GB1582841A

GB1582841A - Workbenches

Info

Publication number: GB1582841A
Application number: GB18293/76A
Authority: GB
Original assignee: Inventec Patents Ltd
Current assignee: Inventec Patents Ltd
Priority date: 1976-05-05
Filing date: 1976-05-05
Publication date: 1981-01-14
Also published as: BE854329A; BE854327A; ZA772674B; BE854328A

Description

(54) WORKBENCHES (71) We, INVENTEC PATENTS LIMITED (formerly known as Patentec Limited), a Company registered under the Laws of the Republic of Ireland, of 51-52 Fitzwilliam Square, Dublin 2, Eire, 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 workunits or workbenches. The applicant is the proprietor of the following British Patents.

1.3r7 ()t2 1,267,033 1,267,034 1,267,035 1,405,892 1,405,893 1,405,894 1,405,895 1,405,895 1,422,521 All of these Patents relate to a workbench which has been shown to be an extremely practical adjunct inter alia for professional and amateur carpenters and do-it-yourself craftsmen generally.

Whilst not wishing to detract from the success of previous designs such as those shown in the Patent Specifications referred to above, the inventors have found that, by careful redesign, certain aspects of the bench can be improved and at the same time certain economies made in manufacture.

According to the present invention, a workbench comprises a top structure which includes a pair of substantially horizontal elongate vice beams, at least one of which is movable relative to the other for clamping of a workpiece therebetween, the vice beams having upper surfaces lying in substantially the same plane to form a working surface, and a supporting structure connected to the top structure and including front and rear generally flat frames pivoted at their upper ends by front and rear pivotal connections to the top structure for movement between erected and collapsed positions, the front and rear pivotal connections being disposed adjacent the front and rear of the top structure respectively, the frames, as viewed in side elevation when erected, being downwardly and outwardly splayed and having feet which in the erected position can engage a floor at points forward and rearward respectively of a plan projection of the top structure, the frames being arranged, when folding from the erected position to the collapsed position each to move in the same rotary direction with respect to the top structure with one frame leading the other, trailing, frame during such rotation, the frames being interconnected by rigid links, one at each end of the bench, which are pivoted to the frames by further pivotal connnections of which the pivotal connection to the leading frame is substantially lower on the leading frame than the pivotal connection of the link to the trailing frame such that; during collapsing, the trailing frame approaches the leading frame and, in the collapsed position, at least part of the trailing frame lies adjacent to the leading frame.

According to another aspect of the invention, a workbench comprises a top structure which includes a pair of elongate vice beams, at least one of which is movable relative to the other for clamping of a workpiece therebetween, the vice beams having upper surfaces lying in substantially the same plane to form a working surface, and a collapsible supporting structure which includes a first generally flat frame and a second generally fiat frame, which frames are pivotally connected to the top structure for swinging movement about first and second pivot axes, respectively, between a collapsed position in which the frames and the top structure lie dose together, with the first frame lying on the same side of the second frame as ddes the top structure, and an erected position in which the frames support the top structure above the ground, with the frames diverging from one another in the downward direction, and the supporting structure also including at least one link whose ends are connected to the first and second frames for pivoting relative to the first and second frames about third and fourth pivot axes, respectively, which axes, when the supporting structure is in its erected position, lie at a lower level than either of the first and second pivot axes, with the third pivot axis at a level which is sufficiently below the level of the fourth pivot axis that the sum of the distances between the first and second pivot axes and between the first and third pivot axes is substantially equal to the sum of the distances between the second and fourth pivot axes and between the third and fourth pivot axes, so that, in the collapsed position of the workbench both the first and fourth pivot axes can lie close to the plane joining the second and third pivot axes.

According to a specific construction at least one of the frames includes a pair of legs connected, adjacent their ends remote from the top structure, by a horizontal cross member. The end or ends of the or each link associated with the legs of the frame or frames conveniently lies adjacent one or other of the legs, on the side of that leg closest to the other leg of the pair. In this case, where the second frame includes a pair of legs and a horizontal cross member, the or each link may deviate from the straight line joining the third and fourth pivot axes, at least over the part of its length which lies adjacent the horizontal cross member in the collapsed position of the workbench, the deviation being an upward deviation when seen in the erected position of the frames.

Preferably the supporting structure also includes means for locking the frames in their erected position; this locking means may comprise at least one folding linkage comprising two parts connected by a pivot, the ends of the or each linkage being pivotally connected, respectively, to the second frame and to the top structure, and the axes of the pivotal connections at the ends of the or each linkage conveniently coincide with the first and fourth pivot axes.

Preferably, as the workbench is moved from its collapsed to its erected position, the or each folding linkage moves through a position in which its three pivots are collinear, and afterwards reaches a position in which further relative pivoting of the two parts of the linkage is prevented. The or each folding linkage may be fitted with an overcentre action spring acting to hold the linkage in its erected position.

With the workbench in its erected position, the frames preferably diverge in the downward direction to place their feet outside the worktop plan.

For convenience of manufacture, when the workbench is erected, the first and second frames lie at equal but opposite angles to the vertical. It is possible however as an alternative for the frames to lie at different angles from the vertical, in particular so that the user may easily stand on a horizontal cross member on the frame having the greater inclination either for sawing a workpiece, or for climbing on to the top structure. Also the horizontal cross member can be used for foot-thrust use to stabilise the bench at either height.

The movements of the said one vice beam may be produced by operation of one or both of a pair of clamping devices spaced along the length of the vice beams, which clamping devices are capable of independent operation, whereby the gap between the vice beams may taper along the length of the vice beams, and the said one vice beam being restrained against rocking about axes parallel to its length in response to the reaction force exerted by a workpiece on the said one vice beam. Moreover the top structure may include a pair of elongate supports which extend transversely to the length of the vice beams, one near each end of the vice beams, and below the level of the vice beams, and on which the vice beams are mounted, the first and second frames being pivoted to the elongate supports.

In order to be able to clamp downwardly extending workpieces the vice beams preferably project at their ends beyond the elongate supports for the vice beams; furthermore each of the frames may comprise a pair of legs, each leg being pivoted to the side of one of the elongate supports which is remote from the other of the elongate supports, and, with the workbench erected and seen in plan view with the vice beams fully spaced apart, the legs do not underlie the gap between the vice beams.

Constructions of the type described can be made much more cheaply than those described in the prior patents referred to above. They have the great merits of simplicity, lightness, and ease of erection and folding. Nevertheless, when erected, the top structure, frames and links provide a very rigid five sided boxlike construction with each side of the box forming a rigid diaphragm capable of resisting shear loads.

The invention may be carried into practice in various way, but one specific workbench embodying the invention, and a number of modifications thereof, will now be described by way of example, with reference to the drawings accompanying the -Pm- visional Specification of Application No.

