Fire escape – ladder – or scaffold – Means maintaining platform level on angularly movable support – Swingable support
Patent
1984-02-06
1986-02-11
Machado, Reinaldo P.
Fire escape, ladder, or scaffold
Means maintaining platform level on angularly movable support
Swingable support
182 63, B66F 1104
Patent
active
045694168
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention is concerned with access equipment comprising a working platform or cage carried at a free end portion of a boom assembly which comprises a first boom pivotally mounted at one end portion on a support structure for movement about a first horizontal pivot and a second boom pivotally connected at one end with the free end portion of the first boom for pivotal movement about a second horizontal pivot, the working platform being pivotally supported at the free end portion of the second boom, separate power operated means, in the form of hydraulic rams, being provided for moving the two booms about the first and second horizontal pivots. Conveniently, the support structure includes a turntable mounted on a mobile platform for rotation about a vertical axis. The mobile platform may comprise either a self-propelled vehicle or a separately towable trailer.
BACKGROUND ART
In known kinds of access equipment of the kind under consideration it is usually necessary to provide fairly complex control equipment incorporating limit switches and valve arrangements whereby the required safety requirements may be met to avoid such sequences of movement of the booms which would cause the cage to be moved into positions where the equipment would become unstable. Furthermore known kinds of access equipment are usually fairly large and heavily constructed and are consequently expensive to manufacture.
The invention is concerned with the production of a relatively light-weight, simple and easily manufactured access equipment which has simple control gear and is of such a size it is particularly suitable for use by Do-it-yourself handimen and the like, is easily manoeuvered, and is towable by a domestic car.
DISCLOSURE OF INVENTION
According to the invention access equipment comprises an articulated boom arrangement for supporting a working platform or cage and comprising upper and lower booms, the lower boom being pivoted at one end portion to a turntable platform rotatable about a heightwise axis with respect to a trolley portion, the other end portion of the lower boom being pivotally connected to one end portion of the upper boom, the other end portion of which carries the working platform or cage, a first ram for moving the upper boom about its pivotal connection with the lower boom and a second ram for moving the lower boom about its pivotal connection with the turntable, characterized in that means is provided for limiting the movement of the lower boom under control of said second ram in such a way that, in its rest position, the lower boom is arranged to extend upwardly with respect to the turntable platform at an angle .theta. such that, in operation, the booms are not movable into positions in which the equipment becomes unstable.
Preferably, in access equipment as set out in the previous paragraph, the rest position of the lower boom is determined by the instroked position of the second ram. Similarly the limits of the positions to which the upper boom can be swung relatively to the lower boom are also conveniently limited by the stroke of the second ram and its size and positions of connection with the two booms. By way of example only, a suitable length of lower boom (having the above mentioned desiderata in mind) may conveniently be of the order of from about 2.75 m to 3 m, and the upper boom slightly longer so that, when the lower boom is in its rest position at the angle .theta. above referred to, the upper boom (in its rest position) extends downwardly at least substantially parallel to the lower boom to position the cage near the ground for easy access. Conveniently, the angle .theta. will be in the range of from 45.degree. to 55.degree. preferably in the range of 50.degree. to 52.degree. to the horizontal.
With a view to providing for ease of manoeuvering, the trolley portion of access equipment in accordance with the invention is provided with a first pair of wheels on which the equipment may be towed, with the boom arrangement in a more or less horizontal position but incl
REFERENCES:
patent: 2787278 (1957-04-01), Mitchell
patent: 3485321 (1969-12-01), Smith
patent: 4194591 (1980-03-01), Fisher
patent: 4360077 (1982-11-01), Abbott
Aerial Access Equipment Limited
Chin-Shue Alvin
Machado Reinaldo P.
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