IMPROVED COUPLERS

Abstract: The coupler (100) comprises a pair of U-shaped support members (112) having pivoted thereto an inverted U-shaped saddle (120). The support members (112) and saddle (120) intersect at (128) in a clamping condition to clamp a tube (124) in the coupler and outwardly extending arms (130) and (132) of the support members and saddle respectively may be urged apart by a wedging device (134) to provide the clamping force. The wedging device (134) is a toggle joint which in the undercentre condition (160) illustrated wedging engages the arm (132) which projects through an opening (146) in a locking arm (144). The arm (132) is radiused about an outwardly offset axis (152) relative to the pivot axis (137) of toggle joint (134). The toggle joint may be moved to an overcentre condition (162) in which the opposed edges of the opening (146) lockingly engage the upper and lower surface (150) and (151) of the arm (132), which may be serrated as at (148). The coupler (100) may be interlocked with a second identical coupler (100').

Description: IMPROVED COUPLERS The present invention relates to couplers for rods and is particularly, but not only, concerned with couplers for scaffolding tubes. The securing of scaffolding tubes one relative to the other is well known using couplers in which a scaffolding tube is received in a U-shaped support and a saddle pivoted to the support is clamped to the support to lock the scaffolding tube in place. The clamping of the saddle relative to the support is commonly performed using a nut and bolt assembly which may be totally releasable from the coupler or secured to one or other of the support and saddle. Such an assembly is disclosed, by way of example, in Figure 1 of French patent specification 2,234,804. One of the problems with assemblies of the type disclosed in Figure 1 of the French patent specification is the time taken to tighten and/or release the nut to clamp the saddle in place. It will be appreciated that a very large number of scaffolding couplers may be used on any one site and the total time for locking or releasing all of the couplers must be accounted for. Furthermore, there is a real possibility that the nut may be undone sufficiently from the bolt that it becomes separated from the bolt and very likely lost. Clearly, if the bolt is not secured to the coupler it also may become lost. Figures 3 to 7 of the French patent specification disclose proposals which alleviate the risk of parts of the coupler becoming lost by locking the saddle to the support using a wedging action. Thus, in one proposal a rotatable cam is proposed while in the other proposal a wedge-shaped cross-bar is used. In both of these proposals, the wedged portions of the support and saddle are urged towards each other and the maximum clamping action is determined by the wedged portions abutting each other. Furthermore, no means is provided for locking the wedging.device to alleviate the risk of the wedging device being accidentally loosened and thereby immediately releasing the scaffolding tube in a sliding manner through the coupler. According to the present invention there is provided a rod coupler comprising U-shaped support means adapted to at least partly receive a rod, such as a scaffolding tube, between the legs of the U-shape, saddle means pivoted adjacent one end to one of the legs of the support means for movement between a position in which the saddle means extends across the legs of the support means to be clamped over a rod received by the support means and a position in which the rod can be withdrawn from the support means, the support means and the saddle means intersecting to the side of the rod remote from the pivot in the clamping position, the other leg of the support means and the other end of the saddle means defining respective outwardly extending arms, and wedging means pivoted to one of the outwardly extending arms and adapted in the clamping position to engage the other outwardly extending arm to the distal side of the intersection to force the arms apart and thereby clamp the coupler around the rod. By the present invention, any inherent resilience in the outwardly extending arms can be used to reinforce the wedging action. Thus, the saddle means and the support means may be formed of an essentially rigid material, including the . outwardly extending arms, but the resilience introduced into the coupler by the length of the outwardly extending arms assists in the use of the coupler. Advantageously, the engagement of the wedging means is with a radiused portion of the other outwardly extending arm whose centre of curvature is offset outwardly from the pivot axis of the wedging means whereby as the engagement of the wedging means with the other arm is increased, the wedging action increases. The engagement of the wedging means may be with a serrated portion