GB2053670A - Trestles - Google Patents

Abstract

The invention provides a trestle member for use in conjunction with a rigid bar such as 100 x 50 mm timber or 50 mm scaffold tubing to provide a trestle. The trestle member has a stem 10 carrying at one end a foot portion 11 and at the other end abutment surfaces spaced along the length of the bar 16, 27, at least one of which surfaces is provided by a bracket projecting laterally from the stem. In one embodiment, Fig. 6, a single bracket and the stem end between them provide spaced abutment surfaces, 23, 25 and in the other embodiments, e.g. Fig. 2, there are two spaced brackets 12, 13. The abutment surfaces are arranged to allow a rigid bar to be inserted therebetween and gripped thereby on reducing the included angle between the bar and the stem, i.e. the bar is inserted at an angle relative to the abutment surfaces and tilted relative thereto to be gripped therebetween. <IMAGE>

Description

SPECIFICATION Trestle member This invention relates to a memberfor use in constructing a trestle, that is, portable means for supporting a plank or similar working platform above the ground, for example, during building or decorating works.

Trestles are very widely used in the building and decorating industries to support planks typically 0.75 to 1 .2m (about 2 feet 6 inches to 4 feet above the ground, so as to allow bricklayers, plasterers or pain tersto reach with comfort to ceiling height in a room.

Such trestles are much more convenient to use than scaffolding, but the most common design of trestle nevertheless suffers from certain disadvantages.

The usual design of trestle comprises a generally rectangular frame having a pair of inverted U-shaped feet spaced across the width of the frame and projecting out of the plane of the frame for stability. The trestle is constructed from metal sections welded together, and in use one or more planks are laid across the upper horizontal frame member of two such trestles, spaced apart by a suitable distance.

In view of the quantity of metal required to make one of the just-described trestles, as well as the amount of fabrication involved, the trestles are somewhat expensive. They are also relatively heavy, and moreover do not stack easily when not in use owing to their shape. A further disadvantage is that when in use, not infrequently injuries can be inflicted by the projecting feet, and because planks are merely laid on the upper horizontal frame members, the stability of a plank supported by two trestles is not particularly good.

According to this invention, there is provided a trestle member comprising a stem, a foot portion disposed at one end of the stem, a first abutment surface projecting laterally from the stem at the other end thereof and a second abutment surface spaced from the first abutment surface, the abutment surfaces being arranged to allow a rigid bar to be inserted therebetween and then gripped thereby on reducing the include angle between the bar and the stem.

In one embodiment of the invention the abutment surfaces are provided each by a bracket projecting laterally from the stem. In this embodiment it is preferred forth two brackets to be spaced by a distance slightly in excess of 100 mm and to project laterally from the stem by approximately 50 mm so as to be capable of receiving therebetween a rigid bar in the form of a length of 100 x 50 mm timber with the 100 mm side vertical, which is one of the most common sizes of timber found on building sites.Preferably also at least one of the brackets, and conveniently the lower bracket, has a lip directed towards the other bracket on its free edge remote from the stem thereby to engage a face of the rigid bar and to restrain movement of the rigid bar laterally away from the stem once the bar has been gripped between the brackets, The foot portion preferably is in the form of a linear member attached to the stem so as to extend normally to the axis thereof. In the first embodiment of the invention the foot portion should extend in the same lateral direction as the brackets project, preferably to both sides of the stem.

Adjacent the bracket nearest the foot portion (the second bracket), the axis of the stem preferably is turned through an angle, so that when the brackets are locked to a rigid bar, they are spaced apart along the axis of the bar. Such an angle preferably is provided in the stem immediately adjacent the second bracket, on the side thereof nearer the other (first) bracket. A suitable included angle between the two parts of the stem axis is found to be from 1 20" to 160q and preferably 140 .

The stem, foot portion and second bracket in the first embodiment of this invention conveniently are made from tubular metal e.g. steel, welded as appropriate. The angle formed in the stem then can be made by cutting a V-shaped notch in the stem, bending the stem to close the notch and then welding together adjacent parts of the stem.

