Patent US4457391A successfully refreshed from Google Patents.
US4457391A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fold-up ladder
Assignee: ANDRAL CORP
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Filing: 1982-01-21
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Granted: 1984-07-03
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Expires: 2002-01-21
Abstract
Abstract A portable folding ladder comprising a plurality of U-shaped modules having a rung and two vertical portions, the modules movable connected to each other, and when opened becoming progressible narrower as they approach the top of the ladder, when folded the narrower modules fitting inside of the next wider modules and locking means to lock the modules in a rigid manner when the ladder is extended and open.
Inventors
- 👤 D. Salvador Alimbau Marques
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 18:17
CPC Classifications
E; E06; E06C; E06C1/00; E06C1/52
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
143 words
A portable folding lean to ladder comprising a plurality of U-shaped modules comprising a rung and two vertical portions, said modules movably connected to each other, and when opened becoming progressively narrower as they approach the top of said ladder, when folded said narrower modules fitting inside of the next wider modules, said modules except for said widest base module comprising in their lower portions a complete module locking means and a module hinge means, said locking means fixing said modules in a rigid manner when said ladder is extended and open, said locking means integral with said modules and comprising latches adapted to movably fit into and mate with an aperture located in the upper sections of said vertical portions of said modules, and tapered grooved guide portions immediately adjacent said apertures to facilitate easy entrance of said latch into said aperture.
Claim 2
Dependent Claim
143 words
A portable folding lean to ladder comprising a plurality of U-shaped modules comprising a rung and two vertical portions, said modules movably connected to each other, and when opened becoming progressively narrower as they approach the top of said ladder, when folded said narrower modules fitting inside of the next wider modules, said modules except for said widest base module comprising in their lower portions a complete module locking means and a module hinge means, said locking means fixing said modules in a rigid manner when said ladder is extended and open, said locking means integral with said modules and comprising latches adapted to movably fit into and mate with an aperture located in the upper sections of said vertical portions of said modules, and tapered grooved guide portions immediately adjacent said apertures to facilitate easy entrance of said latch into said aperture.
Claim 3
Dependent Claim
18 words
The ladder of claim 1 wherein said hinges are postioned in the lower portion of said U-shaped section.
Claim 4
Dependent Claim
17 words
The ladder of claim 1 wherein said hinges are postioned above said latches in each U-shaped section.
Claim 5
Dependent Claim
28 words
The ladder of claim 1 wherein said hinges connect the lower portion of a U-shaped section to the upper vertical portion of the U-shaped section immediately below it.
Claim 6
Dependent Claim
23 words
The ladder of claim 1 wherein said latches are spring loaded permiting them to be locked in position when located in said aperture.
Claim 7
Dependent Claim
24 words
The ladder of claim 1 wherein said latches are connected to latch releases, said latch releases located externally of the rungs of said ladder.
Claim 8
Dependent Claim
29 words
The ladder of claim 1 wherein said aperture has immediately adjacent it on both sides, a tapered groove portion that permits easy entrance of said latch into said aperture.
Claim 9
Dependent Claim
12 words
The ladder of claim 1 wherein said latch and aperture are square.
Claim 10
Dependent Claim
21 words
The ladder of claim 1 wherein said latch and aperture have the same configuration to permit easy mating of the two.
Claim 11
Dependent Claim
25 words
The ladder of claim 1 said latch releases are movably located in the center portion of said rungs on the same level as said latches.
Claim 12
Dependent Claim
69 words
The ladder of claim 1 wherein said locking means are located in the bottom section of the narrower module and the top section of the next adjacent wider module, said locking means comprising a male member adapted to fit into and lock with an adjacent female member when said ladder is in an open and extended mode, said male member being positioned in the vertical portions of said ladder.
Claim 13
Dependent Claim
69 words
The ladder of claim 1 wherein said locking means are located in the bottom section of the narrower module and the top section of the next adjacent wider module, said locking means comprising a male member adapted to fit into and lock with an adjacent female member when said ladder is in an open and extended mode, said male member being positioned in the horizontal portions of said ladder.
Claim 14
Dependent Claim
29 words
The ladder of claim 1 wherein the vertical sections of said modules have tapered groove portions that permit easy entrance of said locking means into the next adjacent module.
Claim 15
Dependent Claim
17 words
The ladder of claim 1 wherein said hinges are positioned above said locking means in each module.
Claim 16
Dependent Claim
17 words
The ladder of claim 1 wherein said hinges are positioned below said locking means in each module.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-07-03 | 1988-01-02 | 1988-07-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-07-03 | 1992-01-02 | 1992-07-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-07-03 | 1996-01-02 | 1996-07-03 | $7700.00 | Window Closed / Lapsed |