Patent US4722420A successfully refreshed from Google Patents.
US4722420A
Expired / Lapsed
US
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Special purpose ladder
Assignee: Individual
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Filing: 1986-11-17
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Granted: 1988-02-02
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Expires: 2006-11-17
Abstract
Abstract This ladder is designed to clamp to sign posts for workman safety. Primarily, it consists of a pair of stepped legs with a hinged shelf at the top having a clamp that clamps to a sign post. A second clamp is also provided below and is secured to arms attached to the legs, and a pair of extension rods are provided on the legs for stabilily of the legs on sloping ground surfaces.
Inventors
- 👤 Trudy Arthurs
- 👤 Harold S. Swartz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 09:45
CPC Classifications
E; E06; E06C; E06C1/00; E06C1/02; E06C1/34; E06C7/00; E06C7/42; E06C7/44; E06C7/46; E06C7/48
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
117 words
A special purpose ladder, comprising, a pair of legs, a plurality of rungs interconnecting said legs, a shelf fixedly secured at one edge to the top of said legs, a first clamp fixedly secured to another edge of said shelf, a second clamp located below said first clamp and pivotally secured by a pair of arms to said legs by suitable fasteners, a pair of extension rods slideably received in sleeves fixedly secured longitudinal to the sides of the lower portions of said legs, and said extension rods provide a means of engaging with a sloping ground surface to stabilize said ladder; whereby said ladder could be clamped to a single post by means of said clamps.
Claim 2
Dependent Claim
117 words
A special purpose ladder, comprising, a pair of legs, a plurality of rungs interconnecting said legs, a shelf fixedly secured at one edge to the top of said legs, a first clamp fixedly secured to another edge of said shelf, a second clamp located below said first clamp and pivotally secured by a pair of arms to said legs by suitable fasteners, a pair of extension rods slideably received in sleeves fixedly secured longitudinal to the sides of the lower portions of said legs, and said extension rods provide a means of engaging with a sloping ground surface to stabilize said ladder; whereby said ladder could be clamped to a single post by means of said clamps.
Claim 3
Dependent Claim
80 words
A special purpose ladder as set forth in claim 1, wherein each said extension rod is secured at any desired extension by means of a set bolt, said set bolt is received into an internally threaded projection fixedly secured to said sleeves at right angle and extending through an opening through said legs, and said set bolt which when tightened impinges against a floating collar surrounding the said extension rod wedging the said extension rod secure against the said sleeves.
References Cited (Backward Citations)
US347608A
Cited
US1138583A
Cited
US1142072A
Cited
FR1131322A
Cited
FR1313696A
Cited
US3268196A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-02-01 | 1991-08-03 | 1992-02-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-02-01 | 1995-08-03 | 1996-02-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-02-01 | 1999-08-03 | 2000-02-02 | $7700.00 | Window Closed / Lapsed |