10425/77, of which: Figure 1 is a perspective view of the workbench in a reduced height position, in which the bench may be used as a sawhorse; Figure 2 is a view, similar to Figure 1, but with the workbench in its full height position; Figure 3 is a side elevation of the workbench when collapsed for storage; Figure 4 is a side elevation showing the workbench in the process of being erected; Figure 5 is a side elevation showing the workbench in the position of Figure 1; Figure 6 is a view similar to Figure 5, but showing the workbench in the position of Figure 2, and taken in section on the median plane of the workbench; Figure 7 is a plan view of the workbench in its full height position; Figure 8 is a partial section on the line VIII--VIII in Figure 7;; Figures 9 and 10 are partial sections on the lines IX-IX and X-X in Figure 8; Figure 11 is a perspective view of part of the workbench, taken in the direction of the arrow XI in Figures 5 and 7, with some parts of the workbench shown in chaindotted line; Figure 12 is a perspective view of part of the workbench taken in the direction of the arrow XII in Figures 5 and 7, with some parts of the workbench shown in chaindotted lines; Figure 13 is an underside view of the ton nart of the workbench, with the beams which form the top surface of the workbench positioned parallel to one another; Figure 14 is a view, similar to Figure 13, but with the beams at an angle to one another; Figure 15 is an enlarged view, corresponding to part of Figure 6; Figure 16 is a view, similar to Figure 15, but taken with the workbench partly collapsed;; Figure 17, is an enlarged view, partly in section, looking along the arrow XVII in Figure 6, and showing one lower corner only of the workbench; Figure 18 is a view taken looking along the arrow XVIII in Figure 5, showing only the lower part of the workbench; Figure 19 is an enlarged view, taken looking along the arrow XIX in Figure 5, and showing one lower corner only of the workbench; and Figure 20 is an enlarged view, corresponding to part of Figure 6, illustrating part of the folding action of the workbench.

As can best be seen from Figure 1, the workbench consists of a worktop 10, which is supported on a collapsible supporting structure 12. The worktop 10 consists essentially of two elongate wooden vice beams 14 and 16, which have their upper surfaces in the same plane and which together provide the working surface of the workbench, and two elongate supports 18, on which the vice beams 14 and 16 are mounted. The supports 18 extend transversely to the length of the vice beams 14 and 16, one near each end of the vice beams. The vice beam 14 is rigidly connected to the supports 18, but the vice beam 16 can be shifted along the supports 18, towards and away from the vice beam 14, by manipulation of two crank handles 20, so that a workpiece can be clamped between the vice beams 14 and 16.

The collapsible supporting structure 12 consists of a front frame 22 and a rear frame 24, which are connected by pivots 26 and 28, respectively, to the elongate supports 18. When the bench is in use, the frames 22 and 24 are in the positions shown in Figure 1, in which they are splayed apart so that their lower, ground-engaging ends are well spaced, so that the bench is sufficiently stable. The pivots 26 and 28 allow the frames 22 and 24 to be swung, relative to the worktop 10, from their erected position, as shown in Figure 1, to a collapsed position, shown in Figure 3, in which both frames lie parallel to the working surface of the worktop. At each side of the bench, a linkage 30 connnects the two frames, so that movement of one frame from its erected position to its collapsed position, or vice versa, results in a corresponding movement of the other frame.The linkages 30 are so arranged that they lock into position when the bench is erected, so that the bench then becomes a rigid structure.

Each of the frame 22 and 24 includes, at its bottom end, two pivoted extension legs 32. These legs can be moved between a storage position, shown in Figure 1, in which they play no part in supporting the bench, and an operative position, shown in Figure 2, in which they increase the effective height of the supporting structure 12.

With the extension legs 32 in their storage position, the working surface of the bench is about 23" from the ground; this is a convenient height if the bench is to be used as a sawhorse. With the legs 32 in their operative position, the working surface of the bench is about 32" from the ground; this is a convenient height for operations such as planing.

It will be seen from Figure 2 that the extension legs 32 are splayed, as seen in front or rear elevation, so that their use increases the lateral spacing between the points at which the supporting structure engages the ground. The front-to-back spaced ing of these points is also increased by use of the extension legs 32, because these legs lie in the same plane as theframes 22 and 24, which are themselves splayed. Thus, a change from the lower, sawhorse, heist to the greater height is automatically accom panied .by an increase in the spacings be tween the ground contact points, so that the stability of the bench is maintained; this is illustrated by Figures 5, 6 and 7.

The parts of the bench will now be described in greater detail.

Each of the vice beams 14 and 16 consists of a length of plywood, of rectangular crosssection, and is formed with a nunber of vertical bores 44, which can receive clamp ing abutments, in the manner disclosed in British Patent No. 1,422,521. As shown in Figure 7 each vice beam is also formed with a vertical counterbored hole 46 near each end, which receives a fixing bolt 48 and 50.

Each of the elongate supports 18 is in the form of a sheet steel pressing, which is L-shaped in section. As can be seen front Figures 8, 9 and 10, the longer leg of the L points downwards, while the shorter leg points horizontally inwards, towards the other of the elongate supports 18. As mentioned above, the vice beam 14 (hereafter referred to as the front or fixed vice beam) is rigidly connnected to the supports 18, but this connnection is not direct; two spacer blocks 34, one at each end of the vice beam 14, separate the vice beam from the supports 18. Each spacer block is an aluminium alloy die-casting, and its shape can be seen most clearly in Figures 10 and 11.The main part of the spacer block is roughly I-shaped in plan, with the height of the I extending parallel to the length of the support 18, although it will be noticed that the four flanges are not all of the same width.

On the outboard side of the stem of the I, the spacer block has three vertically-extending bosses 36, 38 and 40. Of these bosses, the central boss 38 has a vertically-extending bore 42, which receives the fixing bolt 48; the head of the bolt, together with a washer, is received in the counterbore in the vice beam 14, while the threaded endof the bolt 48 passes through a hole in the horizontal leg of the support 18 and into .a nut brazed on the underside of this leg, all as shown in Figure 10.The other two bosses 36 and 40 are continued upwards, above the general level of the top surface' of the spacer block 34, which abuts against the underside of the vice beam 14; the continuations of these bosses form two locating spigots 52, (Figure 11), which are received in blind bores in the underside of the vice beam, so that the spacer block cannot move angularly relative to the vice beam 14 about the fixing bolt 48.

Each spacer block 34 his an integral continuation, in the form of a web 54 which extends generally horizontally, in the inboard direction (that is to say, 'towards' the re'm'ote end of the vice beam 14) from the lower edge of the spacer block. This web 54 is cranked downwardly where it passes over the inboard edge of the support 18, and the resulting step 56 (see Figure 10) in the underside of the web abuts against this inboard edge, so that angular movement of the spacer block relative to the elongate support about the fixing bolt 48 is prevented. Thus, it will be seen that the vice beam 14, the spacer blocks 34, and the elongate supports 18 form a rigid assembly, even though only a single fixing bolt is used at each end.