of the other arm or, alternatively, with a corrugated portion of the other arm in which each corrugation is defined by two arcuate parts, a first part of which has as its centre of curvature the pivot axis of the wedging means and a second part of which has its centre of curvature offset outwardly from the pivot axis. In each of the aforementioned serrated and corrugated embodiments, the wedging means may act in the manner of a ratchet mechanism and may be engaged with the other arm by a sharp blow such as with a hammer and disengaged from the other arm using a lever action between the wedging means and, for example, the intersection of the support means and saddle means, possibly followed up by a hammer blow. The wedging means may comprise a rigid element pivoted to the one outwardly extending arm but is preferably in the form of a toggle joint. The toggle joint may comprise a toggle arm rotatable on the one outwardly extending arm and pivotally supporting a locking arm which is capable of swinging into the curve of the other outwardly extending arm and wedging with the other arm in an undercentre condition. If the toggle joint is then forced, for example, by a hammer blow, into a slightly overcentre position, a greater prising force can be exerted between the outwardly extending arms to effectively provide a locking of the wedging means. Thus, preferably, - if the toggle joint is moved out of its overcentre position the wedging action of the coupler is maintained. The locking arm may only engage the aforementioned serrations or corrugations when it is forced into its overcentre position thereby facilitating the initial undercentre wedging action of the toggle joint. Thus, the locking arm may have an opening formed in it through which the other arm projects in the wedging condition and in the undercentre condition engages a smooth radially inner surface (relative to the pivot axis of the wedging means) of the other arm and the serrations or corrugations are formed on the radially outer surface of the other arm. Alternatively, the serrations or corrugations, if provided, may be on both the radially inner and outer surfaces of the other arm. The opening in the wedging means, for example the locking arm, may be formed by bending a portion of the wedging means out of its principal plane with the bent portion acting as a bearing surface for the other arm. Advantageously, means such as a stop is provided at the distal end of the other arm to restrict disengagement of the wedging means from the arm. Thus, if, for example, the wedging means is released by a lever action or a hammer blow, the stop will prevent the wedging means from releasing the other arm and thereby prevent the release of the rod held by the coupler other than possibly by a sliding action through the coupler. The wedging means may be prevented totally from disengaging the other arm. Each of the support means and saddle means may be formed in one part, for example by casting, but preferably the U-shaped support means comprises two spaced U-shaped members, which may be stamped out of plate steel and the saddle means is pivoted between the U-shaped members. The saddle means may also be U-shaped so as to at least partly receive the rod. A second coupler may be connected to the first mentioned coupler to form a double coupler if desired. The connection may be by the base of the support means of each of the couplers with, for example, the two support means interlocking. Alternatively, a plate may be provided at the base of one support means for connection, preferably by swivel means, to a similar plate on the second coupler. This plate and swivel method of connection allows for coupling of the two couplers at angles other than right angles. Yet another alternative is for the base of the support means to be welded to a scaffolding tube so as to allow connection of two scaffolding tubes using only one coupler or, in the case of the cast support means, for two support means to be integral in the casting. Other methods of connecting two couplers together may be readily envisaged. Various embodiments of a coupler in accordance with the present invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 is a side view of a first embodiment of coupler in accordance with the invention; Figure 2 is a view similar to Figure 1 but showing two modified couplers interconnected at right angles to one another; Figure 3 is an enlarged view of part of the embodiment in Figure 2 showing the wedging action of the coupler; Figure 4 is a view similar to Figure 1 but showing a further modification; Figure 5 is a partial view showing a yet further modification of the coupler; and Figure 6 is a view similar to Figure 5 but showing a still further modification. Many of the parts shown in the various figures are identical to or closely similar to corresponding parts in others of