The first bracket is preferably in the form of a flat plate, welded or otherwise affixed to the stem with the plane of the plate at such an angle to the axis of the stem that when the trestle member is locked to a rigid bar of rectangular section, and predetermined dimensions, the plate lies parallel to and engaged with one surface ofthe bar. The trestle member thus is adapted specifically for use with a particular size and shape of rigid bar.

In another embodiment of the invention one abutment surface is provided by a bracket projecting laterally from the stem and held spaced longitudinally from said other end of the stem by at least one arm projecting beyond said end of the stem and the other abutment surface is provided by the said adjacent end of the stem. In this embodiment it is preferred for the bracket to be held by an arm on each side of the stem, and for the bracket to be spaced from the stem and the arm or arms arranged, so as to permit accommodation between the said abutment surfaces, and said arm or arms, of a rigid bar which is a pudlock or other short piece of scaffold tubing.

Preferably, the bracket provides a curved abutment surface, and the end of the stem may provide either a planar or a curved abutment surface, to co-operate with a tubular bar. Preferably, the surfaces if curved should be approximately 50 mm diameter to accommodate a standard 50 mm diameter scaffold tubing. Typically the bracket and arms are made in one piece from a sheet metal blank.

Again the stem and foot portion conveniently are made of tubular steel, welded as appropriate. In this other embodiment however, the foot portion should extend in a lateral direction at right angles to the direction in which the bracket projects.

Preferably, the bracket and arms are formed in one piece from steel plate bent to an arched cross section and preferably are fixed by welding to the end of the stem remote from the foot portion.

In a further embodiment of the invention the abutment surfaces again are provided each by a bracket, one bracket projecting laterally from the stem atthe other end thereof and another bracket projecting laterally towards the stem from a stem portion lying substantially parallel with the stem and projecting from the free edge of said one bracket remote from the stem. This embodiment of the invention is especially suitable for forming in one piece from tubular metal by bending and preferably the foot portion, stem, stem portion and brackets are so formed.

As with the first embodiment of the invention the two brackets are preferably spaced by a distance slightly in excess of 100 mm and project from or towards the stem by approximately 50 mm so to be capable of receiving therebetween a rigid bar in the form of a length of 100 x 50 mm timber.

Preferably said other bracket has a lip directed towards said one bracket on its free edge remote from the stem portion thereby to engage a face of the rigid barandto restrain movementofthe bar laterally away from the stem portion once the bar has been gripped between the brackets.

Preferably the axis of the stem portion is at an angle to the axis of the stem so that when the brackets grip a rigid bar inserted therebetween they are spaced apart along the axis of the bar. A suitable included angle between the axis of the stem portion and the axis of the stem is gain from 120 to 1600, and preferably 1400.

Again as with the first embodiment the foot portion is preferably linear, and preferably extends in the same lateral direction as the brackets project, preferably to both sides of the stem.

By having a tubular stem, the part thereof between the foot portion and the bracket or brackets may be made telescopic: for instance this part of the stem may be made in two portions one of which may slide axially within the other. Then, by providing means to lock the stem portions in a plurality of relative positions a trestle member of adjustable height can conveniently be made. For example, this may be achieved by providing a series of holes spaced axially and extending diametrically through one portion, any one hole of which may be brought into registration with a single diametric hole in the other portion by relative axial sliding movement. When in registration, the portions may be locked together by passing a pin orboltthroughthre registering holes.

The trestle member of this invention may be used in a variety of ways, with rigid bars of various lengths. A free-standing trestle may be made by locking two such trestle members to a single rigid bar, in which the stems of the two trestle members can lie on opposed sides of the bar, to add to the stability of the trestle. For a relatively short trestle the stems may then cross over each other, whereas for a longer trestle the trestle members may be spaced along the length of the bar. Another possibil ity is for a single trestle member to be used in con junction with a single bar, the member being locked to the bar and then the combination being leant against a wall with the end of the bar and the top end of the trestle member engaging the wall. For stability, the bar should not project horizontally beyond the. position of the foot portion on the ground.

