AU712124B2 - Adjustable hollow arm and joints therefor - Google Patents

Description

I/O 'I Il 1..,.71 ADJUSTABLE HOLLOW ARM AND JOINTS THEREFOR This invention relates to a adjustable hollow arm and joints therefor to form a dust or fume extractor for a range of applications such as the removal of energy or matter or motion from a selected work area or machine; including; the removal of pollutants such as gases, liquids or solids.

BACKGROUND OF THE INVENTION The removal of polluting and harmful substances from work areas by the positioning of flexible, movable and adjustable arms is well known. Examples are flexible hoses of corrugated form which are supported and positioned as 1 0 desired. However these require some additional supporting mechanism, usually in the interior or on the exterior of the hose. Also the hose, by also having an internal corrugated surface provides a restriction to the flow of the fluid therethrough, and also collects dirt and other polluting materials in the internal folds and corrugations. Also the material of the flexible hose, in order 1 5 to be flexible is subject to abrasion, corrosion, slitting, puncturing and damage.

Arms which are of semi-solid construction have flexible angle joints connecting solid portions of the arm, the flexible joints comprising flexible hoses or bellows joining the solid portions of the arms. The arms are connected by hinges, either externally or internally of the flexible hose. Often the arm itself is supported by an external linkage and spring arrangement so that the arm can be adjusted and positioned as desired. In other instances the supporting linkage is positioned within the arm and joints, but in such a position offers a restriction to the fluid flow therethrough, collects materials thereon, and can be subject to corrosion depending on the material passing through the hollow arm. Examples of these forms of adjustable arms are shown in US 5336130, US 4860644 and DE 4133757.

Also it is known for solid arms to be connected by solid angle joints, each joint being of two portions having a right angled bend. Thus each solid portion of the arm is offset from its adjacent portion, and the air stream in passing through the joint has to make two right angled turns. While this construction eliminates the corrugated flexible joint, there is still the disadvantage of the i resistance to the air flow due to the air having to make two right angled turns at

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2 each joint of the arm. Also, it is difficult for long arms to be constructed in this manner, due to the strength and twisting/torsional problems in the vicinity of the two right angled bends. An example of these forms of arms are shown in US 5336130.

While the arms can be positioned in the vicinity desired, it is also desirable to have a fitting attached to the end of an arm which fitting can be positioned relative to the arm in as many positions as possible. This is particularly desirable when the arm is provided for the extraction of pollutants from a particular work area, and it is appreciated that a universal type joint is 1 0 particularly suitable for this purpose, such as a member which is attached to a ball or spherical member is desirable.

One unit which has a universal type connection for the flow of fluid therethrough is a ventilation unit as described in DE 732070 where a nozzle is attached to a spherical member, which spherical member is rotatable through 1 5 3600 in a mounting member. However the hood or nozzle attached to the spherical member is round or conical where it joins the spherical member.

Thus its intersection to the spherical member is an ellipse or an asymmetrical ellipse (egg shaped) and results in a low ratio of its throat area (opening area where the hood joins the ball) to the cross sectional area of the ball. This results in a large pressure drop occurring for any fluid passing through the unit. As described the unit is a ventilation unit where air exits in the hood and thus any pressure drop is of no great consequence, and the direction and positioning of the hood is not critical.

An example for the extraction of air or a fluid is a universal joint comprising flexible hose with an internal or external supporting mechanism being two axes in the form of a cross with a bearing on each axis. However this style of joint requires flexible hose which provides a restriction to the flow of fluid therethrough, collects dirt in its corrugations and is subject to abrasion, corrosion and damage. A further example is a universal joint comprising a nozzle connected to a hollow ball in a socket. Such orbital nozzles are used for cabin ventilation in passenger transport or for ceiling lighting. However this style of joint has only a limited range of movement, for example over a quarter of a sphere and thus cannot be directed to as many positions as desired.

It is an object of the invention to provide joints or fittings which can be moved AME".voA

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q~PZ- /Au 3 relative to supports to which they are attached, whether this be an adjustable arm or other structure, which overcomes one or more disadvantages of known joints such as the presence of flexible hose or the limited range of movement or the need for two right angled changes of direction at the joint or a high pressure drop caused by a small throat area when the hood joins the ball.