The flanges 59 and 61 at the front end of the spacer block 34 are extended downwards beyond the under surface of the main part of the spacer block, as can be seen in Figure 8, and it will also be seen that the inboard flange 61 extends considerably further inboard than the main part of the spacer block 34. The lowest part of this extended flange 61, as shown at 62 is provided with a bore 58, in which is journalled a vice screw 60, which can be operated by one of the handles 20. The flange 62 is braced to withstand forces applied to it by the vice screw 60 by means of the web 54, which merges into the rear surface of the flange 62. In addition, a further integral bracing web '64 extends vertically'downwards from the inboard edge of the web 54, and merges into the flange 62 at its inboard vertical edge.The shape of these flanges can best be seen in Figure 11.

Like the vice beam 14, the vice beam 16 (hereafter referred to as' the '-rear or moving vice beam) is separated from the elongate supports 18 by a pair of spacer blocks 66;.

these spacer blocks can silde along the supports 18, but are rigidly connected to the vice beam 16. The fixing bolts 50 hold the vice beam 16 to the spacer blocks 66; each of these fixing bolts also serves to attach a vice nut 68 to the underside of the associated spacer block 66. The vice screws 60 are threaded into the' vice nuts 68, so that when a workpiece is clamped between the vice beams 14 and 16, by rotation of the handles 20, the clamping forces are carried by the following components; the vice beam 16, bolts 50, the spaces blocks 66, and the vice nuts 68, the vice screws 60, the spacer blocks 34, the bolts 48, and the vice beam 14. It will be noted that the elongate supports 18 do -not carry the main clamping loads.

As shown 'in' Figures 8, 9, and 12 each of the spacer blocks 66 is a box-like aluminium 'alloy die-casting which includes three vertically-extending bosses 70, 72 and 74, of which the central boss 72 has a vertically-extending bore 76, within which the fixing'bolt 50 is received. The bosses are interconnected by a vertical web 73, and the end bosses 70 and 74, liké the bosses 36 and 40 of the front spacer blocks 34, are continued upwards to form locating spigots 78 which are received in blind bores 79 in the rear vice beam 16, so that the rear vice beam and the spacer blocks 66 cannot move relative to one another.

The underside of each spacer block 66 is formed with a vertical step 80 (see Figure 9), which engages against the inboard edge 81 (see Figure 12) of the horizontal-leg of the associated elongate support 18, so that lateral movements of the rear vice beam are restricted by one or other of the supports 18. In this embodiment as shown in Figures 12 and 13, the two vertical steps 80 are formed as arcs of the same circle, with its centre at the middle of the vice beam 16.

The diameter of this circle is almost equal to the spacing between the edges against which the steps engage, so that the rear vice beam has only slight lateral freedom, whether it is lying parallel to or at an angle to the front vice beam 14. The guiding action of the steps 80 is best illustrated in Figures 9, 12 and 13.

Any downward forces on the rear vice beam 16 are simply transmitted to the supports 18 by the engagement of the under surfaces of the spacer block 66 with the top surfaces of the supports 18, on which they slide.

Each of the vice nuts 68 is made in two parts, both of which are aluminium alloy die-castings. The two parts have mating surfaces which lie in a horizontal plane through the axes of the vice screws 60 and are secured together by two screws 82 (see Figure 6). The lower part (shown at 84) of the nut is a simple semi-cylindrical shell, with internal threads, whereas the upper part (shown at 86) of the nut has a generally channel-shaped extension 88 which lies to the rear of the main part of the nut. The two legs of this channel (which are present primarily to provide rigidity) point downwards, so that the top surface of the extension 88 is flat. A bore 90 extends vertically through the extension 88, and receives the fixing bolt 50.The bore 90 open at its bottom end into a hexagonal recess formed in the inner surface of the channel; this recess receives the head of the fixing bolt 50, which is also hexagonal, so that rotation of the bolt relative to the nut 68 is prevented by the engagement of the bolt head in the recess. The bolt extends vertically up through the nut 68,the spacer block 66 and the vice beam 16, and emerges in a counterbore on the top of the vice beam 16, where it is fitted with ,a washer and a stiffnut. The stiffnut is tightened sufficiently to hold the parts together firmly, without play, but not so much that it prevents the vice nut 68 from pivoting relative to the spacer block 66; this pivoting movement is necessary for reasons which will become apparent.A fibre washer 92 (see Figure 9) is interposed between the spacer block 66 and the vice nut 68, to reduce the friction between these components when pivoting occurs.

As well as providing one of the surfaces against which the fibre washer 92 bears the flat top of the extension 88 of the vice nut 68 acts to restrict upward movements of the rear vice beam 16, becaue part of this surface will engage the under surface of the horizontal leg of the support 18. In fact, to ensure that an adequate area of engagement occurs between the nut 68 and the support 18, the top of the extension 88 is slightly widened in the area of the bore 90, so that the top surface of the extension is approximately coffin-shaped, as can be seen in dotted lines in Figures 12 and 13.

As mentioned above, each of the vice screws 60 is journalled in the bore 58 in one of the front spacer blocks 34. Movement of the vice screw 60 forward out of the bore 58 is prevented by a rollpin 94 which passes through a cross bore in the vice screw, and which bears, through a steel washer 96, against the rear of the flange 62.

Movement of the vice screw in the rearward direction is prevented by the crank handle 20, which is secured to the vice screw by a rollpin (not shown), and which bears against the front surface of the flange 62 through a cylindrical plastics spacer 63.

The parts are so dimensioned that sufficient clearances are present to allow the axis of the screw 60 to rock slightly; the reason for this will become apparent shortly.

When a workpiece is to be clamped, it is placed between the vice beams 14 and 16, and the handles 20 are rotated to move the rear vice beam towards the front vice beam.

Since in most cases the two handles will not be rotated in exact synchronism, and in many cases only one handle at a time will be rotated, -it is necessary for the vice beam 16 to be able to adopt a position at an angle to the fixed vice beam 14. Figures 12 and 13 illustrate the vice beams 14 and 16 in parallel and angled relationships, respectively. As explained above, the steps 80 are of a shape which allows this angular movement, without affecting the amount of lateral play allowed to the rear vice beam 16. However, when the vice beam 16 moves to an angled position, each of the fixing bolts 50 moves slightly further away, in the lateral direction, from the adjacent support 18.

This means that the vice nuts 68 also move slightly further away from the supports 18, so that the vice screws 60 must adopt a slightly angled position. As explained above, this movement is possible because of the clearances which are built into the construction. The vice nuts 68 also pivot relative to the rear vice beam 16, about the fixing bolts 50; as explained above, the bolts 50 are not tightened sufficiently to obstruct this movement.

As well as allowing the crank handles 20 to be operated independently, the ability to position the vice beams at an angle to one another means that tapered workpieces can be clamped.

Although, as explained above, the main clamping forces which draw the vice beams 14 and 16 together are borne by the vice screws 60 and not by the supports 18, the supports 18 are responsible for carrying the tilting moment which results from the vertical spacing between the vice screws 60 and the clamping surfaces of the vice beams.