the Figures and for convenience will be given the same reference numeral where appropriate. Referring now to Figure 1 the scaffolding tube coupler 10 comprises a pair of spaced U-shaped support members 12 (one only shown in Figure 1 but compare Figure 2) each having a first leg 14 and a second leg 16. A pivot element 18 extends between the first legs 14 of the support members 12 and is welded or otherwise secured thereto to assist in retaining the support members 12 in spaced apart manner. Pivotally mounted on the element 18 is an inverted U-shaped saddle 20 which is crimped at one end 22 to form the pivotal mounting. The saddle 20 is pivotable about the element 18 between an open position (not shown) in which it is rotated anti-clockwise in Figure 1 to open the U-shape of the support member 12 and the closed position illustrated in which it closely overlies a scaffolding tube 24 received between the legs 14 and 16 and a base 26 of the support members 12. The support members 12 have a greater depth than is necessary merely to clamp the tube 24 between the bases 26 of the support members and the saddle 20, and this is . to accommodate the bases 26' of a second coupler 10' interlocked at right angles with the coupler 10. Only the bases 26' of the second coupler 10' are illustrated in Figure 1, but a similar arrangement will be described in detail with reference to Figure 2. The pair of support members 12 and the saddle 20 intersect at 28 (in the side view illustrated) to the side of the scaffolding tube 24 remote from the pivot element 18, and the second leg 16 of each support member 12 and the saddle 20 have outwardly extending arms 30 and 32 respectively which are forced apart (in the vertical direction as illustrated) by a toggle joint 34 to clamp the scaffolding tube 24 in the coupler 10. Each outwardly extending arm 30 of the support members 12 is crimped at 36 around a pivot arm 38 of a toggle member 40 so that the toggle member is pivotable relative to the support members 12. The toggle member 40 has a cross-member 42 on which a locking arm 44 is pivotally secured. At its end 46 remote from the cross-member 42, the locking arm 44 is tapered to a point which is capable of engaging serrations 48 in the opposed surface 50 of the outwardly extending arm 32 of the saddle 20. The upper surface 50 of the outwardly extending arm 32 is radiused about a point 52 which lies outwardly of the pivot arm 38 whereby the curved surface 50 effectively approaches the pivot axis of arm 38 with increasing distance from the distal end 54 of the outwardly extending arm 32. The serrations 48 are shown as only extending over part of the surface 50 of the outwardly extending arm 32 but they may be extended as desired. A stop 56 projects from the upper surface 50 at the distal end 54 of the arm 32 for a purpose which will be described hereinafter. The locking arm 44 is illustrated with an outwardly projecting portion 58 and in order to clamp the scaffolding tube 24 in the coupler 10, the projecting portion 56 is struck sharply with a hammer or similar device with the toggle joint 34 essentially iii the undercentre condition illustrated so as to force the tip 46 of the locking arm 44 across the serrations 48 in a direction away from the stop 56. This displacement of the locking arm across the serrations becomes increasingly difficult as the tube 24 is clamped more tightly, because of the offcentre radiused effect of the surface 50. In this clamped condition, the cross-member 42 is in the illustrated position 60 and the locking arm 44 is restrained from additional pivotable movement relative to the toggle member 40 in the clockwise direction by engagement of the projecting portion 58 with, for example, the stop 56. Although in the condition illustrated the 0 toggle joint 34 adequately clamps the tube 24 in the coupler 10, accidental release of the wedging action provided by the toggle joint may occur if the toggle joint is knocked or vibrated. In order to alleviate this possibility, the toggle joint may be moved from 5 the undercentre condition illustrated to the overcentre condition of the cross-member 42 illustrated in dashed lines at 62. Excess overcentre movement is prevented by engagement of the adjacent end of the locking arm 44 with the saddle 20 at about Q the intersection 28. In the overcentre condition shown at 62, the outwardly extending arms 30 and 32 of the support members 12 and the saddle 20 are urged even further apart to additionally clamp the tube 24. Movement of the toggle joint from the undercentre condition to the overcentre condition may be achieved by a hammer blow on the locking arm 44 at 64. Release of the tube 24 from the coupler 10 may be achieved by inserting a hammer claw between the locking arm 44 and the intersecting portions 28 of the support members 12 and saddle 20 and levering the toggle joint into