It is a further object of the invention to provide an adjustable arm having at least one joint which will overcome one or more of the disadvantages of the 1 0 known arms.

BRIEF STATEMENT OF THE INVENTION Otto Thus there is provided according to the invention a dust or fume extractor, said too:" extractor including a hollow hood on a universal joint connection to a hollow arm, said joint including a holding frame, a hollow part spherical member 1 5 positioned within said frame, said part spherical member being recess mounted in said frame to provide an exposed face of the part spherical member and a recessed surface, said hollow hood attached to said exposed to.. face of the part spherical member asymmetrically offset from the centre of the said exposed face, said hood having two walls where it joins the part 2 0 spherical member, a first of said walls being flat and positioned to extend normal from said exposed face along or adjacent to diametrical line of said S: part spherical member, a second of said walls being curved and positioned opposite said first wall to extend from said exposed face to extend from a chord of said part spherical member, said chord diverging from the first wall 2 5 and not being along a diametrical line so that the hood is asymmetrically offset, and wherein said part spherical member has two generally opposed openings, the first being of a size in the order of a quarter spherical opening in the exposed face and the second opening being in the order of a quarter spherical opening in the recessed surface, said hollow hood being attached to 3 0 the periphery of the first opening whereby the hood may be directed through a range which is up to or at least a complete hemisphere relative to the holding frame and whereby whilst the hood is so directed, the second opening remains fully recessed at all times behind the holding frame and whereby due RAto the opposed quarter spherical openings the reduction to fluid flow therethrough is minimised, whereby said hood can be applied to or adjacent a

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3a source of pollution or contaminants to be removed by a source of reduced pressure through said universal joint and hollow arm.

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9 RECEIVEO :rT 1997 4 Preferably, said mounting means permits said spherical member to rotate through 3600 in one plane and pivot through a range which is up to or at least 900 in all other planes whereby the hood by a combination of the rotation and pivoting movements has a sweep through a range which is up to or at least a complete hemisphere from positions parallel to the holding frame.

Preferably also the arm includes an angle joint for connecting an elongated hollow member at either or both ends, said joint comprising two portions, each portion having an arcuate wall to move in overlapping motion with respect to each other, said arcuate walls being positioned on one side of the angle joint, 1 0 a pair of walls opposite said arcuate walls, and a hinge pin positioned on the centre line of said opposite walls joining the two portions whereby the angle joint pivots with a degree of movement of up to 1800.

Preferably each portion of said angle joint is hollow and comprises five walls, a first wall being an arcuate surface with centre of curvature being the hinge 1 5 pin, a second wall being an extension of one end of the arcuate wall shaped to allow connection to an elongated hollow member, a third wall being opposite said first and second walls and adjacent to said hinge pin which is positioned on said third wall's centreline, and fourth and fifth walls being opposite each other to complete said angle joint, whereby each portion can move in overlapping motion with respect to each other by pivoting with a degree of movement of up to 1800.

BRIEF DESCRIPTION OF THE DRAWINGS.

In order to more fullydescribe the invention reference will now be made to the accompanying drawings in which:- Figures 1 to illustrate examples of typical applications of the invention, Figure 2 is a view partially cut away of the universal joint of the invention, and Figure 2(b) is a cross sectional view thereof, Figures 3 to show examples of the relative positioning of the hood of the universal joint, 3 0 Figure 4 illustrates the control mechanism of the universal joint,

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K T/ 0047 1 RECEIVED 2 1 JUL 1997 Figure 5 shows in and the range of movement of the angle joint, Figure 6 is an exploded view of the angle joint and Figure 6 is a view of the assembled angle joint shown in cross section, Figure 7 is an exploded view of the hood and universal joint, and Figure 8(a) and 8(b) show a comparison of the present invention with the prior art.

DESCRIPTION OF THE PREFERRED EMBODIMENT.

Figure 1 illustrates typical applications of the invention, Figure 1 illustrating the invention as a hanging arm for pollution control. The adjustable arm 1 1 0 having in this example an upper arm 2 and a lower arm 3 connected by a joint for convenience called an angle joint 4. The upper arm 2 is connected to an angle joint 5 and swivel 6 attached to an overhead support and ducting, while the lower end of the arm 3 has attached thereto a universal joint 7 with hood 8.