Two or more trestles arranged as just-described may be disposed at the workplace, spaced by a suitable distance to support one or more planks resting on the bars thereby to provide an elevated working platform.

By way of example only specific embodiments of this invention will now be described, reference being made to the accompanying drawings, in which: Figure lisa side view of one embodiment of a trestle member in accordance with this invention; Figure 2 is a detail view on an enlarged scale of the upper part of the trestle member of Figure 1, engaged with a rigid bar; Figure 3 shows how two trestle members as shown in Figure 1 may be engaged with a rigid piece of timber to make a free-standing trestle; Figure 4 shows an alternative arrangement of two such trestle members and a rigid piece of timber; Figure 5 shows how a support for a plank may be made from one trestle member as shown in Figure 1 together with a length of timber;; Figure 6 shows how a support for a plank may be made from one trestle member using another embodiment of a trestle member in accordance with this invention together with a length of scaffold tubing; Figure 7 is a detail view on an enlarged scale of the upper part of the trestle member of Figure 6; Figure 8 is a plan view of a metal blank for use in forming the bracket of the trestle member of Figure 6; Figure 9 is a detail view on an enlarged scale of the upper part of a variant of a trestle member as shown in Figure 6; Figure 10 is a detail view on an enlarged scale of the upper part of another variant of a trestle member as shown in Figure 6; Figure 11 is a side view of a further embodiment of a trestle member in accordance with the invention; and Figure 12 is a view in the direction of the arrow A ofthetrestle member of Figure 11.

Referring to Figures 1 and 2 ofthe drawings. there is shown a trestle member comprising a tubular metal stem 10 having welded to the lower end thereof a tubular metal foot 11, the axis of the foot extending normally to the axis of the stem, to project from both sides thereof. Welded to the other end of the stem 10 is a metal plate 12, projecting laterally to one side only of the stem in a direction generally parallel to the axis of the fcwot 10. Atubular stub 13 is also welded to the stem 10, spaced a short distance from the plate 12 and extending in generally the same direction as the plate. The free end of the stub 13 is closed by a plate 94, upstanding from the stub 13 towards the plate 12, so as to form a lip 15. The plate 12 serves as a first bracket and the stub 13 as a second bracket, between which a length oftimber can be located, as shown in Figure 2.

Immediately above the stub 13, the axis of the stem is angled, preferably by cutting, bending and then welding the stem 10. The included angle introduced in this way into the stem is advantageously substantially 140s, as shown in Figure 3 to 5.

The spacing of the first and second brackets, as well as their specific dimensions are preferred to be such that a length of 50 x 100 mm timber can be fitted therebetween, as shown in Figure 2, with the timber on edge. The tubing itself from which the stem is made is preferred to be steel tube, of 40 mm outside diameter, and 4 mm wall thickness. The foot 11 has an overall length of 500 mm, and is positioned such that the distance from the centre of the stem to the free end of the foot on the same side as the brackets is substantially 270 mm.

The trestle member described above can be used in a variety of ways. In Figure 3, two such trestle members are shown in use with a 700 mm length of 50 x 100 mm timber 16, each trestle member being locked to the length oftimberto form a free-standing plank support. To iock each trestle member to the timber 16, the timber is rested on the stub 13 and engaged between the lip 15 and the stem 10; then the trestle member is pivotted about the stub 13 until the plate 12 bears on the upper surface of the timber.

In this disposition, the trestle member lies at approximately 67" to the timber axis. The two trestle members are engaged with the timber 16 from opposed sides, and in this way a simple free-standing support easily can be made. By using two such supports, planks can be carried at a height above the ground of typically 1200 mm.

In the arrangement shown in Figure 3, the stems of the two trestle members cross over each other, to give a narrow plank support suitable for use, for instance, in hall-ways. Figure 4 shows an alternative arrangement, using a much longer length of 50 x 100 mm timber. Whilst considerable lengths of timber could be used to support many planks, thereby giving a large elevated working platform, it is recommended with the particular design of trestle member described above that the separation of the feet of the trestles should not exceed 2 m.

