Joint for foldable aluminum ladders
US4666327A · kind A · utility
Inventor
Key dates
| Filing date | Sep 22, 1986 |
| Grant date | May 19, 1987 |
| Priority date | — |
| Expiry date | Sep 22, 2006 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T403/32361
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
A joint for foldable aluminum ladders comprising a first base, a second base, a control plate and a selecting means. The second base has a middle plate inserted between two parallel plates which are connected at the end of the first base. The control plate is inserted between one of the parallel plates and the middle plate. The parallel plates, middle plate and control plate each have a central hole to allow a sleeve to be inserted therethrough. The parallel plates, middle plate and control plate also have apertures which lay some distance along the edges. The selecting means has a fixing link inserted through the sleeve and an inserting link which is shorter than the fixing link. A compressible spring is disposed around the lower end of the fixing link and a nut is secured at the threaded portion of the fixing link. When the selecting means is pulled outwardly, the legs of the ladder can be freely rotated to adjust the angle of the ladder, then the angle of the ladder is fixed with the inserting link being inserted through the most appropriate apertures of the first base, second base and control plate.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.