Figure 1 illustrates a further application for pollution control where the arm is a standing arm, the swivel 6 facing downwardly and attached to a lower support.

Figure 1 is a diagrammatic illustration of the arm showing a further position which can be obtained.

Figure 1 are illustrations of the angle joint 4 and the universal joint 7 with hood 8 being used as duct elements.

AMENDED SHEi IFA/,^ I I~ 6 Reference is now made to Figures 2, 3 and 4 to more fully describe the universal joint 7. The joint comprises a spherical member 9 mounted in a holding frame 10 and supporting ring 11. The spherical member 9 has a pair of pivot pins 12 positioned opposite each other on a diameter of the spherical member 9, each of the pivot pins having head 13 with a slot 14 positioned over the supporting ring 11 so that the pivot pins may slide around the ring whereby the spherical member can be rotated through 3600. A hollow adjusting bolt 15 with head 16 is positioned within the spherical member 9 and passes with sliding clearance over the pivot pin 12, the thread 17 of the hollow adjusting bolt 15 engaging in a corresponding internal thread 18 in an insert 19 in the spherical member 9. The hollow adjusting bolt 15 engages against the head of the pivot pin so that by rotation of the hollow adjusting bolt the pivot pin can be adjusted relative to the supporting ring 11 to vary the frictional resistance there between. Thus while the spherical member can be rotated through 360 degrees around the supporting ring, the spherical member can also pivot through 900 about the pivot pins for selective positioning of the hood 8.

The ring 11 is supported in the holding frame 10 by four adjusting screws accessible from the outside of the holding frame 10 and engaging a captive nut 21, a spring 22 positioned about each screw 20 between the holding frame and the ring. The holding frame 10 has an internal flange 23 on which a seal 24 is positioned, the seal 24 engaging the outer surface of the spherical member in a sealing manner. As the seal 24 is offset from the position of the pivot pins, by adjusting the screw 20, pressure of the seal on the outer surface of the member can be adjusted as desired. Thus the frictional resistance of the seal on the member can be adjusted such that the member will remain in any position required by the position of the hood. In the drawings the holding frame is preferably the end face of a connector 25 which joins the universal joint to the lower arm 3 or other structure.

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?CT/AU 900 0471 RECEIVED 2 6 MAY 1997 7 The hood 8 is joined to the spherical member, the spherical member having generally opposite openings 26 and 27 to allow passage through the spherical member. The hood 8 is positioned on the surface of the spherical member over the opening 27, the hood being positioned asymmetrically offset from the centre line of the spherical member. The hood covers in the order of one quarter of the surface area of the spherical member, the wall 28 being on or adjacent to a diametrical line of the spherical member. The wall 28 can be positioned as in Figure 2(b) being slightly away from a diametrical line of the spherical member and thus being positioned adjacent to that diametrical line.

The opposite wall 29 when extended would form a chord across the spherical member and diverges away from the wall 28 as it extends from the spherical member and is not on a diametrical line. The side walls 30 which can be parallel to each other, extend from the spherical member adjacent the pivot pins to complete the hood. To maximise the pivot angle, the pivot pins are positioned in a plane which is just inside and in close proximity to the plane of the holding frame and the seal 24, as shown in Figure By having the hood asymmetrically offset as described, the range of movement of the hood is increased to cover up to or at least a full hemisphere, compared to that which would be obtained if the hood were symmetrical relative to the spherical member as is the case with existing orbital nozzles. By shaping the two openings 26 and 27 of the spherical member so that each covers approximately one quadrant or quarter sphere, and so that each has approximately rectangular shape, resistance to fluid flow is minimised and the edges of the opening 26 remains just inside the seal 24 when the spherical member is pivoted or rotated to the extremities of its travel.

