EP0024865A1

EP0024865A1 - Scaffolding joint

Info

Publication number: EP0024865A1
Application number: EP80302839A
Authority: EP
Inventors: Raymond Ernest Steele
Original assignee: Rapid Metal Developments Ltd
Current assignee: Rapid Metal Developments Ltd
Priority date: 1979-08-24
Filing date: 1980-08-18
Publication date: 1981-03-11
Also published as: IE801780L; AU6166980A; IE50048B1

Abstract

A scaffolding joint for connecting together a pair of scaffolding members (1) and (2) has a lug (4) on one member for co-operation with a bracket (5) on the other, and a wedge (6) arranged to retain the bracket (5) and lug (4) tightly in engagement. The wedge (6) has guide surfaces (23) arranged to co-operate with surfaces (25) on the bracket (5) to guide the wedge (6) to a retracted position and retention surfaces (24) arranged to co-operate with corresponding surfaces (26) on the bracket (5) to retain the wedge (6) in that position.

Description

This invention relates to a scaffolding joint for use in connecting together a pair of scaffolding members, such as an upright and a horizontal member or transom, for example, of a scaffolding structure. The joint of the invention is of the general kind, hereinafter referred to as "the kind specified" comprising a lug for attachment to one of the members, a complementary bracket for attachment to the other member, the lug and bracket respectively providing surfaces which are interengaged when the joint is assembled in order to interconnect the two members, and a wedge member which is mounted in the lug or bracket so as to be movable relative thereto between an operative locking position in which said interengageable surfaces of the lug and bracket are forced tightly into engagement with each other and an inoperative position in which disengagement of said surfaces is permitted.
A common problem with scaffolding joints of the general kind specified as proposed hitherto is that, when the bracket and lug are disengaged, it is difficult to ensure that the wedge is retained in a position permitting easy and rapid re-engagement of the bracket and lug since despite the use of various devices for retaining the wedge in a desired retracted position, these have not always been found to be entirely reliable in so retaining the wedge and are often, moreover, inconvenient to use. This can make it difficult and time consuming to connect scaffolding members together, particularly in the very common arrangement where brackets are connected to the respective ends of a horizontal member and it is necessary to ensure that the wedges of a pair of joints are positioned correctly to facilitate the engagement simultaneously of both brackets with their corresponding lugs.
An object of the invention is to provide an improved scaffolding joint of the kind specified in which the aforementioned problems are alleviated or avoided.
According to the present invention, in a scaffolding joint of the kind specified, the bracket or lug is provided with a guiding surface arranged for co_-operation with a surface of the wedge during retraction of the latter to guide the wedge into a predetermined retracted position in which the lug and bracket can be readily interengaged, and retention means are provided to act between the wedge and the bracket or lug to retain the wedge firmly in said retracted position.
In one preferred arrangement, the retention means is constituted by interengageable retention surfaces respectively on the lug or bracket and wedge; conveniently the retention surface of the wedge and the surface of the wedge co-operating with the guiding surface are both on a formation carried by the wedge and may face in different directions which are conveniently at 90° one to the other.
The invention will now be described, by way of example, with reference to the accompanying drawings in which:-

Figure 1 is a perspective view of one form of the joint of the invention;
Figure .2 is a cross-section along the line 2-2 of Figure 3 illustrating respectively, at either side thereof, the joint in its operative and inoperative conditions;
Figure 3 is a cross-section along the line 3-3 of Figure 2;
Figure 4 is a cross-section along the line 4-4 of Figure 2;
Figure 5 is a view similar to Figure 4, with part thereof removed, and
Figure 6 is a side elevation of a transverse member having a bracket and wedge of the joint of the invention respectively on each end thereof, the wedges being in their inoperative positions.