the undercentre condition and then displacing the tip 46 of the locking arm anti-clockwise along the serrations. The stop 56 acts to prevent the locking arm 44 from jumping clear of the outwardly extending arm 32 of the saddle so that without manually fully releasing the locking arm the tube 24 may only be slidingly disengaged from the coupler. Indeed, a small clamping force may still be applied to the tube 24 when the tip 46 of the locking arm 44 abuts the stop 56. The support members 12, the saddle 20 and at least the toggle member 40 may be formed from circular rod but are conveniently stamped from plate steel so as to minimise production costs. As two hammer blows are sufficient to lock the coupler 10 about the scaffolding tube 24 and a simple tug with the hammer claw is all that is needed to release the coupler from the tube, it will be apparent that the coupler may present considerable savings of time and effort in both the installation and dismantling of scaffolding. In addition, the only tool necessary for erection and dismantling of the scaffolding is a hammer and it is not necessary to use spanners. Also, there are no parts to become dettached from the coupler with the resultant possibility of loss, and the overcentre toggle joint clamping arrangement provides very effective clamping of the tube. Referring now to Figure 2, the coupler 100 has a similar construction to the coupler 10 and will therefore only be described in detail in relation to its differences. The pivot element 118 is supported between the spaced support members 112 (only one shown) by engaging opposed openings 119 in the first legs 114 of the support members. Similarly, the pivotal engagement at 138 of the toggle member 140 in the outwardly extending arm 130 of the second leg 116 of the support members 112 is by engagement of a finger 137 of the toggle member in an opening 139 in the outwardly extending arm 130. The locking arm 144 off the toggle joint 134 comprises a plate which has a transverse cylindrical member 145 welded thereto to pivotally receive the cross-member 142 of the toggle member 140. The top edge 147 of the locking arm 144 abuts the toggle member 140 in the undercentre condition illustrated to define the maximum clockwise pivotal movement of the locking arm 144 relative to the toggle member 140. The locking arm 144 has an opening 146 formed therein in which the outwardly extending arm 132 of the saddle 120 is received in the closed condition of the coupler 100. In the undercentre condition illustrated, the upper and lower surfaces of the opening 146 extend substantially parallel to the corresponding surfaces 150 and 151 of the outwardly extending arm 132, thereby facilitating sliding movement of the locking arm 144 over the arm 132. The upper surface 150 of the arm 132 is essentially smooth and as the locking arm 144 is urged up the arm 132 away from the distal end 154, there is increasing resistance due to the offcentre axis 152 of the centre of curvature of the arm 132. The increasing resistance forces the saddle 120 to more tightly clamp the tube 124 in the coupler 100 and as in Figure 1, the coupler may be locked by forcing the toggle joint from the undercentre condition 160 illustrated to the overcentre condition 162 illustrated in dotted lines in Figure 2 which is the maximum clockwise angle of inclination of the locking arm 144 relative to the arm 132 of the saddle 120. The lower surface 151 of the arm 132 is serrated at 148 and in the overcentre condition 162 the lower surface of the opening 146 engages the serrations 148 to lock the locking arm 144. At the same time, the upper surface of the opening 146 remains in engagement with the upper surface 150 of the arm to define the maximum clockwise rotation of the locking arm 144 relative to the toggle member 140 and to therefore define the overcentre condition 162. This contrasting condition of the locking arm 144 is illustrated schematically in Figure 3 although it will be appreciated that during the movement of the toggle joint from the undercentre condition 160 to the overcentre condition 162 the outwardly projecting arm 132 is urged downwardly as shown generally in relation to Figure 4. The distal end 154 of the arm 132 includes a stop 156, but immediately adjacent the stop a recess 157 is formed in the upper surface 150 of the arm into which the locking arm 144 is adapted to drop when the locking arm is disengaged from the serrations 148 to prevent the locking arm from swinging loose from the outwardly extending arm 132. Figure 2 also illustrates in full the interlocking second coupler 100* which clamps a second scaffolding tube 124' perpendicularly to the tube 124. As in Figure 1, the interlocking is by virtue of the bases 126' of the spaced support members 112' of the coupler 100' extending between the tube 124 and the bases 126 of the support members 