As noted above each opening in the spherical member covers approximately a quarter of the spherical member, and to illustrate this further reference will now be made to Figure 7 which shows an exploded view of the opening 27 in the ball, that is the throat area, which opens to the hood 8 attached to the spherical member 9. This throat area or opening 27 is large relative to the cross sectional area of the spherical member 9. In one embodiment of the invention the ratio of opening 27 to the cross sectional area of the spherical member 9 is in the order of 1:1.6. This large throat area is achieved by the intersection of the hood on the spherical member which comprises two semicircles across the spherical member, the two semicircles being at right Rangles. These two semicircles meet at a point which is coincident with the RA% seal 24 and is thus slightly offset from the diameter of the ball. If the ball and AMENDED SHEET V- I P-A/AU I I r j 8 hood are fabricated separately, then the ball would have its opening fabricated by cutting a segment out of it, by using two straight cuts resulting in a throat area of approximately a quarter of a sphere.

However it is to be noted that this throat area is greater than the cross sectional area calculated in respect of DE 732070 (referred to in the prior art) which shows a nozzle which is free to move through a full hemisphere by a combination of pivoting through 90" and rotation through 3600. It has been calculated from the drawings in DE 732070 that the ratio of the throat area to the cross sectional area of the ball (or spherical member) is in the order of 1:6.

1 0 Thus the throat area of the present invention to the throat area of DE 732070 is in the order of 1:4, ie the throat area of the present invention is approximately 4 times the throat area of DE 732070.

Referring now to Figures 8(a) and which diagrammatically show the present invention in full lines and DE 732070 in dotted lines to further illustrate 1 5 the invention. The spherical member 9 is mounted in a wall 50 and the opening 27 is formed by two straight cuts 51 and 52 at right angles to each other, these meeting at or in the vicinity of the centre 53 of the spherical member, resulting in the opening 27 being a quarter of the spherical member 9.

However DE 732070 on the other hand has the opening 54, apparently either circular or egg shaped, to which the hood 55 is attached. This results in a small opening producing a restricted throat area with consequential high pressure drop to the passage of air there through which is of no great consequence in a ventilation system. However the invention has a large throat area permitting the invention to be used under reduced pressure to extract pollutants from the adjacent area.

Furthermore the hood has a shape which is non-conical where it joins the spherical member. On one side the hood has a flat surface 28. This flat surface, if extended passes close to the centre of the ball, while on the opposite side the hood has a semicircular surface 29, where it joins the other hemisphere of the spherical member. This surface 29 and the two opposite surfaces 30 combine into a semicircle where they meet the ball. Thus this is possible geometrically, if a sector is cut out of a sphere, then a flat surface can Sbe joined to extend from one side of the sector whilst the remaining o ,AMENDED SHEET

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7~~ PCT/AUg6/0047 1 9 semicircular surface can be joined to extend from the other side of the sector.

Thus it is the combination of the two factors, throat shape and hood shape which results in the combination of two effects, large throat area and the ability to fully pivot through 900 and rotate through 3600.

Thus as shown in Figures 3 and the hood is able to partake of a range of movements, it being realised that the hood can be positioned in any intermediate position or positions as a result of a combination of movements.

In Figure 3 the hood is moved from position A through position B to position C by rotation anticlockwise through 1800 about the axis R-R shown. The hood changes position by 1800 with the face of the hood remaining at 900 to the face of the holding frame. This rotation is achieved by moving the spherical member around the ring with pivot pins sliding on the ring. It will be appreciated that the rotation about axis R-R can be continued past the 180" position through the full 3600 if desired and further past the 3600 to any greater degree so desired.

Figure 3 illustrates the movement of the hood again starting at position A to position D by pivoting the hood about the axis P-P shown, that is about the pivot pins so that the hood changes position by 900 and reaches the extremity of its pivotal motion with the hood face now parallel to the holding frame face.

Figure 3 illustrates a further movement from position A through position E to position F. The hood is first rotated 1350 clockwise about the axis R-R to position E and then pivoted 450 about axis P-P to position F.

Thus it can be seen that the hood can be positioned in a variety of positions by using the combination of rotational and pivotal movements about the respective axes. The adjusting hollow bolts 15 are easily accessible through the hood and the adjusting screws 20 are also easily accessible on the face of the holding frame.

It is noted from the above that the shape of the hood where it meets the spherical member is independent of the shape of the hood at its outlet face, and in the present invention the hood has a square opening. Thus the side of the hood which is semicircular where it intersects the spherical member AMENDED

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Par/AU i& I Ij US~ RECEIVED 2 6 MAY 1997 gradually transforms into three flat surfaces 29, and the two opposite surfaces However surface 28 remains flat throughout its length resulting in a square hood face or opening which has the advantage of extracting pollutants from a flat surface such as a work bench or table, for when one of the surfaces is flush with a workbench or table surface results in the volume of air from which extraction occurs changes from a sphere to a hemisplane, thus significantly increasing the captured distance of the pollutants.

