Accessory Gearbox Patents: Top Companies & Filing Trends 2026
- Concentrated at the top. the leading assignee alone accounts for 42 of 205 records, and the top 5 combined hold 65.9% of the field.
- Gas-turbine framing dominates. F02C and F01D classes cover 55.1% and 48.3% of records respectively, while gearing-specific F16H sits at just 20.0%.
- Filing has cooled from a 2017 peak of 34. but the 2021-to-2024 window (the last complete years) shows +17% growth, not a field in decline.
Filing growth compares 2021 (6 records) with 2024 (7) — 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 205 records in scope (CR5), not by the ranked leaders only.
What this landscape covers
This landscape tracks patents and published applications describing accessory gearboxes, tower shafts and radial drive shafts alongside the failure modes and interface hardware that define real-world reliability work in this area: spline wear, gear rattle, mounting and starter pads, carbon seal leakage and shear-neck design. It sits at the intersection of gas-turbine engine architecture and gearing, which is why the IPC composition leans so heavily on turbine classes even though the search terms are gearbox-specific.
The 205 records in scope span 2015 through the 2026 cutoff, with the most recent one to two years understated because publication typically lags filing by around 18 months. Filing activity, receiving-office footprint and IPC composition are shown next, followed by the assignee ranking, most-cited prior art, and the branches that remain thin.
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Filing trend and technology composition
Two views of the same 205-record dataset: filing activity by year, and how records distribute across IPC subclasses. Because a single record can carry several IPC codes, the class shares below add up to more than 100%.
Filing trend, 2015–2026
Filings peaked in 2017 at 34 and have run lower since; the last complete comparison window, 2021 to 2024, shows growth of +17% (6 to 7 records). Treat 2025 and 2026 figures as provisional given publication lag.
IPC subclass composition
Gas-turbine plant claims (F02C, 55.1% of records) and turbine mechanicals (F01D, 48.3%) frame most filings; dedicated gearing claims (F16H, 20.0%) and aircraft equipment (B64D, 19.0%) are meaningfully smaller, with clutches/brakes, motor control and cleaning classes trailing further behind.
Shares are the percentage of the 205 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Accessory Gearboxes and Power Take Off with Eureka
This page is one run against one query. Ask Eureka your own question about accessory gearboxes and power take off and every answer comes back with the patent numbers behind it.
Try EurekaRepresentative filing and most-cited prior art
Gas turbine engine with accessory gearbox (US11326523B2)
A gas turbine engine with an accessory gearbox. The accessory gearbox has a gear shaft rotatable about a gear shaft axis. The gear shaft has a first end drivingly engaged to a first accessory and a second end drivingly engaged to a second accessory. The gearbox has a spline made of a polymer material and rotatably coupled to one of the first and second ends of the gear shaft, and to a corresponding one of a first and second accessory shafts of the first and second accessories. The spline is rotatable about the gear shaft axis.Filed by Pratt & Whitney Canada; the polymer-spline coupling is the narrow but commercially relevant hook.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US6681579B2 | Air turbine starter with fluid flow control | 97 |
| 2 | US5610341A | Modular oil monitor | 80 |
| 3 | US5127220A | Method for accelerating a gas turbine engine | 73 |
| 4 | US20180149038A1 | Gas turbine engine wash system | 66 |
| 5 | US20030145602A1 | Air turbine starter with fluid flow control | 44 |
| 6 | US2952973A | Turbofan-ramjet engine | 37 |
| 7 | US20050232784A1 | Pump assembly | 33 |
| 8 | US20180283464A1 | Output assembly for an accessory gearbox of a gas turbine engine | 32 |
| 9 | US20130047624A1 | Distributed lubrication system | 24 |
| 10 | US20130051975A1 | Air turbine starter and method for venting without loss of oil | 24 |
Citation counts reflect influence within the searched corpus and skew toward older filings; they are a signal of historical reach, not of current claim strength.
Each row carries its publication number; clicking a row searches Eureka by that number.
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Browse MCP servers →What the numbers mean for a filing decision
Three findings that shape where new claims can realistically land in this space.
The top of the field is tight
With the leading assignee alone at 42 records and the top five combined holding 65.9% of all 205 records in scope, core accessory-gearbox architecture claims are already well staked out by a small group of engine and aerospace-systems manufacturers.
Gearbox claims ride inside turbine filings
Only a fifth of records sit in the dedicated gearing class F16H, while over half carry the gas-turbine plant class F02C. Most accessory-gearbox intellectual property is filed as part of broader engine-system disclosures rather than as standalone transmission patents.
