CPC technology class · B61

B61K - Auxiliary Equipment Specially Adapted For Railways

Auxiliary equipment specially adapted for railways, not otherwise provided for. 506 US utility patents granted 2015–2025, with the leading assignees and year-by-year grant trajectory.

Compiled by PlainPatent · May 15, 2026

506
US patents granted: #6/9
in B61: 6.2%
B61 class share: +20%
5-yr velocity

The verdict

According to USPTO PatentsView, Auxiliary Equipment Specially Adapted For Railways ranks #541 of 670 CPC technology areas - 506 US patents granted since 2015, with recorded grant volume up 20% over five years.

#541
of 670 CPC technology areas: 506
US patents granted, 2015–2025: Bnsf Railway
leading assignee (27): +20%
grant velocity, last 5 yrs

How B61K's grant cadence moved

Between 2020–2024, B61K recorded 245 grants versus 204 in 2015–2019 (+20% equal-window velocity). Across complete years, output peaked in 2024 at 69 grants and bottomed in 2016 at 31 (+123% peak-over-trough). Lead assignee Bnsf Railway Company holds 5.3% of the class ; the top three share 11.9%.

Leaderboard read

B61K concentration, lead at 5.3%

Bnsf Railway Company leads this historical grant record at 5.3% of B61K - us corporation assignees hold 72% of class grants (175 of 244). Figures describe granted US utility patents in this CPC subclass, not current investment or legal strength.

Leader's share: 5.3%
Top three share: 11.9%
Lead over #2: 7

Where B61K sits inside B61

Among 9 subclasses in B61 (Railways), B61K ranks #6 and holds 6.2% of the parent class's 8,123 recorded grants. Sibling chips below are the other subclasses in the same parent class, not the nationwide volume/lead-share peers further down.

B61L 2,671 B61D 1,451 B61B 961 B61C 870 B61F 797 B61H 502 B61G 314 B61J 51

Rising assignees active in B61K

Company-wide grant multiples (2022–2024 vs 2019–2021) among assignees with ≥5 patents in this subclass. Growth is company-wide; class patent counts are subclass-specific.

#1 Plasser & Theurer Export von Bahnbaumaschinen GmbH 11x 2 → 21 company-wide · 5 in B61K
#2 Ensco, Inc. 7.00x 2 → 14 company-wide · 12 in B61K
#3 Bnsf Railway Company 4.19x 21 → 88 company-wide · 27 in B61K
#4 Progress Rail Services Corporation 1.67x 12 → 20 company-wide · 8 in B61K
#5 Knorr-bremse Systeme FÜR Schienenfahrzeuge GMBH 1.46x 24 → 35 company-wide · 6 in B61K

B61K grants by year, peak 2024 (69)

US utility-patent grants per year in B61K, 2015–2025 - recent five years are up 20% versus 2015–2019.

Bnsf Railway

27
Tetra Tech

20
Amsted Rail

13
Ensco

12
International Machines

10
L B Foster Rail

10
Progress Rail Services

8
Ge Global Sourcing

7
Knorr-bremse Systeme…

6
Whitmore Manufacturing

6
Bombardier Transportat…

5
Smartdrive Systems

5

What this shows Bnsf Railway is the most active filer in B61K, holding 27 of the 506 patents in this class. Concentration at the top signals how contestable this technology area is for new entrants.

View data table

Top patent holders in CPC subclass B61K
Rank	Company	Patents in B61K
#1	Bnsf Railway Company	27
#2	Tetra Tech, Inc.	20
#3	Amsted Rail Company, Inc.	13
#4	Ensco, Inc.	12
#5	International Electronic Machines Corp.	10
#6	L.B. Foster Rail Technologies, Inc.	10
#7	Progress Rail Services Corporation	8
#8	GE Global Sourcing LLC	7
#9	Knorr-bremse Systeme FÜR Schienenfahrzeuge GMBH	6
#10	Whitmore Manufacturing, LLC	6
#11	Bombardier Transportation GmbH	5
#12	SmartDrive Systems, Inc.	5
#13	Plasser & Theurer Export von Bahnbaumaschinen Gesellschaft m.b.H.	5
#14	Harsco Technologies LLC	5
#15	Plasser & Theurer Export von Bahnbaumaschinen GmbH	5
#16	Sperry Rail, Inc.	5
#17	Georgetown Rail Equipment Company	4
#18	Precision Rail and Mfg., Inc.	4
#19	New York Air Brake LLC	3
#20	Crrc Qingdao Sifang Co., Ltd.	3

Footprint here vs. claim strategy

Each dot is a leading B61K assignee, placed by how many patents it holds in this class (horizontal) against its company-wide average claims per patent (vertical) - a read on whether the class is led by broad-but-shallow filers or focused deep-claim players.

Top 14 B61K assignees by class footprint. Bubble size = patents in B61K. Source: USPTO PatentsView (claim depth is company-wide across all classes).

Classes near B61K's 506-grant footprint

Nationwide nearest neighbors for B61K (#541 of 670 by volume ; lead share 5.3%) - not the B61 parent-class siblings above.

Nearest by grant volume

C12C 506 B27G 503 B61H 502 B28C 511

Nearest by lead-assignee share

C22C 5.3% A01P 5.4% H01F 5.4% A01M 5.3%

Questions about B61K

Which company holds the most patents in B61K?

Bnsf Railway Company leads B61K with 27 patents (5.3% of the subclass). By PatentsView assignee type, us corporations account for 72% of class grants.

Which B61K assignees grew fastest recently?

Among assignees with ≥5 grants in B61K, Plasser & Theurer Export von Bahnbaumaschinen GmbH shows the highest company-wide grant multiple (11x: 2 grants in 2019–2021 → 21 in 2022–2024) while holding 5 patents in this subclass. Growth is company-wide, not class-only.

How does B61K compare inside parent class B61?

Inside B61 (Railways), B61K ranks #6 of 9 subclasses by grant volume and holds 6.2% of the parent class total. The largest sibling is B61L (2,671 grants).

What to do with this data

B61K in context - here's where to go next.

Bnsf Railway Company leads B61K with 27 grants in this class. See full portfolio
B61K ranks #541 of 670 by grant volume among all tracked CPC technology areas. See the ranking
Inside parent class B61, the largest sibling subclass is B61L with 2,671 grants. Explore B61L

Figures reflect USPTO PatentsView grant data through 2026-05-15; pending applications not yet granted are not counted.

Methodology - B61K figures are USPTO PatentsView granted-utility totals for this subclass (506 grants in the tracked window).

Every figure on PlainPatent is rendered directly from USPTO source data, no number is typed in by an editor. This page draws directly on USPTO source data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.