In order to achieve vertical positioning of the hood, the upper and lower arms 2 and 3 are connected by angle joint 4 shown in more detail in Figures 5 and 1 0 6. The angle joint comprises two joined portions 31 and 32 to connect to the respective upper and lower arms 2 and 3. Portion 32 has side walls 34, an upper connecting wall 35 and a lower wall 36, and portion 31 is similarly constructed with side walls 34(a), upper connecting wall 35(a) and lower wall 36(a). The upper connecting wall 35 of portion 32 connects to an arcuate wall 1 5 37 having its centre of curvature the threaded pivot rod 38, while the upper connecting wall 35(a) of portion 31 also has an arcuate wall 37(a) whose centre of curvature is also on threaded pivot rod 38. However the radius of curvature of arcuate wall 37 is less than the radius of curvature of 37(a) sufficient that the arcuate wall 37 will pass within the arcuate wall 37(a). Also the distance between walls 34 is less than the distance between walls 34(a) so that the two joined portions can pivot in overlapping relationship. The arcuate walls are thus raised above the top connecting walls 35 and 35(a) and dimensioned such that when in position 5(a) the arcuate wall 37 does not extend below the wall 35(a) to partially obstruct the passage therein. Figure 5(b) shows the angled joint in an angled position, and preferably a stop, (not shown) is positioned to prevent an excessive angular movement to prevent arcuate wall 37(a) from extending past the edge of the arcuate wall 37.

Preferably a seal 39 is positioned inside the edge of the walls 34(a) and arcuate wall 37(a) to seal on the corresponding arcuate wall 37 and walls 34.

However by constructing the portions 31 and 32 with the desired tolerances, the seal 39 may not be required.

The walls 34 and 34(a) have depending lugs 40 and 41 these being apertured to receive the threaded pivot rod 38, the lugs 40 being positioned inside the lugs 41. A spacer tube 42 is positioned between the lugs 40, and the threaded pivot rod is provided at each end with a friction disc 43 and disc Sspring 44, these being fitted over the shank of a bearing 45. A nut 46 on each AMENDED SHEET

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1 F 11 end of the threaded pivot rod is adjustable to provide the frictional resistance to the relative movement of the upper and lower arms 2 and 3 so that they may be held in the desired position relative to each other. In order to minimise leakage, seals 47 can be positioned on the adjacent edges of the walls 36 and 36(a), the seals pressing against the spacer tube 42. However by constructing the walls with the desired tolerances the seals 47 may not be required. Thus it can be seen the spacer tube protrudes only to a limited extent into the passage through the angle joint, and so there is a minimum of disturbance of and restriction to the fluid flow through the angle joint. By the 1 0 positioning of the hinge on one side of the angle joint on the opposite side to the arcuate walls, there is a virtual unobstructed flow of fluid through the angle joint, and in fact the cross sectional area through the angle joint is greater than the cross sectional area of the upper and lower arm portions 2 and 3. The air thus in passing from one arm portion 2 to the other arm portion 3 has only one change of direction and a minimal restriction to fluid flow.

The angle joint 5 is of similar construction and thus need not be described.

Thus it will be seen that according to this invention there is provided an adjustable arm which is of solid construction. The construction eliminates the use of flexible hoses which can be subjected to abrasion, corrosion, accidental damage and the presence of pollution traps. The interior of the arm is smooth and at the joints there is little restriction to fluid flow and minimum changes of direction thus resulting in very little pressure drop at the bends.

The universal joint has no flexible hose and its hood has a wide range of movement through a complete hemisphere. The angle joint has no flexible hose and only one change of direction. Both joints are self-supporting and can seal against fluid flow.

While the upper and lower arms and connectors are illustrated as being of square or rectangular in cross-section it is to be realised that the arm and angle joints could have a cross section other than square or rectangular. Thus 3 0 the invention is also applicable to circular arms and the overlapping portions instead of being arcuate in one dimension, can be part spherical. Further the invention is also applicable to octagonal, triangular, oval or semicircular arms.

