1952-11-26

Abstract of GB683386 683,386. Furniture joints. EVANS, O. J., :and McCONNEL. J. K. March 17, 1950 [March 21. 1949; April 13, 1949], Nos. 7625/49 and 10014/49. Class 52(ii) [Also in Groups X and XXVIII] A device for connecting a tube 52 to an intermediate point in the length of a tube 50 comprises a cylindrical plug 56 shaped at one end to embrace the tube 50 and provided at the other end with a reduced spigot to receive the tube 52, and a bolt 58 extending axially through the plug and through a hole in the tube 50 to engage its head 60 with the interior of the tube. The joint is particularly applicable to tubular furniture. The tube 52 is secured by a grub-screw 65 in the plug operated by a tool through a hole 53 smaller than the grub-screw which is unscrewed so as to bear against the internal surface of the tube. The bolt-head has a conical surface 64 whereby the material of the tube 50 is expanded against the conical seat 63. The bolt-head is introduced through a key-hole slot 51, Fig. 11, and is prevented from slipping by a tongue 69. Alternatively the position of the bolt is reversed so that the nut 62 is within the tube 50. In another form the bolt-head is passed through a circular opening 151, Fig. 20, and is held by a bush 80 which is pushed down the tube 50 so that a slot 81 therein engages the shank of the bolt. The bolt is first screwed into the plug so that it projects a sufficient distance and is then locked by the nut 62. It is centred in the opening by a bush 82.

9

1952-11-26

F16B7/04 ; F16B7/04

F16B7/04D2

GB19490007625 19490321

GB19490007625 19490321

1	A new or improved connector for use in joining tubes
	Inventor:	Applicant: OWEN JOHN EVANS; JAMES KENNETH MCCONNEL
	EC:F16B7/04D2	IPC: F16B7/04;F16B7/04
	Publication info: GB683386 A - 1952-11-26

1	PIPE CONNECTION
	Inventor: BOEHL HARALD (DE)	Applicant: HABOE EDELSTAHL SYSTEME GMBH (DE); BOEHL HARALD (DE)
	EC:E04F11/18F2P; F16B7/04D2	IPC: E04F11/18; F16B7/04;E04F11/18(+3)
	Publication info: WO2004076869 - 2004-09-10
2	Keyhole slot attachment
	Inventor: MILLER MARVIN HERBERT; HOPTRY DAVID ALLEN	Applicant: GEN MOTORS CORP (US)
	EC:B60R11/00; B62D27/06A; (+1)	IPC: F16B35/04; B60R11/00; B62D27/06(+11)
	Publication info: GB2316708 - 1998-03-04
3	Mounting bolts
	Inventor: SPURR NIGEL	Applicant: ROCKWELL BODY & CHASSIS SYST (GB); ROCKWELL LVS (GB)
	EC:E05B9/08; E05B65/12C1; (+2)	IPC: E05B9/08; E05B65/12; F16B21/09(+8)
	Publication info: GB2302125 - 1997-01-08
4	Handrail assembly
	Inventor: TERRELS ANDREW P (US); MYERS JR EDWARD L (US)	Applicant:
	EC:B21D39/04C; E04F11/18F2	IPC: B21D39/04; E04F11/18;B21D39/04(+2)
	Publication info: US5370368 - 1994-12-06
5	Plastic security handrail system and connectors therefor
	Inventor: ZULICK III JAMES E (US); APPLER WILLIAM F (US)	Applicant: ZULICK III JAMES E (US); APPLER WILLIAM F (US)
	EC:E01F13/02C; E04F11/18F	IPC: E01F13/02; E04F11/18;E01F13/00(+2)
	Publication info: US5303900 - 1994-04-19
6	COUPLINGS
	Inventor: DONARTE NICHOLAS TONI PIERRE (GB)	Applicant: DONARTE NICHOLAS TONI PIERRE (GB)
	EC:E06B3/968F; F16B7/04D2; (+4)	IPC: E06B3/968; F16B7/04; F16B12/22(+15)
	Publication info: WO9213201 - 1992-08-06
7	Connector
	Inventor: GROOCOCK JOHN STUART	Applicant: COSBY MECHANICAL LIMITED (GB)
	EC:E04F11/18F2; F16B7/04; (+1)	IPC: E04F11/18; F16B7/04; F16B7/18(+4)
	Publication info: GB2215424 - 1989-09-20
8	Device for assembling two crossed tubular elements
	Inventor: SIMIER MICHEL; TONNERRE JACQUES	Applicant: JACCARD ITH SA (FR)
	EC:F16B7/04D2; F16B12/36	IPC: F16B7/04; F16B12/36;F16B7/04(+2)
	Publication info: FR2582752 - 1986-12-05
9	Joints between hollow elongate members
	Inventor: RAWLINGS DAVID EDWARD	Applicant: CONSORT ALUMINIUM LTD
	EC:E06B3/968F	IPC: E06B3/968;E06B3/96; (IPC1-7): E06B3/05
	Publication info: GB2119890 - 1983-11-23
10	Knotenverbindung fuer raeumliche Fachwerke
	Inventor: CHAMAYOU GERARD	Applicant: VALLOUREC LORRAINE ESCAUT
	EC:E04B1/58C2C; F16B7/04; (+3)	IPC: E04B1/58; F16B7/04; F16B12/32(+4)
	Publication info: DE1282279 - 1968-11-07

