Fire escape – ladder – or scaffold – Having transpositioning base and erecting means
Patent
1992-03-06
1993-10-19
Chin-Shue, Alvin C.
Fire escape, ladder, or scaffold
Having transpositioning base and erecting means
182 2, E04G 136
Patent
active
052537315
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a raisable and lowerable elevating tower which extends downwards over the bridge edge and to which is fitted a work platform projecting beneath the bridge, and having a chassis located on the bridge and exhibiting a bearing element which is vertical in the working position and is connected to the elevating tower by means of arms protruding over the bridge edge.
A device of this kind is known, for example, from European Disclosure Specification 156 304. As a vertical bearing element, there is here provided a so-called guide tower of considerable height. On its side pointing, in the operating position, towards the bridge edge, it has guide rails, in which a slide is guided which can be moved up and down by means of a lifting cylinder. To the slide are fastened jibs projecting perpendicularly to the guide tower, i.e. horizontally, which are firmly connected to the elevating tower. The rigid structural unit comprising elevating tower, jibs and slide is thus guided on the guide tower. The vertical position of the jibs determines the vertical position of the work platform.
Often it is necessary to cross over high obstacles disposed on the bridge edge, e.g. protective fencing, soundproofing walls or lighting masts, with the jibs. Although this can be done by using a sufficiently high guide tower, the elevating tower can then no longer be moved in a vertical direction in order to bring the work platform to the correct distance from the underside of the bridge support.
A further problem presents itself in connection with so-called truss bridges, the girders of which located at both sides of the carriageway comprise mutually alternating vertical columns and oblique ties, which are connected to one another at the top by horizontal trusses. Here, one is forced to reach with the jibs through the windows formed from column, tie and truss, to be precise, over or under the oblique tie. Depending upon the pattern of the latticework, this necessitates, at various locations along the bridge, different heights for the work platform, which is unacceptable.
SUMMARY OF THE INVENTION
The object of the invention is to propose a self-erecting bridge underview device, which crosses over high obstacles on the bridge edge and oblique lattice ties whilst allowing the height of the work platform to be altered, and is easy to construct and simple to use.
This object is achieved according to the invention, in the case of a bridge underview device of the generic type, by the elevating tower being received by a guide member and being movable in relation to this in the longitudinal direction of the tower, and by the arms being attached, in a horizontally axial manner, at one end to the bearing element and at the other end to the guide member and forming a double parallelogram, and by the arms, in relation to a mid-position perpendicular to the elevating tower, being free to swivel out to both sides.
In place of a guide tower, a relatively low bearing element is provided in the form of an essentially rectangular frame, to which a total of at least four mutually parallel running arms are directly attached. On the elevating tower side, the arms are attached to a guide member, on which the elevating tower is guided in vertically movable manner. Preferably, the arms are of such a length that, between the downwardly and upwardly pivoted end positions of the guide member, a height difference of at least 1.5 m or so can be obtained.
The vertical position of the elevating tower and of the thereby supported work platform can therefore be altered by two mutually independent means, firstly by moving the elevating tower in relation to the guide member and secondly by pivoting the arms up and down. This twin vertical adjustment facility enables the device to be used in the case of truss bridges, for, when the arms have to be pivoted downwards, the elevating tower can move correspondingly upwards and vice versa.
Since the vertical-adjustment ranges are added together, the range of adjustment of the e
REFERENCES:
patent: 3357517 (1967-12-01), Wagner
patent: 3608669 (1971-09-01), Lindsay, Jr.
patent: 4074790 (1978-02-01), Colbachini et al.
patent: 4154318 (1979-05-01), Malleone
patent: 4696371 (1987-09-01), Moog
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