Additionally one or more additional curved portions can be added to the angle joint to create additional overlapping arcuate surfaces thus allowing the angle RAQ 35 joint to rotate from 00 to a full 1800 whilst maintaining air sealing.

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Pcr/AU 9 6 0 0 4 71 12 Devices alternative to the friction disc 43 and disc spring 44 can be positioned on the inside or the outside of the angle joint to control the relative movement of the joint. These include coil springs, gas struts, counter balance weights and pantograph mechanisms.

Whilst the universal joint has a hood which is described in shape as square or rectangular it may be other shapes such as oval. The shape and construction of the spherical member itself may be varied. The manner of adjusting the frictional resistance to movement of the spherical member may be varied, and either one of the described methods may be eliminated if desired.

1 0 Alternatively instead of having the ring 11, springs 22 and screws 20, the desired frictional resistance could be provided by a wide seal with a double profile, or by using two seals one on each side of the centre line of the spherical member by using a solid band surrounding a portion of the spherical member. Whilst the universal joint can pivot through 90' it will be appreciated 1 5 that the hood, the holding frame and the openings in the spherical member can be shaped so that the universal joint can pivot through a range which is up to or at least 900, such as 800 or 1000, and thus the hood can be directed through a range which is either less or greater than a complete hemisphere.

The lower and upper arm 2 and 3 may be constructed in various lengths for example from 0 to 5.0 m with different cross sectional areas. The upper arm 2 and angle joint 4 can be removed if required, with lower arm 3 directly connecting to angle joint 5, to result in an arm with one less degree of freedom. Various other combinations and permutations of upper and lower arms 2 and 3, angle joints 4 and 5 and universal joint 7 can be used to result in various degrees of freedom. For example the universal joint 7 can be used on its own for a ceiling light or the angle joint 4 can be used on its own for a duct element.

One or both of the upper or lower arms may be telescopic to vary the reach of the arm and they may be constructed of any desired material or combination of 3 0 materials, such as metal, plastic, fibre glass.

The universal joint and angle joint can be fabricated, cast, moulded, pressed or otherwise formed from a range of materials including metals, plastics or SAMENDED

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of IPEA/AU ?CT/AU 9 6j 0 1 RECEIVED 2 6 MAY 1997 13 Although various forms of the invention have been described in some detail, it is to be noted that the invention is not to be limited thereto, but is to include variations and modifications falling within the spirit and scope of the invention.

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Claims (16)

1. A dust or fume extractor, said extractor including a hollow hood on a universal joint connection to a hollow arm, said joint including a holding frame, a hollow part spherical member positioned within said frame, said part spherical member being recess mounted in said frame to provide an exposed face of the part spherical member and a recessed surface, said hollow hood attached to said exposed face of the part spherical member asymmetrically offset from the centre of the said exposed face, said hood having two walls 1 0 where it joins the part spherical member, a first of said walls being flat and positioned to extend normal from said exposed face along or adjacent to diametrical line of said part spherical member, a second of said walls being curved and positioned opposite said first wall to extend from said exposed S. 1 face to extend from a chord of said part spherical member, said chord 1 5 diverging from the first wall and not being along a diametrical line so that the .hood is asymmetrically offset, and wherein said part spherical member has two generally opposed openings, the first being of a size in the order of a quarter spherical opening in the exposed face and the second opening being in the order of a quarter spherical opening in the recessed surface, said 2 0 hollow hood being attached to the periphery of the first opening whereby the hood may be directed through a range which is up to or at least a complete hemisphere relative to the holding frame and whereby whilst the hood is so directed, the second opening remains fully recessed at all times behind the holding frame and whereby due to the opposed quarter spherical openings 2 5 the reduction to fluid flow therethrough is minimised, whereby said hood can be applied to or adjacent a source of pollution or contaminants to be removed by a source of reduced pressure through said universal joint and hollow arm.

2. A dust or fume extractor as defined in claim 1 wherein the hood can sweep through 3600 in a plane parallel to the holding frame, and pivot through 3 0 a range of 900 in all other planes.