What we claim is: -

1. A connector of the type specified, 120 wherein the spigot portion carries a screw which may be screwed outwardly from the spigot to abut against the inner wall of a tube fitted over said spigot portion to secure said tube to said spigot portion. 125 2. A connector as claimed in Claim 1, in which the seating has a central recess into which the head of the bolt may be drawn as the bolt moves to clamping position.

3. The combination, with a first cylinconnector 54 is thus safeguarded against shifting in relation to the tube 50 under vibration or shock or as the result of any distortion of the walls of the keyhole slot 51 which may occur as the result of repeated tightening and slackening of the bolt.

An alternative form of tongue 169 is shown in Figs. 16-19, this tongue 169 being produced by forcing the material of the tube outwardly to form a dimple at the larger end of the keyhole slot 51.

The connector is preferably made of metal, but it could be made of other suitable rigid materials if desired. Where it is desired to provide for the passage of electric leads, or of liquid, from one tube to the other, this may be achieved by drilling a throughgoing passage in the body of the connector, appropriate packing being provided in the latter case to ensure a liquid-tight joint.

Mention has been made of the fact that the connector according to the invention is of particular utility for joining together the component tubes of tubular metal furniture.

The usual practice is to unite the component tubes by welding, which tends to affect adversely the flexibility and elasticity of the framework of the chair or other piece of furniture. Moreover, a welded tubular framework is bulky, whereas it is a desideratum that the constituent parts of the framework should be readily detachable so that they may be packed compactly in cartons or other packages for transport by road, rail or ship. The connector according to the invention fulfils this requirement and permits of rapid and easy erection of the framework, when desired, by unskilled labour.

In all of the forms so far described, the connector is engageable with a keyhole slot in the tVbe 50 so that the user may readily attach it to and detach it from that tube.

The keyhole slot is not, however, essential, provided the connection between the connector and the tube 50 is such as to produce no projecting excrescences. Thus the bolt 28 may be engaged, through a circular hole in the tube 50, with a nut or the like within the tube. With this construction, if there is a clearance between the bolt and the hole, some degree of circumferential positioning of the connector in relation to the tube 50 will be permissible, which may be of advantage in tubular furniture. The connector will, in this case, normally be assembled with the tube in the factory, leaving the user only to fit, by means of the grub screw, the other tube to the projecting spigot end of the connector.

Where the bolt 58 engages a nut located within the tube 50, the head of the bolt will of course be at the spigot end 55 of the connector. It may be engaged with a nut inside the tube 50 by sliding a procession 683,386 drical tube having therein a keyhole slot, of a second cylindrical tube extending at right angles to the first tube and locked rigidly thereto by a connector as claimed in Claim 1 or Claim 2, said second tube having therein a hole for passage of a screwdriver for screwing outwardly the screw on the spigot portion of the connector.