112 of the coupler 100. Likewise, the bases 126 of the support members 112 of the coupler 100 extend between the clamped tube 124' and the bases 126' of the support members 112' of the coupler 100'. The couplers 100 and 100' are identical so the coupler 100' will not be described in detail. However, Figure 2 clearly illustrates the spacing of 5 the support members 112' and the plate-like shape of the locking arm 144'. Additionally, the C-shape of the toggle member 140' is illustrated with the pivot fingers 137* disposed in corresponding openings 139' in the outwardly extending arms 130' of the 10 respective support members 112'. Referring again to the coupler 100 in Figure 2, the outwardly extending arm 132 may have any appropriate cross-section such as square or round, or rectangular as illustrated. The opening 146 in the 5 locking arm 144 will have a corresponding shape with a slightly greater height. The serrations 148 are entirely optional since it is found that the locking of the toggle joint 134 in the overcentre condition 162 and as illustrated in Figure 3 (but without the o serrations) is sufficient to maintain the clamping condition of the coupler. Nevertheless, the serrations 148, or similar formations, are preferred since they alleviate the possibility of the locking arm 144 disengaging the outwardly projecting arm 132 5 accidentally, for example, due to vibration or an accidental knock. The serrations or other formation may extend substantially the full length of the lower surface 151 of the arm 132. The coupler 200 in Figure 4 has a second Q coupler 200' (only the support members 212' thereof being shown) interlocked therewith and is substantially identical to the coupler 100. The support members 212 and the saddle 220 are stamped from plate steel and are pivotally interconnected by an element 218 which passes through appropriate openings 219 in the support members and a corresponding opening in the head 222 of the saddle 220. The flat section of the support members 212 is illustrated by reference to the support members 212'. In addition to these changes, the outwardly extending arm 230 of the second leg 216 of each support member 212 is rather more continuous than in the previously described embodiments and the pivotal connection 238 with the toggle joint 234 is by partial crimping (only shown schematically in the Figure) . The toggle joint 234 is identical to the toggle joint 134 in Figure 2 except that the opening 246 is formed by bending a portion 247 of the material of the plate-like locking arm 244 out of the plane of the plate and substantially perpendicularly to the plane. This portion 247 acts as an additional bearing surface of the arm 244 along the upper surface 250 of the outwardly projecting arm 232 of the saddle while the toggle joint 234 is in its undercentre condition 260,. thereby minimising wear. The bearing portion 247 does not affect the locking of the toggle joint 234 in the overcentre condition illustrated in dotted lines at 262. As noted already, in the overcentre locking condition of the toggle joint 234, the outwardly extending arm 232 is forced downwardly away from the arm 230 of each support member to additionally clamp the tube 224. This displacement of the arm 232 is illustrated in part in Figure 4. It will be noted in Figure 4 that the serrations 248 extend substantially the full length of the lower surface 251 of the arm 232. In the couplers 100 and 200, the respective stops 156 and 256 prevent the locking arm from jumping off the outwardly extending arm of the saddle when the toggle joint is released from its overlocking condition. However, it is possible by manipulating the locking arm relative to the stop to manually separate the locking arm and outwardly extending arm. In contrast to this, in Figure 5 the stop 356 is extended downwardly so as to prevent the locking arm 344 from being removed at all from the outwardly extending arm 332 of the saddle 320. Apart from this modification and the fact that the serrations 348 extend substantially the full length of the lower surface 351 of the arm 332, the coupler 300 (shown only in part with one interlocking support member 326') is substantially identical to the coupler 100. In Figure 6, the coupler 400 also shown only in part, is identical to the coupler 100 except that the optionally serrated outwardly extending arm 132 of the saddle 120 is replaced by a corrugated arm 432 incorporating a stop 456. The corrugations are defined on both the upper surface 450 and the lower surface 451 of the arm 432 and each corrugated surface 450 and 451 is defined by two alternating sets of intersecting arcuate portions 448 and 449 (which are each effectively planar) with the arcuate portions 448 having as their centre of curvature the pivot axis 437 of the toggle member 440. In contrast, the arcuate portions 449 have as their centre