Patent US4297829A successfully refreshed from Google Patents.
US4297829A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Lawn mower blade rotation warning device
Assignee: Hoffco Inc
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Filing: 1980-10-10
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Granted: 1981-11-03
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Expires: 2000-10-10
Abstract
Abstract A warning device for a lawn mower having a rotary blade driven from a motor through a centrifugal clutch and normally held stopped by a brake which is released by a deadman control. The warning device comprises a flexible clicker post such as a close-wound helical spring carried by the clutch driver and having a weighted clicker head at its free end which normally stands in the path of a blade-mounting nut or other striker on the clutch-driven part so that the clicker head on the post will be repeatedly struck by the nut or other striker in the event the clutch driver element is stopped while the brake is disengaged and allows the blade to rotate under its own momentum. When the clutch driver is rotating at normal driving speed, centrifugal force bends the flexible arm to carry the clicker head out of striking relation with the striker element on the driven clutch part.
Inventors
- 👤 Stephen J. Hoff
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 11:50
CPC Classifications
A; A01; A01D; A01D34/00; A01D34/01; A01D34/412; A01D34/63; A01D34/67; A01D34/68; A01D34/6806; A01D34/6812; F; F16; F16D; F16D67/00; F16D67/02; A01D2034/6843; A01D2101/00
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
158 words
In a lawn mower having a rotary blade which is normally either driven by a motor through a releasable clutch having a driver connected to the motor or braked by a releasable brake, means for generating a warning signal in the event the clutch and brake are both sufficiently disengaged to permit the blade to rotate under its own momentum, said means comprising a striker carried with the driven blade, and a resiliently bendable clicker arm fixedly mounted at one end to said clutch driver and having a striking portion at its free end normally held by such arm in an operative position in the path of said striker so as to be struck thereby to generate an audible signal, said arm being resiliently bendable in response to centrifugal force so as to move said striking portion to an inactive position out of the path of the striker when the clutch driver is rotated above a predetermined speed.
Claim 2
Dependent Claim
158 words
In a lawn mower having a rotary blade which is normally either driven by a motor through a releasable clutch having a driver connected to the motor or braked by a releasable brake, means for generating a warning signal in the event the clutch and brake are both sufficiently disengaged to permit the blade to rotate under its own momentum, said means comprising a striker carried with the driven blade, and a resiliently bendable clicker arm fixedly mounted at one end to said clutch driver and having a striking portion at its free end normally held by such arm in an operative position in the path of said striker so as to be struck thereby to generate an audible signal, said arm being resiliently bendable in response to centrifugal force so as to move said striking portion to an inactive position out of the path of the striker when the clutch driver is rotated above a predetermined speed.
Claim 3
Dependent Claim
32 words
Apparatus as in claim 1 in which said arm is an axially extending arm fixed to said clutch driver in an eccentric position and has a striker mass at its free end.
Claim 4
Dependent Claim
30 words
Apparatus as in claim 2 which includes a blade carrier mounted for rotation coaxially with the clutch driver, and in which said striker is a blade-mounting element on said carrier.
Claim 5
Dependent Claim
18 words
Apparatus as in claims 1 or 3 in which said resiliently bendable arm is a helically wound spring.
Claim 6
Dependent Claim
30 words
Apparatus as in claim 2 in which said resiliently bendable arm is a helically wound spring, and said striker mass comprises a head fixed to the end of the spring.
Claim 7
Dependent Claim
25 words
Apparatus as in claim 5 in which the head is carried by a stem inserted within said spring and interengaged with the end turns thereof.
Claim 8
Dependent Claim
52 words
Apparatus as in claim 1 in which said arm is a helically wound spring mounted by one end in a hole in the clutch driver, said end containing a stem received within its end coils and having a press fit between the internal stem and the surrounding wall of the mounting hole.
Claim 9
Dependent Claim
65 words
Apparatus as in claim 7 in which the arm is mounted in an eccentric position on a radial wall of the clutch driver and said mounting hole extends through such wall, and said stem has protrusions thereon interengaged with the turns of the spring within the press-fitted portion and has a head thereon overlying the edges of said hole to fix the spring in place.
Claim 10
Dependent Claim
131 words
In a lawn mower having a rotary blade which is normally either driven by a motor through a releasable clutch having a clutch driver element connected to the motor, or is braked by a releasable brake, means forming a clutch-driven element and blade carrier, means for generating a warning signal in the event the clutch and brake are both sufficiently disengaged to permit the blade to rotate under its own momentum, said means comprising a striker carried by one of said clutch driver and driven elements, a helically wound spring forming a clicker post fixedly mounted in the other of said clutch driver and driven elements and having a clicker head at its free end in position to strike said striker during relative rotation of the clutch driver and driven elements.
Claim 11
Dependent Claim
131 words
In a lawn mower having a rotary blade which is normally either driven by a motor through a releasable clutch having a clutch driver element connected to the motor, or is braked by a releasable brake, means forming a clutch-driven element and blade carrier, means for generating a warning signal in the event the clutch and brake are both sufficiently disengaged to permit the blade to rotate under its own momentum, said means comprising a striker carried by one of said clutch driver and driven elements, a helically wound spring forming a clicker post fixedly mounted in the other of said clutch driver and driven elements and having a clicker head at its free end in position to strike said striker during relative rotation of the clutch driver and driven elements.
Claim 12
Dependent Claim
42 words
Apparatus as in claim 9 in which the clicker post is on the clutch driver element and is resiliently bent by centrifugal force to a position to stand clear of said striker when the clutch driver is rotating above a predetermined speed.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-11-02 | 1985-05-04 | 1985-11-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-11-02 | 1989-05-04 | 1989-11-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-11-02 | 1993-05-04 | 1993-11-03 | $7700.00 | Window Closed / Lapsed |