4. A combination as claimed in Claim 3, wherein the first tube has an outwardly projecting tongue adjoining the larger end of the keyhole slot and aligned with the narrow portion thereof, said tongue abutting against the outer face of the plug.

5. The combination, with a first cylindrical tube, of a second cylindrical tube extending at right angles to the first tube and locked rigidly thereto by a connector as claimed in Claim 1 or Claim 2, the bolt being accommodated in an axial bore in the plug with its shank extending through a hole in the first tube of size sufficient to pass the bolt head, a nut being provided on the end of the bolt remote from the seating and a retaining device being provided within the first tube and engaging the shank of the bolt beneath the bolt head to prevent withdrawal of the bolt through the hole.

6. A combination as claimed in Claim 5, comprising a sleeve accommodated in the axial bore in the plug and surrounding the bolt, said sleeve fitting into the hole in the first tube and bearing against the perimeter of the hole.

7. The combination, with a first 'cylindrical tube, of a second cylindrical tube extending at right angles to the first tube and locked rigidly thereto by a connector as claimed in Claim 1 or Claim 2, the bolt being accommodated ini an axial bore in the plug with its shank extending through a hole in the first tube of size sufficient to pass the bolt head, said bolt being in screw-threaded engagement with the bore in the plug, and a retaining sleeve being provided within the first tube fitting tightly between the bolt head and the tube and having a longitudinal slot, through which said shank passes and which is of less width than the head of the bolt, the retaining sleeve serving to prevent withdrawal of the bolt through the hole in said first tube.

8. A connector for joining together two tubes, substantially as described herein with reference to Figs. 1-9 of the accompanying drawings.

9. A connector for joining together two tubes, substantially as described herein with reference to Figs. 20 and 21 of the accompanying drawings.

BREWER & SON, Chartered Patent Agents, 5-9, Quality Court, Chancery Lane, London, W.C.2.

PROVISIONAL SPECIFICATION.

No. 7625, AD. 1949.

A:New or Improved Connector for Use in oining Tubes.

We, OWEN JoHN EVAL'S, of Goldwell, Great Chart, Nr. Ashford, Kent, and JAMES KENNETH MCCONNEL, of 51 Kings Road, Horsham, Sussex, both British Subjects, do hereby declare the nature of this invention to be as follows:This invention has for its object to provide a connector for use in clamping together two tubes extending at an angle to one another 7( which can be easily fitted to the tubes which will hold them firmly together and which, when in position, does not present any projecting excrescences.

The connector according to the invention comprises a cylindrical plug having at one end a seating shaped to embrace one of the tubes, a bolt housed in an axial bore in the plug, the head of the bolt being at the seating end of the plug and its threaded end proRG jecting from the other end of the plug and having a nut on it, and a grub screw in a radial hole in the plug.

In use, the seating is placed against the wall of one of the tubes and the head of the bolt introduced into a keyhole slot in that tube. The plug is then slid along the tube to bring the bolt into the narrow part of the slot and the nut tightened, so clamping the plug firmly to the tube. The other tube is then slipped over the plug to bring a hole, 901 slightly smaller than the head of the grub screw, opposite the grub screw. The grub screw is then unscrewed slightly, thereby fixing the other tube to the plug.

The plug, which is preferably of metal, 95 may conveniently be made by die casting.

In one -specific embodiment of the invention the connector consists of a cylindrical plug of such diameter that it will fit closely within one of the tubes. The plug is en- 10( larged in diameter at its end, the external diameter of the enlarged portion being equal to the external diameter of the tube just mentioned. The enlarged head of the plug is formed with a concave seating in which 105 the other tube may rest.

A bolt is fitted in an axial unthreaded bore in the connector. The seating is so shaped that, when the connector is approached to the other tube and the head of 110 -693,38.6 683,386 the bolt is engaged in the key hole slot, two diametrically opposite jaws of the seating abut against opposite sides of the other tube, the base of the seating being just clear of the tube. As the nut fitted to the projecting end of the bolt is tightened, the jaws deform the material of the tube and the connector is thus held very securely to it.