That part of the moment which is borne by each support 18 is transferred to that support in the form of a couple consisting of a downward force acting on the support 18 from the rear end of the associated spacer block 66, and an upward force acting on the support from the most forward part of the flat top surface of the associated vice nut 68.

To prevent the rear vice beam 16 from being moved so far to the rear by manipulation of the handles 20 that the vice screws 60 become disengaged from the vice nuts 68, each of the supports 18 has a turned-up tab 98 at its rear end; the spacer blocks 66 abut against these tabs when the free rear ends of the vice screws 60 are about level with the rear ends of the vice nuts, so that there is still full engagement of the threads.

Each of the front and rear frames 22 and 24 consists essentially of two legs 100 or 102 respectively, joined at their lower ends by a step bar 104. Each leg consists of a length of square steel tubing, fitted at its top and bottom ends with plastics plugs 106 and 108, respectively. The bottom plugs 108 have angled under surfaces, so that they form feet which rest squarely on the ground when the bench is in use at sawhorse height.

The two frames lie at equal engles to the vertical when the bench is erected, so that there need be no difference between the bottom plugs 108 used on the front and rear frames.

The upper end of each of the front legs 100 is pivoted to the outside of the vertical leg of the adjacent elongate support 18 by a pivot pin 110, which passes through holes in the two lateral walls of the leg 100 and in the leg of the support 18, with a washer between the leg 100 and the support 18.

Although many forms of pivot pin could be used, in this specific example the pin has a plain round head and a plain cylindrical shank, and, after being passed through the holes in the components, is retained in place by a spring dip of the type known as a speednut, pushed on to the plain end of the shank. This type of pivot pin is used for most of the other pivotal connections in the supporting structure 12; only those connections which- are of different construction will be specifically described hereafter.

The upper end of the rear legs 102 is connected by a pivot pin 112 to a downwardly-projecting ear 114, which is as an integral part of the vertical leg of the adjacent elongate support 18. A~n, a washer is used between the leg 102 and the ear 114. It will be observed that the pivot pin 110 is at a higher level than the pivot pin 112. The difference in level between the pivot points of the front and rear legs means that, when the bench is collapsed by anti-clockwise rotation of the legs in Figure 5, the front frame 22 lies closer to the plane of the working surface of the vice beams than does the rear frame 24. This is necessary because the rear legs 102, like the front legs 100, lie on the outboard sides of the elongate support 18, and therefore would otherwise be prevented by the front legs from folding to a position exactly parallel to the working surface.

The linkage 30 which connect the two frames 22 and 24 each consist of a lower rigid strut 116 and an upper folding strut 118. The rigid struts 116 are responsible for synchronising the movement of the two frames between their erected and collapsed positions, while the folding struts 118 lock into position when the bench has been erected.

Each rigid strut 116 is a sheet steel pressing of channel-shaped cross-section; the legs of the channel face inboard, towards the opposite end of the workbench. The front and rear ends of each strut 116 are connected by pivot pins 120 and 122, respectively, to the front and rear legs 100 and 102 at that side of the workbench. Washers are fitted between the struct 116 and the legs 100 and 102. As can be clearly seen from Figure 5, the front pivot pin 120 is at a considerably lower level than the rear pivot pin 122 when the bench is in its erected position. The reason for this can be seen from Figure 3, which shows the bench in the collapsed position. In the collapsed position, the front legs 100 have swung forward relative to the worktop 10, so that the pivot pins 110 and 122 lie very close to the line joining the pivot pins 112 and 120. The su.m of the distance along the front leg 100 between the pivot pins 110 and 120 and the distance along the support 18 between the pivot pins 110 and 112 must therefore be almost exactly equal to the sum of the distance along the rear leg 102 between the pivot pins 112 and 122 and the length of the straight line between the pivot pins 120 and 122. The length of this line is greater than the length of the support 18, because of the splay of the legs 100 and 102, and this dictates the greater distance between the pins 110. and 120, as compared with the distance between the pins 112 and 122.

EIowever, if the two sums mentioned above were exactly equal, the quadrilateral formed by the pivot pins 110, 112, 120 and 122 would be exactly symmetrical about the line joining the pins 112 and 120, and the front and rear legs would not be lying parallel to one another. For this reason, the first sum mentioned above is made very slightly greater than the second mentioned sum, by an amount which upsets the symmetry of the quadrilateral sufficiently to bring the front and rear legs into. exact parallelism with one another in the collapsed position of the workbench.

It will be seen from Figures 5 and 6 that the rigid struts 116 have a slight bend 117 at the middle of their length. The reason for this bend can be seen from Figure 3; if the strut were made exactly straight, it would foul the forward (inside) face of the step bar 104 of the rear frame 24. It will also be seen from Figure 8 that the vertical leg of each elongate support 18 has the front part of its bottom edge cut away at a shallow angle, as shown at 124, to provide clearance for the struts 116.

Each of the upper, folding struts 118 consists of an upper portion 126 and a lower portion 128, which are pivoted together, as shown at 130, at approximately the mid-point of the strut. The upper end of the upper portion 126 is pivoted on the pivot pin 110, with a washer between itself and the support 18, while the lower end of the lower portion 128 is pivoted on the pivot pin 122, with a washer between itself and the strut 116; thus, when it is straight, the strut 118 forms a diagonal of the quad rilateral having the pivot pins 110, 112, 120 and 122 at its corners, and thereby braces the supporting structure 12.

Each portion of the struts 118 consists of a sheet steel pressing of L-shaped cross section, arranged with the longer leg of the L pointing vertically downwards and the shorter leg pointing horizontally in board, -towards the opposite end of the bench. The lower portion 128 of the strut lies outboard of the upper portion where they overlap in the region of the pivotal connection 130. The horizontal leg of the upper portion 126 terminates at its lower end alongside the pivot connection 130,, while its vertical leg continues only a short distance past the pivotal connection 130.

However, both legs of the lower portion 128 region extend past the pivotal connection 130 by about 1L inches; as can be seen from Figure 15, this means that the horizontal leg of the lower portion 128 contacts the upper surface of the horizontal leg of the upper portion 126- when the steel sirs it in its straight position, so that the portions of the strut can pivot relative to one another about the pivotal connection 130 in. the downwards direction only.The. pivotal connection 130 is slightly below the line joining the pivot pins 110 and 122 when the strut 118 is in its straight position, so that any tendency of the strut to fold as a result of compressive loading acts in the direction in which folding is prevented by the contact between the horizontal legs of the two portions of the strut.

The struts 118 are folded upwards, with the two portions of each strut swinging downwards relative to one another about the pivots 130, whn it is desired to collapse the workbench for storage. Figure 4 shows the workbench in course of being collapsed in this manner. The lengths of the two portions of each strut are so selected that, in the collapsed position, they lie within the outline of the elongate support 18 and the rear frame 24, as seen in side elevation; this can clearly be seen in Figure 3.

To help to lock the folding struts 118 into their straight position when the bench is erected, and to maintain them in this position, each strut has an over-centre spring arrangement shown clearly in Figures 15 and 16 adjacent the pivotal connection 130.