As shown in Figure 5, a plank support may be made from a single trestle member of this invention in combination with a length of 50 x 100 mm timber, by leaning the combination against a wall 18. In this case, the plate 12 at the upper end of the trestle as well as one end of the timber 19 should contact the wall, the timber should extend generally horizontally, and the timber length should not extend away from the wall further than the trestle foot 10. Thus, with the particular configuration described above, the timber length should not exceed 700 mm. By using two such arrangements spaced apart, a plank 30may be supported safely, close to a wall, provided that the plank is positioned as shown between the stub 13 and the foot 11.

Referring to Figures 6 and 10, there is shown another trestle member again comprising a tubular metal stem 10 having welded to the lower end thereof a tubular metal foot 11 projecting from both sides of the stem. Welded to the other end of the stem 10 is a metal bracket member 21 which provides two arms 22 holding a bracket 23 spaced laterally and longitudinally from end 24 of the stem 10.

The end 24 has a flat profile 25, cut at a slight angle to the normal to the stem axis and the bracket 23 is curved in cross-section, so that the upper parts of the arms 22, the bracket 23 and the flat profile 25 of end 24 between them define a space 26 into which a pudlock or other short piece of 50 mm scaffold tubing 27 may be inserted and gripped between bracket 23 and end 24.

As shown in Figure 8 the arms 22 and bracket 23 are formed by bending a steel plate blank comprising wings 22' corresponding to arms 22 and a connecting portion 23' corresponding to bracket 23.

The trestle member of Figures 6 to 8 may be used singly as shown in Figure 6, that is to say in a manner similarto that shown in Figures, or in combination with another trestle member as shown in Figure 4, the timber in each case being replaced by a scaffold tube. Alternatively, where it is desired to use the trestle member of Figures 6 to 8 in combination with another trestle member as shown in Figure 3, it is necessary to employ a variant as shown in Figure 9 where the stem is provided with a bend 31 so that each end 24 is offset by a distance equal to half a stem diameter, whereby in the crossed over configuration the spaces 26 are in line.

For use with the usual 50 mm scaffold tube the space 26 will have a width and height of approximately 50 mm and conveniently the stem 10 and foot 11 are made of 50 mm tubing. Where the stem 10 is made of tubing of smaller diameter e.g. 30 mm or 40 mm tubing, the end of the stem which carries bracket member 21 may be crushed to provide the necessary width as shown in Figure 10. Also, in any of the trestle members of this embodiment the top of the stem can have a curved profile 28 as shown in Figure 10.

Referring to Figures 11 and 12, there is shown a further trestle member formed in one piece by bending a metal tube. Again the trestle comprises a stem 10 having a foot 11,the stem carrying a laterally projecting bracket 33. At its free edge remote from the stem 10 the bracket 33 carries a stem portion 34 which in turn carries a second bracket 35 projecting towards the stem. As shown the axis of the stem portion 34 is at an angle (preferably of 140 ) to the axis of the stem 10 so that when the brackets grip a timber bar inserted therebetween they are spaced apart along the axis of the bar.

The trestle member shown in Figures 11 and 12 may be used singly in the manner shown in Figure 5, or in combination with another trestle member in the manners shown in Figures 3 and 4.

When the trestle members are to be stored, it will be appreciated that due to their simple shape, many can be packed into a relatively small space. The trestle members are also relatively light in weight, and simple to manufacture. The timber or scaffold tubing used in conjunction therewith is most commonly available on building sites, and in the case of timber can be specially prepared lengths or merely scrap off-cuts, utilised as an when required.

Thus, it can be seen from the above that the trestle member of the invention can reduce the abovementioned disadvantages of the common design of trestle, and is convenient to use.

Claims (30)

1. Atrestle member comprising a stem, a foot portion disposed at one end of the stem, a first abutment surface projecting laterally from the stem at the other end thereof and a second abutment surface spaced from the first abutment surface, the abutment surfaces being arranged to allow a rigid barto be inserted therebetween and then gripped thereby on reducing the included angle between the bar and the stem.