A grub screw is accommodated in a radial threaded bore in the smaller diameter portion of the connector. When the first mentioned tube is slipped over the plug, after connection of the plug to the other tube, the grub screw is slightly unscrewed to force its head into a hole in the first tube which is slightly smaller than the head of the grub screw, the hole being so located that, when secured to the connector the end of the first tube abuts against the head of the connector.

When the tubes are to be joined at right angles, the centre of curvature of the seating will lie on the extension of the axis of the connector. The smaller diameter portion of the connector may, however, be inclined to the head portion, if it is desired that the tubes should be connected at an angle other than a right angle. The face of the head which abuts against the end of the first tube will then be appropriately inclined to the axis of the head portion. The face of the head of the bolt which abuts against the inner wall of the other tube should then be inclined at the same angle to the axis of the bolt so as to give a sufficient bearing surface against the tube. Alternatively a washer with a suitably inclined face can be used under the head of the bolt.

The connector is especially useful for joining parts of tubular furniture. It presents a very neat appearance, since the only part visible is the head which appears to be a continuation of the tube into which the plug is fitted. Two grub screws at right angles may be provided in the plug, that being chosen for use which, when the chair or other article of furniture is completed, will face inwardly and therefore not be visible.

The connector has, however, many other uses, e.g. for joining scaffold poles and in the construction of tubular metal roof trusses, hoists, cranes, bridges, portable tripods and drilling derricks. As the connector has no external parts except for the head, it is largely protected from rusting by exposure to weather.

The bolt may be hollow to allow of the passage of electric cables through it for instance when the device is employed for joining tubs carrying such cables, or to allow of the passage of liquids and gases through the connector. In the latter case an appropriate packing will be provided between the seating and the tube resting in the seating so as to obtain a liquid or gas tight joint.

Dated this 21st day of March, 1949.

BREWER & SON, Chartered Patent Agents, 5-9, Quality Court, Chancery Lane, London, W.C.2.

PROVISIONAL SPECIFICATION.

No. 10014, A.D. 1949.

A New or Improved Connector for use in Joining Tubes.

We, OwEN JoHN EvANs, of Goldwell, Great Chart, Nr. Ashford, Kent, and JAMEs KENNETH MCCONNEL, of 51 Kings Road, Horsham, Sussex, both British Subjects, do hereby declare the nature of this invention to be as follows:In Application No. 7625/49 we have described a connector, for clamping together two tubes which extend at an angle to one another, comprising a cylindrical plug having at one end a seating shaped to embrace one of the tubes, a bolt housed in an axial bore in the plug, the head of the bolt being at the seating end of the plug and its threaded end projecting from the other end of the plug and having a nut on it, and a grub screw in a radial hole in the plug.

In use, the seating is placed against the wall of one of the tubes and the head of the bolt introduced into a keyhole slot in that tube. The plug is then slid along the tube to bring the bolt into the narrow part of the slot and the nut tightened, so clamping the plug firmly to the tube. The other tube is then slipped over the plug to bring a hole, slightly smaller than the head of the grub 90 screw, opposite the grub screw. The grub screw is then unscrewed slightly, thereby fixing the other tube to the plug.

The seating of the connector has a central recess and we find that, as the nut is 95 tightened on the bolt, the head of the bolt tends, by exerting pressure on the portions of the inner wall of the tube adjacent the keyhole slot, to distort the tube outwardly to some extent into the recess. The wall of 100 the tube is least stiff in the vicinity of the shoulder between the enlarged and the narrow parts of the keyhole slot, and as the nut is tightened and the distortion of the tube increases, each portion of each wall of 105 the slot is displaced into the recess to an extent proportional, or approximately so, to its distance from the edge of the recess, the maximum displacement being at th shoulder.

