, with Japan, the EPO, PCT and Australia well behind both. A freedom-to-operate check for this technology needs both US and Chinese prior art, not one as a proxy for the other.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to hydraulic actuator sealing technology, with the prior art for and against each one.
Who is filing, and where activity has stalled
Assignee-level filing has gone quiet across the board in the latest year — a pattern consistent with the broader post-2021 decline rather than any single firm exiting the space.
A synchronized pause, not a single exit
Every assignee with recent-year momentum data shows zero filings in the latest tracked year, including large equipment makers. That pattern lines up with the corpus-wide decline rather than one company stepping back from sealing technology specifically.
A ranking with a long tail
With 298 families spread across the full assignee ranking, no single filer is likely to hold a commanding share; equipment OEMs and specialist seal manufacturers both appear in the same pool.
Watch both US and Chinese filers
With the US and China nearly level as receiving offices, competitive tracking needs to cover both English- and Chinese-language assignees; several of the latter are large earth-moving and construction equipment groups rather than dedicated seal specialists.
| Assignee | Recent year | YoY |
|---|---|---|
| Caterpillar Inc. | 0 | -100% |
| Trelleborg Sealing Solutions US, Inc. | 0 | — |
| KYB Corporation | 0 | — |
| Weber-Hydraulik GmbH | 0 | — |
| Atkinsick Company | 0 | — |
| Deere & Company | 0 | — |
| CHROMEGUARD PTY LTD | 0 | — |
| Hitachi Construction Machinery Co., Ltd. | 0 | — |
Where to take this analysis
The dataset points to specific next steps depending on whether the goal is freedom-to-operate, white-space filing, or competitive tracking.
Run a freedom-to-operate check on rod seal geometry
With F16J and F15B claims this dense, a new rod seal design needs a claim-by-claim check against the most-cited records before committing to a filing budget.
Explore in EurekaMap the E02F and E21D overlaps in detail
Sealing claims tied to earth-moving and tunnel-support equipment are a small fraction of the corpus but sit on distinct duty cycles that general hydraulic seal art may not cover.
Explore in EurekaTrack assignees through the next publication window
Because publication lags filing by around 18 months, the 2025-2026 filing counts shown here will rise as more applications publish — worth re-checking before concluding the decline is final.
Explore in EurekaCommon questions about hydraulic actuator sealing patents
This landscape tracks 298 patent families published between 2015 and mid-2026, drawn from a search combining hydraulic actuator and cylinder terms with dynamic sealing claim language. The figure reflects families, which is the fairer unit than raw document counts because it neutralises duplicate filings across jurisdictions and continuation applications. Because publication lags filing by roughly 18 months, the true count for 2025-2026 filings will rise as those applications publish.
Filing activity peaked in 2021 at 22 families and has declined since, with the 2022 midpoint at 17 and a partial 2026 count of only 3. Even accounting for publication lag understating the most recent years, the trend through 2022-2025 already points downward rather than upward. That makes this a mature, claim-dense field rather than an emerging one.
F15B, covering fluid-pressure actuators and systems, accounts for 228 of the 298 records, well ahead of F16J (pistons, seals and gaskets) at 139. This means most sealing claims in this corpus are written as part of a broader actuator system claim rather than as standalone seal geometry. Smaller pockets appear in springs and dampers, earth-moving equipment, valves, jacks, tunnel support and test equipment.
The US leads narrowly with 69 receiving-office filings against 66 for China, followed by Japan, the EPO, the WIPO PCT route and Australia. The gap between the top two is small enough that neither jurisdiction can be treated as a reliable proxy for the other in a freedom-to-operate search. Any competitive or clearance analysis in this space needs to cover both English- and Chinese-language filings.
GB2365073A, filed by Sears Manufacturing Company, claims a leak recovery apparatus built around a housing that mounts to a hydraulic cylinder and forms a chamber around the main piston rod seal to catch fluid that leaks past it. A second rod seal on the housing itself prevents that recovered fluid from escaping, and a vent and drain tube route it to a separate recovery system. The claims are specific to this dual-seal recovery-chamber structure, not to rod sealing in general, which leaves room for alternative leak-management architectures that do not use a housing-mounted secondary seal and drain path.
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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.