3. A dust or fume extractor as defined in claim 1 or claim 2, wherein said two walls of the hood where it joins the part spherical member transforms into four walls at the hood face resulting in a square shape. I

4. A dust or fume extractor as defined in any one of claims 1 to 3 wherein the universal joint can be connected to either one or both ends of an elongated hollow member.

5. A dust or fume extractor as defined in claim 1 wherein the holding frame includes a circular ring, diametrically opposed guides on said part spherical member slideable on said circular rings, whereby the part spherical member may rotate relative to said circular ring.

6. A dust or fume extractor as defined in claim 5 wherein said 1 0 diametrically opposed guides each comprise a member pivoted to said part spherical member, a slotted portion engaging said ring whereby said part spherical member is pivoted to said pair of members. .o

7. A dust or fume extractor as defined in claim 6 wherein said pair of members are each a pivot pin extending through the wall of the part spherical 1 5 member, a head on one end of each pivot pin slotted to engage said circular ring, a hollow threaded bolt threaded into said wall of said part spherical member and engaging the head of said pivot pin whereby the gap between the pivot pin and the ring and/or the frictional resistance of the pivot pin on the ring is adjustable to control the movement of the part spherical member relative to the ring.

8. A dust or fume extractor as defined in claim 6 wherein said holding frame includes a circular sealing member sealing on the outer surface of the part spherical member, circumferentially spaced from the circular ring, adjustment means between the holding frame and the circular ring whereby the sealing pressure on the part spherical member can be varied by movement of the sealing member relative to the circular ring.

9. A dust or fume extractor as defined in claim 1 wherein said arm has two portions joined by an angle joint, said angle joint having a pair of co- operating arcuate walls on one side of the arm and a hinge pin joining the two 3 0 portions of the arm on the side of the arm opposite said arcuate walls whereby the fluid passing through the angle joint has only one change of direction and Rhas negligible loss of fluid pressure of fluid passing through it, said angle joint having a range of movement of up to 1800. A dust or fume extractor as defined in claim 9 whereby each portion q 4 999*** 9 9 9 9*9* 99 S* 99 S S 99*9 9 *9 9 a S. 9 9 I~ I nn I liBJ 16 of said angle joint is hollow and comprises five walls a first wall being an arcuate surface with centre of curvature being the hinge pin, a second wall being an extension of one end of the arcuate wall shaped to allow connection to an elongated hollow member, a third wall being opposite said first and second walls and adjacent to said hinge pin which is positioned on said third wall's centreline, and fourth and fifth walls being opposite each other to complete said angle joint, whereby each portion can move in overlapping motion with respect to each other by pivoting with a degree of movement of up to 1800.

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11. A dust or fume extractor as defined in claim 10 whereby the radius of curvature of the said first arcuate wall of one portion is less than that for the other portion, and the dimension between the said fourth and fifth walls of one portion is less than that for the other portion, whereby the two portions can pivot around said hinge pin in overlapping relationship with respect to each other.

12. A dust or fume extractor as defined in claim 10 whereby when pivoted to a maximum extreme, a stop ensures that the said first arcuate wall and fourth and fifth walls of one portion do not extend past the edge of said arcuate wall and fourth and fifth walls of the other portion, and when pivoted to the minimum extreme, the first arcuate wall of one portion does not create an obstruction below the surface of said second connecting wall of the other portion, thereby not creating a restriction to fluid flow.

13. A dust or fume extractor as defined in claim 10 wherein said arcuate walls extend above the adjacent surfaces of said second wall which connect to said elongated hollow members, said hinge pin passing through apertured lugs on the respective joint portions, a spacer on said hinge pin between the lugs on each side of the joint portions.

14. A dust or fume extractor as defined in claim 13, a thread on each end of said hinge pin, an adjustable friction disc, disc spring washer and threaded nut on each end of said hinge pin whereby the angle of said angle joint can be frictionally held in position.

A dust or fume extractor as defined in claim 14 wherein sealing strips C-,are applied to the edges of the outer arcuate portion to seal on the inner -7 $MDg 8-Ej PCT/AU 9 /0 04 7 1 's '317 arcuate portion.

16. A dust or fume extractor as defined in claim 13 wherein sealing strips are positioned on the edge of each of the joint portions adjacent said spacer to seal on said spacer. AMENDED SHEET 'iP7ai'A.U