Joints and connections – Having a joining piece extending through aligned openings in...
Reexamination Certificate
1999-11-22
2001-10-02
Browne, Lynne H. (Department: 3629)
Joints and connections
Having a joining piece extending through aligned openings in...
C403S168000, C052S651050, C052S638000
Reexamination Certificate
active
06296419
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates, in general, to the industrial sphere of tower cranes and relates, more specifically, to a device providing a connection between a pivot and a mast structure for tower cranes. This device providing dismantlable assembly between, on the one hand, the top of the mast of a tower crane, made up of superposed metallic framework elements of square horizontal section and, on the other hand, a fixed pivot, the envelope section of which is of square overall shape and which serves to support and to orientate the rotating top part of the crane, comprising in particular the jib. In particular, the connecting device that is the subject of the invention is suitable for assembling a pivot of square envelope section with a side of a given length, for example 2.5 meters, with a framework element of square section which has a longer overall length of side, for example longer than 2.5 meters.
In a way which is generally known, the connection between the fixed pivot and the top of the mast, in a tower crane, is provided by fishplate means similar to the means used for the dismantlable assembly between the mast elements of the same crane.
DESCRIPTION OF THE PRIOR ART
Thus, there are tower crane mast elements with vertical corner members (or uprights) of round cross section fitted with tangs at their lower end and with corresponding yokes at their upper ends, removable connecting pins connecting the tangs with the yokes. The pivot is coupled to the upper element of the mast via the legs of this pivot, the construction of which is identical to that of the means provided at the base of the mast elements. An embodiment of this kind is described, in particular, in Chinese utility model No. 94247749.9 in the name of the Applicant, filed on Dec. 22, 1994 and granted on Oct. 29, 1995 with the No. 222090. In this embodiment, the tangs and yokes which provide the connections between the elements are oriented at 45° with respect to the adjacent faces of these elements, and thus extend outside the basic square section of said elements.
The result of this, as far as the pivot is concerned, is a square useful cross section the length of the side of which is limited to about 2.3 meters, for an overall size of 2.5 meters. Furthermore, the overall height of the pivot is, in this case, relatively great.
There are also pivots equipped with fishplate-jointing means designed to suit mast elements the corner members of which consist of L sections. In this instance, reference may be made to French patent application No. 7218577 of May 18, 1972, in the name of the Applicant, published on Dec. 28, 1973 with the No. 2 185 217, which describes a fishplate-jointing device in which the top of an upright bears an inner fishplate in the shape of an angle bracket and two outer fishplates welded to this upright, while inner and outer reinforcements are welded to the base of an upright; this device is equipped with jointing pins which pass through the fishplate and the reinforcements. A device of this kind, when applied to assembling a pivot, entails that, for a pivot with an overall square cross section with a side 2.5 meters long, the square cross section of the mast structure may not exceed a side length of 2.5 meters.
The present invention sets out to avoid the drawbacks and limitations of the current devices for providing connection between pivot and mast structure, and it therefore has the following objectives:
to improve the characteristics (in terms of the loads handled or the maximum reach) of the tower cranes, these themselves being determined by the dimensions of the pivot, while at the same time allowing them to be transported with the size permitted for road transport, or in standardized containers of the “platform” type;
to reduce the bulk of tower crane pivots for transport, particularly their overall height.
SUMMARY OF THE INVENTION
To this end, the subject of the invention is essentially a device for providing a connection between a pivot and a mast structure for tower cranes, of the kind specified in the introduction and which comprises, in combination:
at each of the four corners of the pivot, at least one fishplate fixed in a vertical plane passing through a diagonal of the square horizontal section of the pivot, or parallel to this diagonal, each fishplate being pierced with at least one hole of horizontal axis, and all of the fishplates of the pivot lying within the permissible size for transporting this pivot;
at each of the four corners of the top of the upper mast element, at least one other fishplate fixed to the upper part of a corner member or upright of this mast element, on the inside of the upright, in a vertical plane passing through a diagonal of the square horizontal section of the mast element or parallel to this diagonal, each fishplate being pierced with at least one hole of horizontal axis, and all of the fishplates of the mast element lying inside the volume delimited by the four lateral regions of the mast element, and
removable horizontal connecting pins designed to be engaged through the holes in the fishplates of the pivot and the holes in the fishplates of the mast element, these holes coming into alignment at each of the four corners when the pivot is placed on the top of the mast element.
Thus, according to the invention, the connection between the fixed pivot and the upper mast element is achieved by four identical fishplates located at each corner of the pivot, in the plane of the diagonals of the square horizontal section of the pivot. The overall dimension of the fishplates of the pivot is included in the maximum size permitted for ordinary road transport or for transport in containers of the “platform” type, namely 2.5 meters. By contrast, the fishplates of the mast element are located inside the volume delimited by the lateral faces of this element, the pivot can be assembled by a mast element whose horizontal section is a square with a side longer than 2.5 meters. Each fishplate of the device which is the subject of the invention constitutes, from the mechanical point of view, a connection with off-centered neutral axes, transmitting loads between the pivot, the cross section of which has a side length of, for example, 2.5 meters, and the mast structure, the cross section of which has a side length longer than 2.5 meters.
In one embodiment of the invention, each fishplate of the pivot is fixed by welding under a corner region of the upper horizontal plate, generally square in shape, of the pivot. Advantageously, each fishplate of the pivot is also fixed by welding to the adjacent regions of vertical reinforcing pieces located on the four sides of the pivot, under its upper plate, and connected to the shell cylinder of said pivot.
According to a preferred embodiment of the connecting device that is the subject of the invention, the pivot comprises, at each of its four corners, a single fishplate located in the vertical plane passing through the diagonal of the square section of the pivot, whereas fixed to the upper part of each corner member or upright of the mast element are two parallel fishplates which are symmetric with respect to the vertical plane passing through the diagonal of the square horizontal section of the mast element, the two fishplates together forming a yoke in which the corresponding fishplate of the pivot can be inserted.
According to an advantageous arrangement, two superposed holes are pierced in the fishplates of the pivot, and in the fishplates of the mast element, so that two superposed connecting pins can be fitted at each of the four corners. The holes pierced in the fishplates of the pivot just like the other holes pierced in the fishplates of the mast element, are preferably fitted with hammering inserts, intended to increase the area of contact between these fishplates and the connecting pin passing through them, and therefore to reduce the hammering pressure.
According to an additional advantageous arrangement, a horizontal mounting plate is welded to the upper end of each corner member or
Lissandre Michel
Millet Yves
Bochna David E.
Browne Lynne H.
Oliff & Berridge PLC.
Potain (Societe Anonyme)
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