After the first tightening up of the nut and consequent slight distortion of the tube wall,- this distortion will persist, so that on any- subsequent re-assembly and tightening.

of- the nut, there could under certain circumstances, and- unless due care was taken, be a tendency for the bolt and bolt-head together with the whole anchorage assembly to slip along the distorted walls of the slot towards -the shoulder, and therefore towards -the large end of the keyhole slot. The dimensions bf the distortion and shifting movenent of the assembly will, of course, be extremely small, but they could be enough to -upset truly correct precision assembly which might be important. There are other -causes from which a similar lateral shift of the assembly could arise, e.g. breakage -of the bolt, slackening -of the nut, or vibration, especially if of certain critical or resonant frequencies.

According to the present invention, any tendency of the connector to shift laterally in relation to the tube embraced by the seating is obviated by so disposing the keyhole slot in- the tube -that it extends axially and that, when the connector is bolted to the tube, the enlarged part of the keyhole slot extends tangentially to the seating on the connector, while, at the same time, the bolt is abutting against the end of the narrow -portion- of the- slot. A narrow axially ex-tending tongue is sheared in the wall of the tube, this tongue terminating at the enlarged part of the slot and being lifted so that its end stands slightly proud of the tube. The raised ends of the tongue will then abut against the outer wall of the- connector when the latter is in operative position and so render it impossible for the bolt to shift towards the enlarged part of the keyhole slot.

It cannot, of course, shift in the other direction because it abuts against the end of the narrow part of the slot. Any tendency of the connector to shift as the result of the above-mentioned distortion of the tube is thus entirely obviated.

Dated this 13th day of April, 1949. BREWER & SON, Chartered Patent Agents, : - - London, W.C.2.

Abingdon: Printed for Her Majesty's Stationery Office,by Burgess & Son (Abingdon), Ltd.-1952.

Published at The Patent Office, 25, Southampton Buildings, London, W.C.2, from which copies may be obtained.

-683,1386

RES -"'

PATENT SPECiFICATION 683,3J

Date of filing Complete Specification (under Section 16 of the

Patents and Designs Acts, 1907 to 1946): March 17, 1950.

Application Date: March 21, 1949. No. 7625/49.

a Application Date: April 13, 1949. No. 10014 /49.

Complete Specification Published: Nov. 26, 1952.

Index at Acceptance:-Classes 20(ii), C3c3, F3c; 52(ii), W2(i: j); and 99(i), G(7:12: 33).

COMPLETE SPECIFICATION.

A New or Improved Connector for Use in Joining Tubes.

We, OWEN JOHN EVANS, of Goldwell, Great Chart, nr. Ashford, Kent, a British Subject, and JAMES KENNETH MCCONNEL, of 51 Kings Road, Horsham, Sussex, a British Subject, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:-

This invention relates to connectors, for use in clamping together two tubes extending at an angle to one another, of the type comprising a cylindrical plug formed at one end with a seating, shaped to embrace one of the tubes and including jaws for abutting against opposite sides of said tube, and having at the other end a cylindrical spigot portion of reduced diameter, to fit closely within the end of the other tube and adapted to be secured to said other tube, and a bore extending more or less axially through the plug and serving to receive a bolt which may be inserted into a hole in the first-mentioned tube to clamp the connector to said tube.

Such connectors are made in sizes appropriate to the sizes of the tubes to be joined, the spigot portion being of external diameter equal to the internal diameter of the tube within which it is to fit, the remainder of the plug having the same external diameter as that tube so that it will constitute an unbroken continuation of the outer wall of that tube when the spigot portion is in position therein and the radius of curvature of the seating being appropriate to the radius of the tube to be embraced by the seating.

The invention provides a connector of the above type, wherein the spigot portion carries a screw which may be screwed outwardly from the spigot to abut against the inner wall of a tube fitted over said spigot portion to secure said tube to said spigot portion.