of curvature the outwardly offset axis 452. In the undercentre condition 460 of the toggle joint 434, the upper surface of the opening 446 in the locking arm 444 rides over the arcuate portions 449 as the clamping on the tube is tightened by forcing the locking arm 444 away from the distal end 454 of the arm 432. When the toggle joint 434 is moved to its overcentre condition (not shown) by a striking blow at 464, the upper surface of the opening 446 in locking arm 444 pivots into alignment with the adjacent arcuate portion 448 on the upper surface 450 of the arm 432. Thus, the locking arm must slide up the engaged arcuate portion 448 to release the tube without being displaced out of the overcentre condition, so, the coupler 400 is most unlikely to release the clamped tube due to vibration of the coupler. As in previous embodiments, release of the tube is by moving the toggle joint 434 into the undercentre condition and sliding the locking arm 444 outwardly over the arm 432. It will be understood that many modifications and variations may be made to the described embodiments of the invention without departing from the spirit and scope of the invention as defined by the accompanying claims. In particular, it will be understood that the coupler of the invention may be used to connect two scaffolding tubes, or other rods, arranged end-to-end, using a sleeve-type end-to-end coupler, a bolt extending through two plates of the coupler and connected positively to a third plate, the toggle joint or other wedging means acting to force the third and middle plates apart to thereby tighten the end-to-end coupler on the two scaffolding tubes.

Claims: CLAIMS : 1. A rod coupler comprising U-shaped support means adapted to at least partly receive a rod, such as a scaffolding tube, between the legs of the U-shape, saddle means pivoted adjacent one end to one of the legs of the support means for movement between a position in which the saddle means extends across the legs of the support means to be clamped over a rod received by the support means and a position in which the rod can be withdrawn from the support means, the support means and the saddle means intersecting to the side of the rod remote from the pivot in the clamping position, the other leg of the support means and the other end of the saddle means defining respective outwardly extending arms, and wedging means pivoted to one of the outwardly extending arms and adapted in the clamping position to engage the other outwardly extending arm to the distal side of the intersection to force the arms apart and thereby clamp the coupler around the rod. 2. A rod coupler according to Claim 1 wherein the U-shaped support means comprises two U-shaped members and the saddle means is pivoted between the U-shaped members. 3. A rod coupler according to Claim 1 or Claim 2 wherein the saddle means is also U-shaped so as to at least partly receive the rod. 4. A rod coupler according to any one of Claims 1 to 3 wherein the wedging means is pivoted on the support means. 18 5. A rod coupler according to any one of the preceding claims wherein said engagement of the wedging means is with a radiused portion of said other arm whose centre of curvature is offset outwardly from the pivot axis of the wedging means. 6. A rod coupler according to any one of the preceding claims wherein said engagement of the wedging means is with a serrated portion of the other arm. 7. A rod coupler according to any one of claims 1 to 5 wherein said engagement of the wedging means is with a corrugated portion of the other arm, each corrugation being defined by two arcuate parts, a first part of which has its arcuate centre of curvature at the pivot axis of the wedging means and a second part of which has its centre of curvature offset outwardly from said pivot axis. 8. A rod coupler according to any one of the preceding claims wherein said other arm includes means at its distal end to restrict disengagement of the wedging means from the arm. 9. A rod coupler according to Claim 8 wherein the wedging means is prevented from disengaging the other arm. 10. A rod coupler according to any one of the preceding claims wherein the wedging means comprises a rigid element. 11. A rod coupler according to any one of the preceding claims wherein the wedging means comprises a toggle joint. 12. A rod coupler according to Claim 10 or Claim 11 wherein the wedging means has an opening therethrough through which the other arm projects. 13. A rod coupler according to Claim 12 wherein the opening is formed by bending a portion of the wedging means out of its principal plane, said bent portion acting as a bearing surface for the other arm.

Inventors: ROBINSON DONALD SCOTT, ROBINSON, DONALD, SCOTT
Applicants: ROBINSON DONALD SCOTT, ROBINSON, DONALD, SCOTT
Application year: 1988
Main classification: E04G7
IPC codes: E04G7, F16B2, F16B7