US3856113A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Framework construction
Assignee: Keijser & Co C AB
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Filing: 1972-11-17
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Granted: 1974-12-24
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Expires: 1992-11-17
Abstract
Abstract A novel framework construction, e.g., a ladder, is provided. It includes at least two longitudinal beams disposed in substantially parallel alignment. Each beam is of a novel construction having a cross-section in the form of a pair of legs joined by a web, the web including a central area of substantially uniform thickness, and a pair of lateral areas, each such lateral area being of gradually increasing thickness in a direction away from the central area. A plurality of struts is provided, the struts being disposed transversely between, and connected to, the beams, the struts further forming an interlocking connection with the web. A novel procedure for producing this framework construction is also taught.
Inventors
- 👤 E Engvall
- 👤 T Ritscher
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 22:36
CPC Classifications
E; E06; E06C; E06C7/00; E06C7/08; E06C7/082; E06C7/085; E04; E04C; E04C3/00; E04C3/02; E04C3/04; E04C3/06; E04C2003/0404; E04C2003/0408; E04C2003/0413; E04C2003/0421; E04C2003/0426; E04C2003/0434; E04C2003/0443; E04C2003/0452
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
164 words
A ladder comprising two longitudinal beams made of an extrudable light metal alloy disposed in a substantially parallel alignment, said beams having a generally H-shaped cross-section in the form of a pair of legs joined by a web, wherein the web includes a central area of substantially uniform thickness, and a pair of lateral areas, each such lateral area being of gradually increasing thickness in a direction away from said central area; the central area of the web having a plurality of openings therein; a plurality of equidistanced hollow struts made of an extrudable light metal alloy arranged substantially normal to and interconnecting said beams and having a generally rectangular cross-section; and opposite end portions of said struts being received in the openings in said web, each strut end portion being provided with a pair of flanges formed wedgingly to interlock with the central area and abut a portion of said lateral areas of the web of the beam adjacent said strut end portion.
Claim 2
Dependent Claim
164 words
A ladder comprising two longitudinal beams made of an extrudable light metal alloy disposed in a substantially parallel alignment, said beams having a generally H-shaped cross-section in the form of a pair of legs joined by a web, wherein the web includes a central area of substantially uniform thickness, and a pair of lateral areas, each such lateral area being of gradually increasing thickness in a direction away from said central area; the central area of the web having a plurality of openings therein; a plurality of equidistanced hollow struts made of an extrudable light metal alloy arranged substantially normal to and interconnecting said beams and having a generally rectangular cross-section; and opposite end portions of said struts being received in the openings in said web, each strut end portion being provided with a pair of flanges formed wedgingly to interlock with the central area and abut a portion of said lateral areas of the web of the beam adjacent said strut end portion.
Claim 3
Dependent Claim
109 words
A framework construction comprising at least two longitudinal beams disposed in substantially parallel alignment, each said beam being in the form of a pair of legs joined by a web, said web including a central area of substantially uniform thickness, and a pair of lateral areas, each said lateral area being of gradually increasing thickness in a direction away from the central area; and a plurality of struts, said struts being disposed transversely between and the ends of said struts being connected to said beams, said ends of said struts forming an interlocking connection with the central area and abutting a portion of said lateral areas of said web.
Claim 4
Dependent Claim
109 words
A framework construction comprising at least two longitudinal beams disposed in substantially parallel alignment, each said beam being in the form of a pair of legs joined by a web, said web including a central area of substantially uniform thickness, and a pair of lateral areas, each said lateral area being of gradually increasing thickness in a direction away from the central area; and a plurality of struts, said struts being disposed transversely between and the ends of said struts being connected to said beams, said ends of said struts forming an interlocking connection with the central area and abutting a portion of said lateral areas of said web.
Claim 5
Dependent Claim
71 words
The construction of claim 2, wherein said struts have a substantIally rectangular cross-section; and wherein said central area of said web of said beams is provided with a plurality of openings to receive end portions of said struts, each strut end portion being provided with at least one contact face shaped to fit into said central area of said web and wedgingly to abut with said lateral areas of said web.
Claim 6
Dependent Claim
48 words
The construction of claim 3 wherein each end portion of said struts comprises: two face-to-face juxtaposed contact faces cooperating clampingly to hold opposite side faces of said central area of said web; and contact faces having two opposite edges wedgingly abut with said lateral areas of said web.
Claim 7
Dependent Claim
26 words
The construction of claim 2 wherein the total length of said lateral areas comprises at least about 20 percent of the total length of the web.
Claim 8
Dependent Claim
42 words
The construction of claim 5 wherein each lateral area of said web increases in thickness in a general wedge-like manner with opposite faces of each of said lateral areas of said web including an angle of between about 10* and about 35*.
Claim 9
Dependent Claim
15 words
The construction of claim 6 wherein said angle is from about 14* to about 24*.
Claim 10
Dependent Claim
17 words
The construction of claim 2 wherein said legs of said beam have their free ends bent inwardly.
Claim 11
Dependent Claim
15 words
The construction of claim 8 wherein said inwardly bent leg ends comprise a bead-like end.
Claim 12
Dependent Claim
36 words
The construction of claim 2 wherein the ratio of the width of the central area of said web to the general thickness of the legs is in the range of from about 0.6 to about 1.8.
Claim 13
Dependent Claim
30 words
The construction of claim 2 wherein the ratio of the total web length to the length of the legs is in the range of from about 1.4 to about 1.9.
Claim 14
Dependent Claim
32 words
The construction of claim 2 wherein the ratio of the thickness of said central area of said web to the total length of said web is from about 0.04 to about 0.02.
Claim 15
Dependent Claim
27 words
The construction of claim 2 wherein said struts are hollow members made of an extrudable light metal alloy and wherein said struts have a generally rectangular cross-section.
Claim 16
Dependent Claim
20 words
The construction of claim 13 wherein said metal alloy is aluminum and wherein said struts have a generally rectangular cross-section.
Claim 17
Dependent Claim
81 words
The construction of claim 2, wherein (1) the ratio of (a) the sum of the length of the two lateral areas and the length of the central area to (b) the length of the central area is about 4 to 1; and (ii) the ratio of (a) the sum of the length of the two lateral areas and the length of the central area to (c) the sum of the length of the two lateral areas is about 2.5 to 1.
Claim 18
Dependent Claim
23 words
The construction of claim 15 wherein the ratio (i) is about 3.4 to 1.9, and the ratio (ii) is about 2.2 to 1.2.
Claim 19
Dependent Claim
36 words
The construction of claim 15 wherein the ratio of the width of the central area of said web to the general thickness of the legs is in the range of from about 0.6 to about 1.8.
Claim 20
Dependent Claim
16 words
The construction of claim 17 wherein said beams are made of an extrudable light metal alloy.
Claim 21
Dependent Claim
14 words
The construction of claim 18 wherein said beams are made of an aluminum alloy.
Claim 22
Dependent Claim
30 words
The construction of claim 15 wherein the ratio of the total web length to the length of the legs is in the range of from about 1.4 to about 1.9.
Claim 23
Dependent Claim
32 words
The construction of claim 15 wherein the ratio of the thickness of said central area of said web to the total length of said web is from about 0.04 to about 0.02.
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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) | 1977-12-23 | 1978-06-24 | 1978-12-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-23 | 1982-06-24 | 1982-12-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-23 | 1986-06-24 | 1986-12-24 | $7700.00 | Window Closed / Lapsed |