Certain embodiments of the invention will now be described in detail, by way of exr}_ ample, with reference to the accompanying drawings, in which: Fig. 1 is a perspective view of one form of connector for joining two tubes at right angles, one of the tubes being shown joined to the connector and being partly broken away; Fig. 2 is a part perspective view of the other tube; Fig. 3 is an end elevation of the connector; Fig. 4 is a perspective view of the connector with one of the tubes connected to it; Fig. 5 is a part sectional view through the connector and one of the connected tubes, showing the bolt fully tightened; Fig. 6 is a sectional view through the connector and the two tubes, but with the bolt not fully tightened; Fig. 7 is a section on the line 7-7 in Fig. 3; Figs. 8 and 9 are respectively sections on the lines 8-8 and 9-9 in Fig. 6; Fig. 10 is a longitudinal section through an alternative form of connector; Fig. 11 is a corresponding end elevation; Fig. 12 is a section on the line 12-12 in Fig. 10; Fig. 13 is a section through the end part of the connector of Figs. 10-12 showing the same attached to a tube provided with a locking tongue; Fig. 14 is a section, on the line 14-14 in Fig. 13, showing the tube only, Fig. 15 is a section on the line 15-15 in Fig. 14; Figs. 16-18 are views, corresponding respectively to Figs. 13-15, showing the connector used in conjunction with a tube having a different form of locking tongue; Fig. 19 is a perspective view of part of the tube shown in Figs. 16-18; Fig. 20 is a sectional view showing two r. ao0 tubes joined by an alternative form of connector; and Fig. 21 is a section on the line XXIXXI in Fig. 20.

Like reference numerals designate like parts throughout the Figures.

Considering first Figs. 1-9, the connector there shown is used for joining together two tubes at right angles, one of the tubes 50 having therein a keyhole slot 51 and the other tube 52 having therein a circular hole 53. The connector 54 comprises a cylindrical plug, having a reduced spigot portion 55 adapted to fit closely within the tube 52 and having an enlarged cylindrical head 56, the external diameter of which is equal to the external diameter of the tube 52.- The head 56 of the connector is formed with a partcylindrical seating recess 57 (Fig. 4) shaped to fit the other tube 50.

A bolt 58 (Fig. 6) is fitted in an axial unthreaded bore 59 (Fig. 4) in the connector.

The seating 57 is so shaped that, when the connector 54 is approached to the tube 50 and the head 60 of the bolt is engaged in the keyhole slot 51, two diametrically opposite jaws 61 of the seating abut against opposite sides of the tube 50. After the head 60 of the bolt has been engaged in the wider part of the keyhole slot 51, the connector 54 is slidden longitudinally of the tube to move the shank of the bolt 58 up to the end of the narrower part of the keyhole slot as indicated in Fig. 1. A nut 62 (Fig.

6) fitted to the other end of the bolt is then tightened so as to approach the bolt head 60 to a conical countersink 63 in the recess 57 of the anchorage. The result is to deform the material of the tube 50, the material being gradually drawvn down into a position between the bolt head 60 and the countersink 63 as shown in Fig. 5. Preferably the inner face 64 of the bolthead is shaped to conform with the shape of the countersink 63 as shown. The jaws 61 may likewise exercise some deforming action on the material of the tube 50 and, due to this and to the deformation of the tube by the bolt head 60 as shown in Fig. 5, the tube 50 is held very securely to the connector 54.

A grub screw 65 is accommodated in a radial threaded bore 66 (Fig. 7) in the smaller diameter spigot portion 55 of the connector. When the tube 52 is slipped over the spigot 55, after connection of the connector 54 to the tube 50, the grub screw is slightly unscrewed by insertion of a tool, through the hole 53 in the tube 52, into a recess 67 in its head, to draw its head outwardly into firm engagement with the inner wall of the tube 52. The hole 53 is so located that, when secured to the connector, the end of the tube 52 abuts against the head 56 of the connector as clearly shown in Fig. 6. As the result of this operation the material of the tube 52 is slightly deformed, by reason of the pressure of the grub screw against its inner wall, as shown greatly exaggerated in Fig. 9. A secure clamping of 70 the tube 52 to the connector is thus achieved.