This arrangement includes a helical tension spring 132, which is connected at its ends to pins 134 and 136 welded to the inner vertical surfaces of the upper and lower portions of the strut 118. As can be seen from Figure 15, in the straight position of the strut, the line of action of the spring 132 lies above the axis of the pivotal connection 130, and so the spring force, like any compressive forces on the strut, tends to lock the strut in its straight position.

Figure 16 shows how, if the bench is collapsed, the folding of the strut 118 results, after a certain amount of folding, in the line of action of the spring 132 lying below the axis of the pivotal connection 130, so that the spring 132 now tends to move the strut 118 to its-fully folded position and holds the bench collapsed.

The pivotal connnections 130 are of different construction from the other pivot pins such as 110. Each of the connnections 130 consists of a hexagon headed bolt 138, which is positioned with its head on the outboard side of the strut 118, and is fitted on the inboard side with a nut 140. The nut 140 is adjusted to allow the strut to fold easily, but without excessive play in the connection 130, and the end of the shank of the bolt 138 is then peened over to lock the nut 140 in position. A washer is used between the two portions of the strut.

Both the head of the bolt 138 and the nut 140 are relatively thin, that is to say, about 3/32 inch. This allows the springs 132 to pass across the axis of the connection 130 as the strut 188 folds, and also allows the connection 130 to lie beside the rear leg 102 when the bench is collapsed, as illustrated in Figure 3.

The rigid strut 116 lies on the inboard side of the legs 100 and 102, while the folding strut 118 lies on the inboard side of the rigid strut 116 and of the elongate support 18. This means that the only parts of the collapsible supporting structure 12 which are further outboard than the elongate supports 18 are the legs 100 and 102. As can be seen from Figure 7, the legs do not lie vertically below the clamping gap between the vice beams 14 and 16. Thus, if it is desired to clamp a long workpiece in a vertical position, with its lower end extending down to ground level, at one end of the vice beams 14 and 16, the extent to which the workpiece can be inserted into the gap between the vice beams is limited not by the legs 100 and 102, but by the supports 18 and the struts 116 and 118.The supports 18 are therefore somewhat spaced laterally from the ends of the vice beams but, because the legs are outboard of the supports 18, the lateral spacing of the feet 108 is almost equal to the length of the vice beams 14 and 16, so that the bench has good stability.

Most of the inboard-pointing legs of the struts 116 and 118 terminates beside the appropriate pivot pin 110, 120 or 122, but the upper leg of the channel-section rigid strut 116 terminates about 1 inch short of the pivot pin 122 at its upper end. This is to allow the folding strut 118 to lie flat against the inboard side of the rigid strut 116, without being obstructed by the legs of the rigid strut.

Each of the step bars 104 consists essentially of a sheet steel pressing, which over the middle part of its length has an asymmetrical channel cross-section, as can be seen in Figure 6. The limbs of the channel extend obliquely downwards at the same angle as the legs 100 or 102 to which the step bar is attached, with the inboard limb of the channel being much shallower than the outboard limb. The top surface of the step bar 104 extends horizontally, providing a surface on which the user of the bench can rest a foot to steady the bench or step on bodily if wishing to use the bench top at sawhorse height while the extension legs 32 are lowered.

At each end of the step bar 104, a lengthways continuation of the longer, outboard limb 105 of the channel section is folded to provide an end portion 142 which closes the end of the channel, and an inboard portion 144 which overlaps the inboard limb 107 of the channel, and in effect provides a downward extension of the inboard limb 107 of the channel to the same depth as the outboard limb 105, over the end part of the length of the step bar 104. The inboard folded portion 144 is welded to the inboard limb of the channel along its top and inboard edges. The step bar 104 is secured between the legs of the front or rear frame 22 or 24 by two bolts 146 at each end, which pass through holes in the legs and in the end portion 142 of the step bar into nuts (not shown) which are welded to the inside surface of the end portion 142.

Each of the extension legs 32 consists basically of a length of rectangular steel tubing. The upper end (as seen with the extension leg 32 in its extended position) is received between the inboard folded portion 144 of the step bar 104 and the outboard limbs 105 of the step bar 104, with the wider sides of the rectangular section facing these portions of the step bar. A pivot pin 148 passes through these portions of the step bar and through the leg 32, so that the leg 32 can swing between its retracted position of Figure 18 in which it extends approximately horizontally, within the cross-section of the step bar 104, and its extended position of Figure 17. To ensure that the leg 32 does not rub against parts of the step bar 104 as it is swung about the pivot 148, a washer is positioned on each side of the leg 32, between the leg and the adjacent part of the step bar.

As well as the folded portions 142 and 144, the step bar has at each end a further folded-in portion 152 (see Figure 17) which extends from the bottom edge of the end portion 142, and is welded along both front and rear edges to the rest of the step bar.

The folded-in portion 152 extends first horizontally inboard at 153 from the end of the step bar, and then, except for the extreme outboard part of its width at 154, adjacent the outboard limb 105 of the channel section of the step bar, extends obliquely upwards at an angle at 157 to match the inclination of the extension leg 32 when in its extended position. The oblique part 157 of the folded-in portion 152 therefore provides an abutment which limits outwards pivoting of the extension leg 32, and, together with the pivot pin 148, resists the bending loads which act in the plane of the front or rear frame 22 or 24 when the extension legs are in use.

As mentioned above, the extreme outboard part 154 of the width of the folded-in portion does not extend obliquely to match the angle of the extension leg; instead, it extends horizontally, so that it lies along the side of the extension leg 32 which is adjacent the longer, outboard limb 105, of the step bar 104, when the leg is in its extended position. The position of.the shear cut which separates this part of the foldedin portion 152 from the oblique portion 157 is so chosen that it coincides with the plane of the adjacent side of the extension leg.

Thus, although the leg 32 does not rub against the step bar through most of its pivoting movement, it engages the part 154 over the final stage of its movement to its extended position, so that the bending moments which tend to bend the leg outwards from the plane of the frame 22 or 24 when the extender legs are in use are resisted not only by the pivot pin 148, but also by the part 154. This arrangement means that the deflection of the extension legs 32 is kept to a minimum.

Each of the legs 32 is provided with an overcentre spring arrangement, to ensure that it remains firmly in either its retracted or its extended position. This arrangement consists of a helical tension spring 156, which is attached at one end to a pin 158, welded to the inboard folded portion 144 of the step bar, and at the other end to a pin 160 which is welded to the inboard side of the leg 32. With the leg in its extende position, the line of action of the spring 156 lies outward of the axis of the pivot pin 148, so that the spring force biases the leg outwards, while when the leg is moved to its retracted position, the line of action of the spring will, after a certain amount of movement, move across to the other side of the pivot axis, so that the spring force now tends to keep the leg in its retracted position.

As shown in Figure 18, both the extension legs attached to one step bar can be accommodated within the cross-section of the step bar, even though their ends will overlap.

Because the arrangement is symmetrical, it does not matter which leg is folded first.

