Patent US3944024A successfully refreshed from Google Patents.
US3944024A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ladder
Assignee: Detroit Marine Engineering Corp
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Filing: 1975-02-06
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Granted: 1976-03-16
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Expires: 1995-02-06
Abstract
Abstract A ladder is made from extruded aluminum steps supported on a pair of vertical tubes fitted through large diameter holes drilled vertically through the steps. The steps are hollow except for a pair of vertical walls extending longitudinally thereof and lying on opposite sides of the vertical holes. Small horizontal holes are drilled through these walls from the rear of the steps to receive fastening pins which are driven through the tubes to locate and support the steps on the tubes.
Inventors
- 👤 Charles L. Adas
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 02:42
CPC Classifications
B; B63; B63B; B63B27/00; B63B27/14; E; E06; E06C; E06C7/00; E06C7/08; Y; Y10; Y10T; Y10T403/00; Y10T403/70; Y10T403/7075
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
81 words
A ladder including a plurality of steps each having top and bottom walls and a pair of inner transverse walls extending between said top and bottom walls, a pair of vertical openings extending through said steps between said vertical walls, a pair of tubular side rails fitted in the vertical openings of each of said steps, and fastener means projecting through said step transverse walls and each of said side rails to support and locate said steps on said side rails.
Claim 2
Dependent Claim
81 words
A ladder including a plurality of steps each having top and bottom walls and a pair of inner transverse walls extending between said top and bottom walls, a pair of vertical openings extending through said steps between said vertical walls, a pair of tubular side rails fitted in the vertical openings of each of said steps, and fastener means projecting through said step transverse walls and each of said side rails to support and locate said steps on said side rails.
Claim 3
Dependent Claim
14 words
The structure set forth in claim 1 in which said steps constitute metallic extrusions.
Claim 4
Dependent Claim
25 words
The structure set forth in claim 1 in which the spacing between said transverse walls is substantially equal to the span of said vertical openings.
Claim 5
Dependent Claim
25 words
The structure set forth in claim 1 in which said fastener means comprises a driven pin passing through preformed openings in said step transverse walls.
Claim 6
Dependent Claim
31 words
The structure set forth in claim 1 in which said steps comprise metallic extrusions and including resinous plastic plugs frictionally fitted into the ends of said steps and closing said ends.
Claim 7
Dependent Claim
20 words
The structure set forth in claim 1 including circumferentially split bushings fitted between said side rails and said transverse walls.
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) | 1979-03-16 | 1979-09-15 | 1980-03-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-03-16 | 1983-09-15 | 1984-03-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-03-16 | 1987-09-15 | 1988-03-16 | $7700.00 | Window Closed / Lapsed |