As indicated in Figs. 1, 7 and 9, two threaded holes 66 may be provided in the spigot 55, these holes extending at right angles to one another and each capable of 75 accommodating a grub screw 65. The connector according to the invention is of special utility and value for connecting together the component tubes of tubular metal furniture. In use, it presents a very 80 neat appearance since, when in effective position, the only part visible is the head 56 which appears to be a continuation of tube 52 as shown in Fig. 6. It is desirable, for this specific use of the connector, to provide 85 two grub screws 65 in order that that one may be chosen for use which, when the chair or other article of furniture is erected, will face inwardly and therefore not be visible.

The connector has, however, many other 90 uses, e.g. for joining scaffold poles and in the construction of tubular metal roof trusses, hoists, cranes, bridges, portable tripods and drilling derricks. As the connector has no external parts except for the head, it 95 is largely protected from rusting by exposure to weather.

The connector shown in Figs. 10-12 is identical with that of Figs. 1-9, except that the conical countersink 63 of the previous 100 embodiment is replaced by a recess 163 formed by a shallow depression which duplicates; at a lower level, the cylindrical surface of the recess 57. A line drawn along the base of the recess 163 in the plane 105 shown in Fig. 10 will be a straight line, while a similar line in the plane of Fig. 12 will be an arc of a circle.

It may be in some cases desirable to provide in the tube 50, at the end of the larger 110 portion of the keyhole slot 51 and opposite the narrow portion of said slot a- projecting tongue 69, as shown in Figs. 13-15. The tongue, as there shown, is formed by cutting two axially extending slits 70 in the wall of 115 the tube, these slits being open to the slot 51, and pressing the material between them upwards as shown at 69 so that it stands slightly proud of the tube.

The end of the tongue 69 will then abut 120 against the outer wall of the part 56 of the connector, when the latter is in operative position, and so render it impossible for the bolt, accommodated in the bore 59 of the connector, to shift towards the enlarged part 125 of the keyhole slot 51. The bolt cannot, of course, shift in the other direction because, when in operative position, it abuts against the end of the narrow part of the slot 51, as indicated in Fig. 14 and also-in Fig. 8. The 130 683,386 of nuts along the tube and picking one of them up by the bolt.

Figs. 20 and 21 show an alternative retaining device within the tube 50, for preventing withdrawal of the bolt through a 70 circular hole 151 in the tube 50 of bore sufficient to pass the head 60 of the bolt. This retaining device is constituted by a sleeve 80, which is a friction fit within the tube 50 and has an axial slot 81 open to one end of the 75 sleeve. In this case the bore in the connector is threaded and the bolt is first set to project by the correct amount from the seating end of the connector and locked in that position by the nut 62. The sleeve 80 is then pushed 80 along the tube to engage its slot 81 around the shank of the bolt, as shown in Fig. 20, the sleeve 80 then fitting tightly between the bolt head 60 and the tube 50 and holding the bolt securely in position and preventing its 85 withdrawal through the hole 151 in the tube 50. A sleeve 82 is positioned within the axial bore in the plug around the bolt 58, and fits closely within the hole 151 in the tube 50, as shown. 90 In all of the constructions shown, the tubes 50, 52 joined by the connector exfend at right angles to one another, the centre of curvature of the seating 57 of the connector, which receives the tube 50, being 95 located on an extension of the axis of the connector. In cases where it is desired that the two tubes should not extend at right angles, the seating will be appropriately shaped and its centre of curvature will be 100 offset from the axis of the connector. In these cases, since the axis of the bolt will not extend at right angles to that of the tube 50, it is desirable to provide beneath the head of the bolt a washer shaped so as to 105 give, when the bolt is tightened,' bearing pressure over a substantial area of the inner face of the tube 50. Alternatively, the washer can, in effect, be made unitary with the head of the bolt. 110 Again, while in all the constructions shown the bolt 58 is located coaxially within the plug it may, in some cases, be desirable to incline the bolt at a small angle, e.g. up to about 100. to the axis of the plug so that 115 the bolt will lie more or less in the position towards which the bending loads on the joint tend to displace it.