Although both legs, when folded, are hidden behind the deep outboard limb 105 of the channel section of the step bar, the lesser depth of the inboard limb 107 of the channel means that the extension legs are nonetheless accessible, for unfolding and also means that there is nothing for the spring pins 160 to foul when the extension legs are retracted.

To facilitate the manual movement of the extension legs 32 from their retracted positions to their extended position, each of the spring pins 160 is continued about d inch beyond the point at which the spring 156 is attached as shown in Figure 18 to provide a convenient finger grip by which the legs 32 can be moved.

The ground-engaging end of each extension leg 32 is- cut obliquely, and is fitted with a plastics plug 162, which acts as a foot when the extension leg is in use. The oblique cut of the end of the leg extends parallel to the ground surface when the extension legs are in use) along the wider, front and rear surfaces of the leg, but along the other two narrower surfaces of the leg, the cut extends at right angles to the length of the leg. In this way, the legs 32 before the attachment of the spring pin 160) are entirely symmetrical, so that there is no need to manufacture left-handed and righthanded legs separately.

The plastics plugs 162 are also symmetrical. As shown in Figure 6 each plug has two plane surfaces 164 on its underside, which surfaces meet in an arris 166 lying in the plane of symmetry of the plug. As can be seen in Figure 6, one of the surfaces 164 rest squarely on the ground when the extension legs 32 are in use.

Other components of the bench which are symmetrical include the rear spacer blocks 66, and the vice nuts 68.

It is possible that, when the workbench is folded from its erected position to its collapsed position, the front legs 100 will strike the crank handles 20, if these have been left in an unsuitable position. To prevent this contact from causing damage, each crank handle is fitted on its rear surface with a plastics cone 168 (see Figure 20) which points towards the rear of the bench.

This cone is so arranged that, as the bench is collapsed, the cone is the first part of the handle 20 to be contacted by the leg 100 if the handle 20 has been left in an unsuitable position. Depending on whether the leg 100 strikes the cone 168 inboard or outboard of its apex, the handle 20 will be moved smoothly outboard or inboard as the bench is collapsed, so that it does not foul the leg 100.

If the handle 20 happens to be moved inboard by the engagement between the cone 168 and the leg 100, it is left in a position in which it can foul the rigid strut 116 in the collapsed position, in fact, it would be possible for the handle to be trapped between the leg 100 and the strut 116. For this reason, a conical plastics stud 170 (see Figure 20) is snapped into a hole in the inboard lateral surface of each front leg 100, in such a position that it can engage the grip portion 21, of the crank handle 20, if this is in a position to be trapped between the strut 116 and the leg 100, and will move it further inboard, so that although contact will occur between the strut 116 and the handle 20, this contact will simply move the grip portion of the handle further inboard. Figure 19 shows the path followed by the stud 170 when the bench is collapsed.

It should be noted that, when the bench is collapsed, it is not essential for the extension legs 32 first to be moved to their folded position. Thus, the bench can be stored either with its extension legs extended, if sufficient storage space is available, or with its extension legs folded if it is important that the bench should take up as little storage space as possible.

Certain advantages result from arranging the workbench in such a way that, when it is collapsed, the crank handles 20 are at the lower edge of the worktop 10. For example, the crank handles do not increase the overall size of the collapsed workbench, because they cannot project outside the general outline of the bench. Also the workbench is convenient to carry in its collapsed condition, with the top surfaces of the vice beams 14 and 16 resting against the body of the person carrying the workbench; when put down and erected from this position, the crank handles 20 are on the side of the erected workbench from which the bench was previously being carried, so that the user does not have to walk around the workbench.

Obviously, in the case of a similar workbench in which the crank handles are at the top of the worktop when the bench is collapsed, the bench could be carried from the side oppdsite to that mentioned above, so that it would not be necessary to walk around the bench, but it would then be found that, if the part of the bench which is closest to the ground in the collapsed position is rested on the ground while the bench is erected, the rest of the supporting structure of the workbench will swing towords the user as the bench is erected, possibly bruising his legs. The preferred arrangement avoids this occurrence by removing any reason for carrying the workbench from this side.

Although the bench is very compact when in its folded position, it is possible to reduce still further the space which it occupies prior to sale to the user by offering it for sale in a 'knock-down' form. The bench can conveniently be sold as five major subassemblies, namely, a worktop sub-assembly two leg and brace sub-assemblies, and two step bar sub-assemblies. The worktop subassembly comprises the two vice bars 14 and 16, the four spacer blocks 34 and 66, the two vice screws 60, and the two yice nuts 68. Each leg and brace sub-assembly comprises one of each of the following components: an elongate support 18, a front leg 100, a rear leg 102, a rigid strut 116, and a folding strut 118. Finally, each step bar sub-assembly comprises a step bar 104, fitted with two extension legs 32.

To assemble the 'knocked-down' workbench, the user has to engage the elongate supports 18 with the steps 56 and 80 of the spacer blocks 34 and 66; the bolts 48 are then inserted and tightened, to hold the worktop and leg and brace sub-assemblies together. The step bar sub-assemblies are then fitted between the legs 100 or 102, and secured by means of the bolts 146. The bench is then completely assembled.

As an alternative to the use of the plastics studs 170 to move the grip portions of the crank handles 20 inboard when the bench is collapsed, the grip portions of the handles could simply be made of larger diameter, so that direct contact with the legs 100 moves the handles sufficiently far inboard that the subsequent engagement be tween the handles 20 and the struts 116 movs the handles 20 inboard rather than outboard.

A further possible alternative way of preventing the crank handles from being damaged by the legs 100 when the bench is collapsed is to construct the crank handles so that they can pivot relative to their vice screws to a folded position in which the grip portion of the handles points inwards, towards the vice beams 14 and 16, rather than outwards away from the vice beams, Thus, if the legs 100 should foul the crank handles, the handles are simply pivoted towards their folded position. It is also pos- sible for the handles to be folded manually before the bench is collapsed.

Detents may be provided to hold the handles in their working position, and possibly also in their folded position.

On occasion, it may be desired to clamp workpieces of circular cross-section between the vice beams 14 and 16, with the axis of the workpiece generally parallel to the length of the vice beams. Such clamping is facilitated if V-grooves are provided to locate the workpiece. These V-grooves may, for example, be formed wholly in the spacer blocks 34 and 66, or alternatively partly in the spacer blocks and partly in the vice beams, in the form of a chamfer on each component. It is only necessary to provide a V-groove on one of the vice beam and spacer block assemblies to make it possible to clamp circular workpieces securely, but V-grooves can be provided on both these assemblies without introducing any disadvantages.

Many other variations may be made in the design of the workbench without departing from its basic design. For example, the front and rear frames 22 and 24 need not lie at the same angle to the vertical when the bench is erected. The elongate supports 18 might be of some cross-section other than L-shape; for example, they might be of channel cross-section. The pivots at the ends of the folding struts 118 do not have to coincide with the pivots connecting the frame 22 to the worktop 10 and connecting the rigid struts 116 to the frame 24; for example, it is possible for the top end of each folding strut 118 to be connected to a pivot positioned about halfway along the elongate support 18. The curved steps 80 which guide the moving vice beam 16 do not have to be parts of the same circle; so long as they are involutes of the same curve, the vice beam 16 will be adequately guided.

