Fire escape – ladder – or scaffold – Ladder – Supporting surface compensating means
Patent
1987-01-29
1988-09-13
Machado, Reinaldo P.
Fire escape, ladder, or scaffold
Ladder
Supporting surface compensating means
2481883, E06C 744
Patent
active
047702753
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a levelling apparatus comprising adjustable support legs and in one particular form can be detachably mounted to a ladder to compensate for variations in the surface on which the support legs are to rest. In another form, the apparatus can be incorporated in a ladder.
To overcome problems arising from uneven terrain, ladders have been equipped with slidably adjustable telescopic legs which can be fixed in a selected position by a locking screw so as to compensate for differences in level between the two legs supporting the ladder. This arrangement, however, is cumbersome to use and difficult to adjust. Other previously published levelling devices are disclosed in the following patent specifications: 1975
With use of embodiments of the present invention, ladder legs can adjust rapidly for changes caused by subsidence or instability of the ground on which the ladder rests and this can take place safely with a user at the top of the ladder; furthermore, the invention permits adjustment of the ladder without the necessity of locking and unlocking the legs manually.
According to the present invention, there is provided a levelling apparatus for a structure comprising:
(i) substantially rigid, support guide means adapted to be fixed relative to the structure;
(ii) an elongated, flexible ligament arranged to extend along the support guide means and to be moveable therealong,;
(iii) a plurality of elongated leg guides;
(iv) support legs displaceably mounted in the respective leg guides and connected to the ends of the elongated ligament such that corresponding displacement of the support legs occurs during adjustment for levelling purposes, and during normal use the load of the structure is transmitted through the support guide means to the elongated ligament, which is thereby placed under tension and transmits the load to the support legs and characterised by
(v) the ligament being of substantially uniform continuous form along at least the portion arranged for engaging the support guide means whereby there is provided stepless adjustment of the legs and automatic adjustment to compensate for ground subsidence at one leg relative to the other.
Preferably, the support guide means has an elongated ligament engagement surface over which the ligament moves during adjustment of the legs and against which the ligament frictionially engages when under constant load, a portion of said engagement surface intermediate the legs being arranged at a higher level than end portions of the support guide means located nearer the legs.
In a preferred embodiment, the intermediate portion of the support guide means is a smoothly curved member, for example a shallow inverted V-shaped member having a groove for accommodating the ligament.
The end portions of the support guide means preferably comprise smoothly curved guide elements fixed adjacent the legs for guiding the ligament through a turn of about 90.degree.. The guide elements could be grooved wheels (providing frictional surfaces for the ligament are used elsewhere in the support guide means) or grooved blocks e.g. of plastics material.
Preferably, the elongated ligament is constrained so as to be guided in a respective channels between the co-operating support legs and the respective leg guides.
The elongated ligament can be selected from a range of different materials, but in a preferred embodiment comprises a wire rope.
Preferably, the intermediate portion of the support guide means has a surface texture to facilitate frictional engagement with the ligament. In a preferred embodiment, the ligament is a wire rope and the surface of the guide means has a series of ribs and grooves corresponding to the profile to the wire rope.
One aspect of the invention consists in a ladder incorporating a levelling device, for example by utilising lower portions of the stiles of the ladder as the leg guides. This application is especially beneficial when the ladder is a steel or aluminum ladder formed from tubular material. In the case of an aluminum ladder, the co
REFERENCES:
patent: 2289499 (1942-07-01), Husted
patent: 2330825 (1943-10-01), Hoit
patent: 2366829 (1945-01-01), Biery
patent: 2854180 (1958-09-01), Brunckhorst
patent: 2890824 (1959-06-01), Derby
patent: 2969126 (1961-01-01), Gardner
patent: 3173512 (1965-03-01), Sturdy
patent: 3258085 (1966-06-01), McCarty
patent: 3954241 (1976-05-01), Carlson
patent: 4095671 (1978-06-01), Forristal
patent: 4673061 (1987-06-01), Zeiset
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