Activity has not fallen off since the 2017 peak
Filings peaked at 34 in 2017 and have not returned to that level, but the most recent complete years show growth rather than decline: 2021's 6 records rose to 7 by 2024. Later years look lower only because publication lags filing.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to accessory gearboxes and power take off, with the prior art for and against each one.
Who is filing, and where the gaps sit
The ranked list covers 18 assignees across 205 records, dominated by aircraft-engine OEMs and their systems suppliers. Recent-year momentum shows the largest historical filers reporting zero records in the latest year across the board, consistent with a mature top tier and publication lag rather than a sudden exit from the field.
A single assignee anchors the field
The top-ranked assignee's 42 records make it the clear reference point for accessory-gearbox architecture; any new entrant's freedom-to-operate review should start with this portfolio before moving down the ranking.
A workable second tier exists
Fifth place sits at 16 records, and the top 10 combined reach 88.3% of all records, meaning the remaining eight of eighteen ranked assignees, plus unranked filers, share a small residual slice of the space.
Filing footprint centres on the US and Europe
The United States and the EPO account for the largest receiving-office counts, with Germany, Austria and Canada forming a secondary tier and WIPO/PCT filings comparatively rare, suggesting most applicants pursue direct national or regional protection over PCT routing.
| Assignee | Recent year | YoY |
|---|---|---|
| Pratt & Whitney Canada Corp | 0 | -100% |
| Hamilton Sundstrand Corp | 0 | — |
| GE Avio S.r.l. | 0 | — |
| General Electric Co | 0 | — |
| Astronics Advanced Electronic Systems Corp | 0 | — |
| Kawasaki Jukogyo KK (Kawasaki Heavy Industries) | 0 | — |
| United Technologies Corp | 0 | — |
| Honeywell International Inc | 0 | — |
Where to take this next
The dataset points to a small number of concrete follow-ups depending on what you're trying to decide.
Run a freedom-to-operate check against the top 5
With 65.9% of records held by five assignees, any new accessory-gearbox filing should be screened against their claim scope before drafting, particularly around gear-shaft and spline coupling language.
Screen the leading portfoliosScope claims around the under-claimed branches
Carbon seal leakage, polymer spline couplings and starter-pad mounting show lower filing density than the core turbine classes, which is where narrower, defensible claims are more likely to clear prior art.
Explore the white spaceTrack the next 12–18 months of publications
Because publication lags filing by roughly 18 months, the 2025–2026 dip in the trend chart is provisional; re-check the filing curve once those years fill in before concluding the field has slowed.
Monitor the filing trendCommon questions about accessory gearbox patents
In this dataset of 205 records, filings are concentrated at the top, with the leading assignee alone accounting for 42 records and the top five assignees combined holding 65.9% of all records in scope. This pattern is typical of aircraft-engine subsystems, where a handful of OEMs and their systems suppliers control most of the core architecture claims. Anyone entering this space should expect the leading portfolios to cover the fundamental gear-shaft and drive-train configurations, leaving more room in interface and failure-mode hardware than in base architecture.
Filings peaked in 2017 at 34 records and have not returned to that level since, but that is not the same as a declining field. The last full comparison window with complete data, 2021 to 2024, shows growth of +17%, rising from 6 to 7 records. Because patent publication typically lags filing by around 18 months, the apparent drop in 2025 and 2026 reflects incomplete data rather than reduced inventive activity.
Only 20.0% of the 205 records in scope carry the dedicated gearing class F16H, while 55.1% carry the gas-turbine plant class F02C and 48.3% carry the turbines/non-positive engines class F01D. This means most accessory-gearbox intellectual property is filed as part of a broader gas-turbine engine disclosure rather than as a standalone transmission patent, which affects how a search or freedom-to-operate review should be scoped: searching F16H alone would miss most of the relevant art.
The lower-frequency IPC classes in this dataset point to under-claimed branches: clutches and brakes (F16D, 7.8% of records), motor and generator control (H02P, 7.3%), electric motors and generators (H02K, 5.9%) and cleaning-related hardware (B08B, 3.4%) all sit well below the gas-turbine and gearing classes. Specific technical sub-areas within these, such as carbon seal leakage mitigation, polymer spline couplings and starter-pad mounting interfaces, show comparatively thin filing density and are worth a closer novelty search before drafting.
US11326523B2, assigned to Pratt & Whitney Canada, claims a gas turbine engine accessory gearbox where a gear shaft drives two accessories and one end of the shaft couples to an accessory shaft through a spline made of polymer material. The claim is narrow to that polymer-spline coupling detail rather than to accessory gearboxes generally, so it does not block conventional metal-spline or alternative coupling designs. Designs using non-polymer splines, or different accessory-coupling mechanisms entirely, sit outside its literal scope, though a full claim chart is needed before relying on that conclusion.
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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.