Reference is made to Application Nos.

18687/77 Serial No. 1,582,867) and 18686/77 (Serial No. 1,582,866) which contain the same disclosure but claim different features.

WHAT WE CLAIM IS:- 1. A workbench comprising a top structure which includes a pair df substantially horizontal elongate vice beams, at least one of which is movable relative to the other for clamping of a workpiece therebetween, the vice beams having upper surfaces lying in substantially the same plane to form a working surface, and a supporting structure connected to the top structure and including front and rear generally flat frames pivoted at their upper ends by front and rear pivotal connections to the top structure for movement between erected and collapsed positions, the front and rear pivotal connections being disposed adjacent the front and rear of the top structure respectively. the frames, as viewed in side elevation when erected, being downwardly and outwardly splayed and having feet which in the erected position can engage a floor at points forward and rearward respectively of a plan projection of the top structure, the frames being arranged, when folding from the erected position to the collapsed position each to move in the same rotary direction with respect to the top structure with one frame leading the other, trailing, frame during such rotation, the frames being interconnected by rigid links, one at each end of the bench, which are pivoted to the frames by further pivotal connnections of which the pivotal connection to the leading frame is substantially lower on the leading frame than the pivotal connection of the link to the trailing frame such that, during collapsing, the trailing frame approaches the leading frame and, in the collapsed position, at least part of the trailing frame lies adjacent to the leading frame.

2. A workbench as claimed in Claim 1 in which the supporting structure is so arranged that, when in the collapsed position, the trailing frame lies substantially parallel to the leading frame.

3. A workbench as claimed in Claim 2 in which, when in the collapsed position, the trailing and leading frames lie substantially parallel to the working surface.

4. A workbench as claimed in Claim 1 or Claim 2 or Claim 3 in which at least one of the frames includes a pair of legs which are connected adjacent their lower ends by a horizontal foot-thrusting cross member.

5. A workbench as claimed in any of the preceding Claims in which the supporting structure includes at least one folding linkage comprising two parts connected by a pivot, the ends of the or each folding linkage being pivotally connected to the trailing frame and to the top structure, respectively.

6. A workbench as claimed in Claim 5 in which the axes of the pivotal connections at the ends of the or each folding linkage coincide with the axis of the pivotal connection of the leading frame to the top structure, and with the axis of the pivotal connections of the rigid links to the trailing frame, respectively.

7. A workbench comprising a top structure which includes a pair of elongate vice beams, at least one of which is movable relative to the other for clamping of a workpiece therebetween, the vice beams having upper surfaces lying in substantially the same plane to form a working surface, and a collapsible supporting structure which includes a first generally flat frame and a second generally flat frame. which frames are pivotally connected to the top structure for swinging. movement about first and second pivot axes, respectively, between a collapsed position in which the frames and the top structure lie close together, with the first frame lying on the same side of the second frame as does the top structure, and an erected position in which the frames support the top structure above the ground, with the frames diverging from one another in the downward direction, and the supporting structure also including at least one link whose ends are connected to the first and second frames for pivoting relative to the first and second frames about third and fourth pivot axes, respectively, which axes, when the supporting structure is in its erected position, lie at a lower level than either of the first and second pivot axes, wih the third pivot axis at a level which is sufficiently below the level of the fourth pivot axis that the sum of the distances between the first and second pivot axes and between the first and third pivot axes is substantially equal to the sum of the distances between the second and fourth pivot axes and between the third and fourth pivot axes, so that, in the collapsed position of the workbench, both the first and fourth pivot axes can lie adjacent to the plane joining the second and third pivot axes.

8. A workbench as claimed in Claim 7 in which, with the frames in their erected position, the second pivot axis lies at a level which is sufficiently lower than the levelof the first pivot axis that, assuming that the attitude of the top structure is not changed from its erected position, the second frame can lie substantially horizontal in the collapsed position.

9. A workbench as claimed in Claim 7 or Claim 8 in which the first-mentioned sum of distances is slightly greater than the second-mentioned sum of distances, by an

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

long as they are involutes of the same curve, the vice beam 16 will be adequately guided.

Reference is made to Application Nos.

18687/77 Serial No. 1,582,867) and 18686/77 (Serial No. 1,582,866) which contain the same disclosure but claim different features.

WHAT WE CLAIM IS:- 1. A workbench comprising a top structure which includes a pair df substantially horizontal elongate vice beams, at least one of which is movable relative to the other for clamping of a workpiece therebetween, the vice beams having upper surfaces lying in substantially the same plane to form a working surface, and a supporting structure connected to the top structure and including front and rear generally flat frames pivoted at their upper ends by front and rear pivotal connections to the top structure for movement between erected and collapsed positions, the front and rear pivotal connections being disposed adjacent the front and rear of the top structure respectively. the frames, as viewed in side elevation when erected, being downwardly and outwardly splayed and having feet which in the erected position can engage a floor at points forward and rearward respectively of a plan projection of the top structure, the frames being arranged, when folding from the erected position to the collapsed position each to move in the same rotary direction with respect to the top structure with one frame leading the other, trailing, frame during such rotation, the frames being interconnected by rigid links, one at each end of the bench, which are pivoted to the frames by further pivotal connnections of which the pivotal connection to the leading frame is substantially lower on the leading frame than the pivotal connection of the link to the trailing frame such that, during collapsing, the trailing frame approaches the leading frame and, in the collapsed position, at least part of the trailing frame lies adjacent to the leading frame.
2. A workbench as claimed in Claim 1 in which the supporting structure is so arranged that, when in the collapsed position, the trailing frame lies substantially parallel to the leading frame.
3. A workbench as claimed in Claim 2 in which, when in the collapsed position, the trailing and leading frames lie substantially parallel to the working surface.
4. A workbench as claimed in Claim 1 or Claim 2 or Claim 3 in which at least one of the frames includes a pair of legs which are connected adjacent their lower ends by a horizontal foot-thrusting cross member.
5. A workbench as claimed in any of the preceding Claims in which the supporting structure includes at least one folding linkage comprising two parts connected by a pivot, the ends of the or each folding linkage being pivotally connected to the trailing frame and to the top structure, respectively.
6. A workbench as claimed in Claim 5 in which the axes of the pivotal connections at the ends of the or each folding linkage coincide with the axis of the pivotal connection of the leading frame to the top structure, and with the axis of the pivotal connections of the rigid links to the trailing frame, respectively.
7. A workbench comprising a top structure which includes a pair of elongate vice beams, at least one of which is movable relative to the other for clamping of a workpiece therebetween, the vice beams having upper surfaces lying in substantially the same plane to form a working surface, and a collapsible supporting structure which includes a first generally flat frame and a second generally flat frame. which frames are pivotally connected to the top structure for swinging. movement about first and second pivot axes, respectively, between a collapsed position in which the frames and the top structure lie close together, with the first frame lying on the same side of the second frame as does the top structure, and an erected position in which the frames support the top structure above the ground, with the frames diverging from one another in the downward direction, and the supporting structure also including at least one link whose ends are connected to the first and second frames for pivoting relative to the first and second frames about third and fourth pivot axes, respectively, which axes, when the supporting structure is in its erected position, lie at a lower level than either of the first and second pivot axes, wih the third pivot axis at a level which is sufficiently below the level of the fourth pivot axis that the sum of the distances between the first and second pivot axes and between the first and third pivot axes is substantially equal to the sum of the distances between the second and fourth pivot axes and between the third and fourth pivot axes, so that, in the collapsed position of the workbench, both the first and fourth pivot axes can lie adjacent to the plane joining the second and third pivot axes.
8. A workbench as claimed in Claim 7 in which, with the frames in their erected position, the second pivot axis lies at a level which is sufficiently lower than the levelof the first pivot axis that, assuming that the attitude of the top structure is not changed from its erected position, the second frame can lie substantially horizontal in the collapsed position.
9. A workbench as claimed in Claim 7 or Claim 8 in which the first-mentioned sum of distances is slightly greater than the second-mentioned sum of distances, by an