Referring to Figures 1 and 2 of the drawing, these show part of a scaffolding structure as used, for example, for building purposes, and including an upright member 1 and a transverse member 2, both in the form of cylindrical tubes which are connected together by a joint of the invention indicated generally at 3. The joint includes a lug 4 secured to the upright member 1 and a bracket 5 secured as by welding to the member 2 and embracing part of the lug, the lug and bracket being firmly locked in operative relationship by a wedge 6.
The upright 1 is provided at intervals along its length with sets of four lugs 4 at the same height and equi-spaced therearound, to enable up to four transverse members 2 to be mounted thereon, as required. The lugs could alternatively be arranged at different heights. The lugs are either secured directly to the tube 1 as shown, by welding for example, or formed on a collar secured around the tube. Each lug is of generally T-shaped cross-section with the web 7 of the T secured to the upright and the cross bar 8 of the T forming outwardly extending flanges 9 and 10 which are formed by pressing to provide protrusions 11 at either side and in a central region thereof. The web 7 increases in width upwardly so that the flanges 9 and 10 are inclined to the longitudinal axis of the tube 1, preferably by about 5°. The lower end portions 13 of the flanges 9 and 10 are bent inwardly and secured to the external surface of the upright 1 for additional rigidity and to serve as supports for the bracket 5 in some forms of the joint, although not in the one illustrated.
The bracket 5 of the joint is a tubular formation of generally rectangular cross section, the side 5A thereof being inclined to the side 5B carrying the member 2 at the same angle of inclination as that of the lug cross bar 8 to the upright 1. The side 5A also has a centrally located longitudinal slot 14 therein, open at the bottom and closed at the top, as seen in Figure 2 permitting the bracket 5 to be located over the lug 4 with the web 7 disposed within the slot and the closed end 14A of the slot resting on the upper edge of the web. As will be seen more clearly from the right-hand side of Figure 2, locking of the joint is effected by forcing the wedge 6 through the bracket between a wedging surface 15 of the bracket (split into upper and lower portions by removal of material at 16 for economy) and the protrusions 11 of the lug 4• The upper and lower portions of the wedging surface 15 provide areas of contact with the wedge respectively above and below the protrusions 11 of the lug, thereby ensuring a positive locking action by the wedge.
It would be possible for the slot 14 to extend continuously from the top to the bottom of the side 5A so as to be open at both of its ends. In this case, the lower edge of bracket 5 would rest on the lower end portions 13 of the flanges 9 and 10.
The wedge will be seen to comprise a solid tongue 17, the lower end of which is connected to a generally-H-shaped . formation 18 of which the arms 19 are interconnected by a thin web 20, the formation being stiffened by a rib 21. The side edges 19A of the arms 19 at one side of the wedge are chamfered at 19B, typically at 45°, to form the wedging surfaces of the wedge for engagement with the protrusions 11 of the lug, the outer surfaces of which are correspondingly angled. The side edges 19C at the opposite side of the wedge are plain and engage the surface portions 15 of the bracket when the wedge is in its operative position. As the wedge is driven into the bracket 5, engagement of the surfaces as aforesaid on the wedge, bracket and lug,
causes a force to be exerted on the bracket such as to urge the wall portions 5A of the bracket at either side of the slot 14 into tight engagement with the rear faces of the flanges 9 and 10, thereby firmly to interconnect the bracket and lug and thus the members 1 and 2.
When the joint is in its released condition, it is advantageous to be able to retain the wedge in a retracted position, as shown in Figures 2 (left-hand side) and 4, and to ensure that the wedge, when so retracted, will always be disposed in a position in which it does not obstruct insertion of the cross bar of the lug within the bracket. As will be seen more clearly from Figure 6, the wedge also has formations 22 projecting respectively from either side thereof and having thereon guide surfaces 23 and retention surfaces 24.
For the purpose of guiding the wedge to a desired retracted position, the bracket is formed with a pair of guide surfaces 25 on the opposed walls thereof transverse to that carrying the wedging surface 15, and these co-operate with the guide surfaces 23 whenever the wedge is retracted with its lower end in a position which would obstruct entry of the lug into the bracket as aforesaid. Retraction of the wedge with the guide surfaces 23 and 25 in engagement constrains the wedge to move across the bracket so that, when fully retracted, it is sufficiently spaced from the side 5A of the bracket to permit entry of the lug into the bracket. Ideally, the wedge, when fully retracted, would be approximately in the position shown at the left-hand side of Figure 2, resting against the upper wedging surface portion 15 of the bracket.
For retention of the wedge in its retracted position, the bracket is provided with a pair of opposed wedging surfaces 26 for co-operation with the wedging surfaces 24 of the wedge when the latter is in its retracted position. It will be appreciated that with the joint of the invention, not only is the wedge held effectively against displacement from its retracted position during normal conditions of use, but by virtue of the aforesaid guiding surfaces it is not possible for it to be retracted into a position in which passage of the lug into the bracket would be obstructed. This provides a considerable advantage over conventional arrangements since it means that the wedge can be simply and reliably retracted to the correct position by an upward pull without any particular care being taken by an operative.
The joint of the invention can be particularly advantageous when, for example, a pair of joint brackets are secured respectively to the ends of a horizontal member 2, as is quite common in practice and illustrated in Figure 6. In conventional arrangements, it has been found very difficult to hold both of the wedges 6 in correct retracted positions whilst at the same time manipulating the member 2 to locate the brackets 5 on the lugs of a pair of uprights. With the joint of the invention, it becomes a simple matter to raise the wedges to retracted positions, where they are retained and to engage the brackets onto lugs, as required.
It is particularly convenient to form the guiding surfaces 23 and retention surfaces 24 of the wedge on single formations 22 and located in two mutually perpend_- icular planes, since this simplifies manufacture. It will be understood, however, that they may be formed on different parts of the wedge and arranged in any convenient manner: The wedge is conveniently provided with a downwardly projecting tongue 30 which is of sufficient length that it always projects from the bracket 5 when the wedge is in its retracted position, enabling the wedge to be dislodged from that position, when desired, by an upward blow on the tongue.
Although the invention, as described, uses lugs 4 formed with protrusions 11 on the flanges 9,10, other forms of lug may be used having, for example, straight flanges with bevelled faces for engagement by the wedge surfaces 19. Although a group of four lugs are shown, any convenient number of lugs from one upwards may be provided. When a group of lugs is provided, the lugs may be spaced equally around the scaffolding member or arranged assymmetrically, both circumferentially and vertically. Moreover, the member 2 secured to the bracket 5 may take alternative forms such as an 'L' or inverted 'T' angle member, the horizontal flanges of which may be used to support planking for walkways. In all forms of the joint of the invention, the wedge may be provided with a formation, such as a lug or pip, arranged to prevent the wedge 6 from falling out of the bracket 5 when loosely located therein.
It would be possible to provide guide and retention surfaces 23 and 24 facing in opposite directions and arranged symmetrically at either side of the wedge, which means that the wedge is then completely reversible and may facilitate assembly of the wedge and bracket because no choice would be required as to the orientation of the wedge before insertion thereof into the bracket.
An alternative non-symmetrical form of wedge could be generally channel shaped, with the base of the channel bearing against the wedging surfaces 15 of the bracket and the free edges of the sides of the channel bearing against the protrusions 11, or equivalent parts, of the lug to provide the main joint wedging action. The wedge surface for co-operation with the guiding surface of the bracket or lug may then be provided on one or both sides of the channel and, when the retention means for the retracted wedge is constituted by interengageable retention surfaces respectively on the lug or bracket and wedge, such surface on the wedge may also be on one or both sides of the channel. Preferably, the guide and retention surfaces would be on protrusions formed on the channel sides similar to those shown at 22 in Figures 3 and 4, although not necessarily arranged for reversibility of the wedge.

