PlainPatent

CPC technology class · E21

E21F - Safety Devices

Safety devices, transport, filling-up, rescue, ventilation, or draining in or of mines or tunnels. 641 US utility patents granted 2015–2025, with the leading assignees and year-by-year grant trajectory.

641
US patents granted
#4/4
in E21
1.5%
E21 class share
-6%
5-yr velocity

The verdict

According to USPTO PatentsView, Safety Devices ranks #513 of 670 CPC technology areas - 641 US patents granted since 2015, with recorded grant volume down 6% over five years.

#513
of 670 CPC technology areas
641
US patents granted, 2015–2025
China University of Mining…
leading assignee (70)
-6%
grant velocity, last 5 yrs

How E21F's grant cadence moved

Between 2020–2024, E21F recorded 265 grants versus 282 in 2015–2019 (-6% equal-window velocity). Across complete years, output peaked in 2019 at 73 grants and bottomed in 2015 at 40 (+83% peak-over-trough). Lead assignee China University of Mining and Technology holds 10.9% of the class ; the top three share 24.2%.

Leaderboard read

E21F concentration, lead at 10.9%

China University of Mining and Technology leads this historical grant record at 10.9% of E21F - foreign corporation assignees hold 55% of class grants (194 of 353). Figures describe granted US utility patents in this CPC subclass, not current investment or legal strength.

Leader's share
10.9%

70 of 641 grants

Top three share
24.2%

of the class's recorded grants

Lead over #2
23

more grants than Joy Global Underground Mining LLC

Where E21F sits inside E21

Among 4 subclasses in E21 (Earth OR Rock DRILLING; Mining), E21F ranks #4 and holds 1.5% of the parent class's 42,682 recorded grants. Sibling chips below are the other subclasses in the same parent class, not the nationwide volume/lead-share peers further down.

E21B 39,943 E21C 1,136 E21D 962

Rising assignees active in E21F

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. #1 Anhui University OF Science AND Technology 3.14x 7 → 22 company-wide · 8 in E21F
  2. #2 China University of Mining and Technology-Beijing 2.91x 11 → 32 company-wide · 13 in E21F
  3. #3 Taiyuan University OF Technology 2.40x 30 → 72 company-wide · 8 in E21F
  4. #4 Elkins Earthworks, LLC 2.00x 0 → 2 company-wide · 5 in E21F
  5. #5 Shandong University OF Science AND Technology 1.93x 29 → 56 company-wide · 15 in E21F

E21F grants by year, peak 2019 (73)

US utility-patent grants per year in E21F, 2015–2025 - recent five years are down 6% versus 2015–2019.

304050607080 20152016201720182019202020212022202320242025 33

Who leads E21F?

The 12 most active assignees in Safety Devices, Transport, Filling-up, Rescue, Ventilation, OR Draining IN OR OF Mines OR Tunnels - wider bars mean more grants

patents

What this shows China University of… is the most active filer in E21F, holding 70 of the 641 patents in this class. Concentration at the top signals how contestable this technology area is for new entrants.

Source USPTO PatentsView, granted utility patents As of 2015–2025 grant years
View data table
Top patent holders in CPC subclass E21F
Rank Company Patents in E21F
#1 China University of Mining and Technology 70
#2 Joy Global Underground Mining LLC 47
#3 Joy MM Delaware, Inc. 38
#4 Shandong University OF Science AND Technology 15
#5 China University of Mining and Technology-Beijing 13
#6 Jack Kennedy Metal Products & Buildings, Inc. 11
#7 Caterpillar Global Mining Europe GmbH 10
#8 Sandvik Mining and Construction Oy 8
#9 Taiyuan University OF Technology 8
#10 Anhui University OF Science AND Technology 8
#11 Floodbreak L.L.C. 8
#12 Electricwaze LLC 7
#13 Strata Products Worldwide, LLC 6
#14 Elkins Earthworks, LLC 5
#15 Technological Resources PTY Limited 4
#16 Imerys USA, Inc. 4
#17 Air Liquide Large Industries U.S. LP 4
#18 E. Dillon & Company 4
#19 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences 3
#20 The Mosaic Company 3

Footprint here vs. claim strategy

Each dot is a leading E21F 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 E21F assignees by class footprint. Bubble size = patents in E21F. Source: USPTO PatentsView (claim depth is company-wide across all classes). Scatter plot of 14 data points (bubble-sized by third dimension). 01020304050 020406080 Patents in E21F Avg claims / patent (company-wide) China University of…Joy Global Underground…Joy Mm DelawareShandong University…China University of…Jack Kennedy Metal…Caterpillar Global…Sandvik Mining and…Taiyuan University Of…Anhui University Of…Floodbreak L L CElectricwazeStrata Products…Elkins Earthworks
Top 14 E21F assignees by class footprint. Bubble size = patents in E21F. Source: USPTO PatentsView (claim depth is company-wide across all classes).

Classes near E21F's 641-grant footprint

Nationwide nearest neighbors for E21F (#513 of 670 by volume ; lead share 10.9%) - not the E21 parent-class siblings above.

Nearest by grant volume

D06B 640 A01J 653 E06C 653 G21G 629

Nearest by lead-assignee share

E01C 10.9% G21C 10.9% A01C 11.0% A45D 11.0%

Questions about E21F

Which company holds the most patents in E21F?
China University of Mining and Technology leads E21F with 70 patents (10.9% of the subclass). By PatentsView assignee type, foreign corporations account for 55% of class grants.
Which E21F assignees grew fastest recently?
Among assignees with ≥5 grants in E21F, Anhui University OF Science AND Technology shows the highest company-wide grant multiple (3.14x: 7 grants in 2019–2021 → 22 in 2022–2024) while holding 8 patents in this subclass. Growth is company-wide, not class-only.
How does E21F compare inside parent class E21?
Inside E21 (Earth OR Rock DRILLING; Mining), E21F ranks #4 of 4 subclasses by grant volume and holds 1.5% of the parent class total. The largest sibling is E21B (39,943 grants).

What to do with this data

E21F in context - here's where to go next.

  • China University of Mining and Technology leads E21F with 70 grants in this class. See full portfolio
  • E21F ranks #513 of 670 by grant volume among all tracked CPC technology areas. See the ranking
  • Inside parent class E21, the largest sibling subclass is E21B with 39,943 grants. Explore E21B

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

Methodology - E21F figures are USPTO PatentsView granted-utility totals for this subclass (641 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.