E04F 21/245
Rotary power trowels, i.e. helicopter trowels
Official title: {Rotary power trowels, i.e. helicopter trowels}
E04F21/245 (Rotary power trowels, i.e. helicopter trowels) appears on 217 US grants and 177 published applications in this corpus.
Search patents in E04F- Granted patents
- 217
- Published applications
- 177
- Assignees
- 64
- Inventors
- 281
- Latest grant
- 4 Aug 2026
Filings by year
| Year | Granted patents | Published applications |
|---|---|---|
| 1976 | 2 | 0 |
| 1977 | 3 | 0 |
| 1978 | 0 | 0 |
| 1979 | 0 | 0 |
| 1980 | 2 | 0 |
| 1981 | 0 | 0 |
| 1982 | 3 | 0 |
| 1983 | 3 | 0 |
| 1984 | 0 | 0 |
| 1985 | 2 | 0 |
| 1986 | 2 | 0 |
| 1987 | 4 | 0 |
| 1988 | 5 | 0 |
| 1989 | 5 | 0 |
| 1990 | 2 | 0 |
| 1991 | 3 | 0 |
| 1992 | 5 | 0 |
| 1993 | 3 | 0 |
| 1994 | 2 | 0 |
| 1995 | 4 | 0 |
| 1996 | 5 | 0 |
| 1997 | 5 | 0 |
| 1998 | 4 | 0 |
| 1999 | 8 | 0 |
| 2000 | 7 | 0 |
| 2001 | 2 | 1 |
| 2002 | 5 | 5 |
| 2003 | 8 | 4 |
| 2004 | 1 | 6 |
| 2005 | 6 | 10 |
| 2006 | 12 | 7 |
| 2007 | 5 | 3 |
| 2008 | 5 | 8 |
| 2009 | 4 | 12 |
| 2010 | 8 | 7 |
| 2011 | 4 | 5 |
| 2012 | 5 | 2 |
| 2013 | 5 | 3 |
| 2014 | 2 | 3 |
| 2015 | 4 | 3 |
| 2016 | 0 | 2 |
| 2017 | 5 | 6 |
| 2018 | 3 | 9 |
| 2019 | 4 | 4 |
| 2020 | 8 | 12 |
| 2021 | 4 | 10 |
| 2022 | 8 | 14 |
| 2023 | 7 | 12 |
| 2024 | 9 | 16 |
| 2025 | 9 | 5 |
| 2026 | 5 | 8 |
By publication year. Applications have been published since 2001. 2026 runs to 8 Oct.
Subgroups
Granted patents
Recent patents
- Battery pack powered trowel including blade pitch and speed control4 Aug 2026US 12,698,636 B2Milwaukee Electric Tool Corporation
- Decorative concrete with uniform surface and method of forming the same14 Apr 2026US 12,601,177 B2Shaw & Sons, Inc.
- Work machine17 Mar 2026US 12,577,743 B2Honda Motor Co., Ltd.
- Work machine10 Feb 2026US 12,546,067 B2Honda Motor Co., Ltd.
- Concrete surface mapping robots, systems, and methods for processing concrete surfaces27 Jan 2026US 12,535,818 B2Husqvarna AB
- Concrete trowel17 Sep 2026US 2026/0275733 A1Milwaukee Electric Tool Corporation
- Motorized bump cutter assembly18 Jun 2026US 2026/0168266 A1
- Anti-kickback control for battery pack powered trowels11 Jun 2026US 2026/0160079 A1Milwaukee Electric Tool Corporation
- Trowel assembly16 Apr 2026US 2026/0103903 A1
- Safety switch for a battery pack powered trowel16 Apr 2026US 2026/0106092 A1Milwaukee Electric Tool Corporation
Most cited
By later US patents
- Concrete leveling machine61US 5,129,803 AShimizu Construction Co., Ltd. · 1992
- Spaced-rotor ride-type surface working machine with single-stick control of all movements58US 4,046,484 A1977
- Ride-type surface-working machines56US 3,936,212 A1976
- Light weight, fast steering riding trowel51US 5,108,220 AAllen Engineering Corporation · 1992
- Apparatus and method for improving the control of a concrete screed head assembly50US 7,044,681 B2Somero Enterprises, Inc. · 2006