amount sufficient that the frames lie parallel to one another in the collapsed position.
10. A workbench as claimed in Claim 7 or Claim 8 or Claim 9 in which at least one of the frames includes a pair of legs, connected adjacent their ends remote from the top structure by a horizontal crossmember.
11. A workbench as claimed in Claim 10 in which the end or ends of the or each link associated with the legs of the frame or frames lie adjacent one or other of the legs, on the side of that leg closest to the other leg of the pair.
12. A workbench as claimed in Claim 11 in which the second frame includes a pair of legs and a horizontal cross member, and the or each link deviates from the straight line joining the third and fourth pivot axes, at least over the part of its length which lies adjacent the horizontal cross member of the second frame in the collapsed position of the workbench, the deviation being an upward deviation when seen in the erected position of the frames.
13. A workbench as claimed in Claim 10 or Claim 11 or Claim 12 in which each frame comprises a pair of legs connected, adjacent their ends remote from the top structure, by a horizontal cross member.
14. A workbench as claimed in any of Claims 7 to 13 in which the supporting strueture also includes means for locking the frames in their erected position.
15. A workbench as claimed in Claim 14 in which the locking means comprises at least one folding linkage comprising two parts connected by a pivot, the ends of the or each linkage being pivotally connected, respectively, to the second frame and to the top structure.
16. A workbench as claimed in Claim 15 in which the axes of the pivotal connections at the ends of the or each folding linkage coincide with the first and fourth pivot axes.
17. A workbench as claimed in Claim 15 or Claim 16 in which, as the frames are moved from their collapsed to their erected position, the or each folding linkage moves through a position in which its three pivots are collinear, and afterwards reaches a position in which further relative pivoting of the two parts of the linkage is prevented.
18. A workbench as claimed in Claim 15 or Claim 16 or Claim 17 in which the or each folding linkage is fitted with an overcentre action spring acting to hold the linkage in the erected position.
19. A workbench as claimed in any of the preceding Claims in which, when the frames are erected, they lie at equal but opposite angles to the vertical.
20. A workbench as claimed in any of Claims 7 to 19 in which the working surface lies substantially horizontal when the frames are erected, and lies generally parallel to the frames when the frames are collapsed.
21. A workbench as claimed in any of the preceding Claims in which the movement of the said one vice beam is produced by operation of one or both of a pair of clamping devices spaced along the length of the vice beams, which clamping devices are capable of independent operation, whereby the gap between the vice beams may taper along the length of the vice beams, and the said one vice beam being restrained against rocking about axes parallel to its length in response to the reaction force exerted by a workpiece on the said one vice beam.
22. A workbench as claimed in Claim 21 in which the top structure includes a pair of elongate supports which extend transversely to the length of the vice beams, one near each end of the vice beams, and below the level of the vice beams, and on which the vice beams are mounted, the frames being pivoted to the elongate supports.
23. A workbench as claimed in Claim 22 in which the vice beams project at their ends beyond the elongate supports for the vice beams.
24. A workbench as claimed in Claim 23 when appendant to Claim 13, in which each leg of the frames is pivoted to the side of one of the elongate supports which is remote from the other of the elongate supports, and, with the workbench erected and seen in plan view with the vice beams fully spaced apart, the legs do not underlie the gap between the vice beams.
25. A workbench as claimed in any of the preceding Claims in which the supporting structure includes four retractable extensions, two of the retractable extensions being mounted on one of the frames and the other two extensions being mounted on the other of the frames, in such a way that the extensions can be moved between an extended position in which feet of the extensions can contact the ground, and a retracted position in which, whether the frames are collapsed or erected, each pair of extensions lies generally within the plane of the frame to which the extensions of the pair are connected, the top structure being supported at a first height above the ground, when the frames are erected and the exten sions are extended, and the top structure being supported at a second, lesser, height above the ground, when the frames are erected and the extensions are in their retracted positions, collapsing and erecting of the frame being possible not matter whether the extensions are retracted or extended.
26. A workbench as claimed in Claim25 in which, at least when the retractable extensions are in their extended positions; their ground-engaging feet are spaced apart in the direction parallel to the axes of swinging of the frames by a distance greater than the spacing in the same direction of the parts of the workbench which engage the ground when the extensions are in their retracted positions.
27. A workbench as claimed in Claim 26 in which each retractable extension comprises a leg which is pivotable between the retracted position, in which it lies generally parallel to the axis of swinging of the frames, with its ground-engaging foot inboard of its other end, and the extended position, in which it extends obliquely outwards and downwards from the frame on which it is mounted.
28. A workbench as claimed in Claim 27 in which each retractable extension leg is provided with an overcentre action spring acting to hold it in whichever of its retracted and extended positions it has been placed.
29. A workbench as claimed in any of Claims 25 to 28 when appendant to Claim 13, in which the retractable extensions are mounted on the horizontal cross member of each frame.
30. A workbench as claimed in Claims 27 and 29 or Claims 27, 28 and 29 in which each horizontal cross member comprises a channel whose opening faces downwards when the workbench is in its erected position, and the retractable extension legs are of such a cross-section that they can be received within the channel, and are pivotally connected to the channel at their ends remote from their ground-engaging feet.
31. A workbench as claimed in Claim 30 in which, when the retractable extension legs are in their retracted position, their ground-engaging ends overlap.
32. A support or workbench as claimed in Claim 29 or Claim 30 or Claim 31 in which each hdrizontal cross member is readily detachable from the legs of its frame.
33. A workbench as claimed in any of Claims 29 to 32 in which each leg of the frame has a ground-engaging foot at its end remote from the top structure.
34. A workbench substantially as herein described, with reference to the accompanying drawings.