Claims

1. A scaffolding joint of the kind specified in which the bracket or lug is provided with a guiding surface arranged for co-operation with a surface of the wedge during retraction of the latter to guide the wedge into a predetermined retracted position in which the lug and bracket can be readily interengaged, and retention means are provided to act between the wedge and the bracket or lug to retain the wedge firmly in said retracted position.

2. A scaffolding joint according to Claim 1 wherein the retention means is constituted by interengageable retention surfaces respectively on the lug or bracket and wedge.

3. A scaffolding joint according to Claim 2 wherein the retention surface of the wedge and the surface of the wedge co-operating with the guiding surface are both on a formation carried by the wedge.

4. A scaffolding joint according to Claim 2 or Claim 3 wherein the retention surface of the wedge and the surface of the wedge co-operating with the guiding surface face in different directions.

5. A scaffolding joint according to Claim 4 wherein said directions are at 90⁰ to each other.

6. A scaffolding joint according to any one of Claims 2 to 5 wherein the retention surface of the wedge and the surface of the wedge co-operating with the guiding surface are both divided into mutually spaced portions respectively at or near the sides of the wedge.

7. A scaffolding joint according to any one of the preceding claims wherein the wedge is carried by the bracket and is disposed in its operative position, to act between a surface of the bracket and at least one opposed surface of the lug to force the bracket and lug interengageable surfaces tightly into engagement with each other.

8. A scaffolding joint according to Claim 7 wherein said at least one opposed surface of the lug is formed on a protrusion of the lug extending outwardly of said one member.

9. A scaffolding joint according to any one of the preceding claims wherein the leading end portion of the wedge forms a tongue extending longitudinally of the wedge and arranged to project from the bracket when the wedge is in its retracted position.

10. A scaffolding joint substantially as hereinbefore described with reference to the accompanying drawings.