2. Atrestle member according to claim 1, wherein the abutment surfaces are provided each by a bracket projecting laterally from the stem.

3. Atrestle member according to claim 2, wherein the two brackets are spaced by a distance slightly in excess of 100 mm and project laterally from the stem by approximately 50 mm so as to be capable of receiving therebetween a rigid bar in the form of a length of 100 x 50 mm timber.

4. A trestle member according to claim 2 or claim 3, wherein at least one of the brackets has a lip directed towards the other bracket on its free edge remote from the stem thereby to engage a face of the rigid bar and to restrain movement of the bar laterally away from the stem once the bar has been gripped between the brackets.

5. A trestle member according to any one of claims 2 to 4, wherein the foot portion is a linear member attached to the stem so as to extend normally to the axis thereof and at least in the same lateral direction as the brackets project.

6. A trestle member according to any one of claims 2 to 5, wherein adjacent the bracket nearest the foot portion the axis of the stem is turned through an angle so that when the brackets grip a rigid bar inserted therebetween they are spaced apart along the axis of the bar.

7. Atrestle member according to claim 6, wherein the angle is provided on the stem immediately adjacent the bracket nearest the foot portion on the side thereof nearer the other bracket.

8. A trestle member according to claim 6 or claim 7, wherein the included angle between the two parts of the stem axis is from 120" two 1 60".

9. Atrestle member according to any one of claims 2 to 8, wherein the stem, foot portion andlor the bracket nearest the foot portion are made from tubular metal.

10. Atrestle member according to claim 9 when dependent on any one of claims 6 to 8, wherein the angle formed in the tubular metal stem is made by cutting a V-shaped notch in the stem, bending the stem to close the notch and then welding together adjacent parts of the stem.

11. Atrestle member according to any one of claims 6 to 10, wherein the bracket remotest from the foot portion is in the form of a flat plate affixed to the stem with the plane of the plate at such an angle to the axis of the stem that when the trestle member is locked to a rigid bar of rectangular section the plate lies parallel to and engaged with one surface of the bar.

12. A trestle member according to claim 1, wherein one abutment surface is provided by a brac ket projecting laterally from the stem and held spaced longitudinally from said other end of the stem by at least one arm projecting beyond said end of the stem and the other abutment surface is provided by the said adjacent end of the stem.

13. Atrestlememberaccordingtoclaim 12, wherein the bracket is held by an arm on each side of the stem.

14. A trestle member according to claim 13, wherein the bracket and arms are made in one piece from a sheet metal blank.

15. A trestle member according to any one of claims 12 to 14, wherein the bracket provides a curved abutment surface to co-operate with a tubu lar bar.

16 A trestle member according to any one of claims 12 to 15, wherein the said end of the stem provides a curved abutment surface to co-operate with atubular bar.

17. A trestle member according to any one of claims 12 to 16, wherein the bracket and the said end of the stem are spaced longitudinally by about 50 mm to accommodate between the said abutment surfaces, and said arm or arms, a rigid bar which is 50 mm scaffold tubing.

18. A trestle member according to any one of claims 12 to 17, wherein the foot portion is a linear member attached to the stem so as to extend normally to the axis thereof and in a lateral direction at right angles to the direction in which the bracket projects.

19. Atrestle member according to any one of claims 12 to 18, wherein the stem and foot portion are made from tubular metal.

20. A trestle member according to claim 19 when dependent on any one of claims 13 to 18, wherein the end of the tubular metal stem remote from the foot portion, in a direction at right angles to the direction in which the bracket projects, is formed so as to provide a seating for the two arms, the seating spacing the arms apart a greater distance greater than the diameter of the tubular stem.

21. Atrestle member according to any one of the preceding claims, wherein the stem is tubular and in two parts, one of which carries the bracket or brackets, and the other of which carries the foot portion, one stem part being slidable axially within the other stem part, and including means to lockthe stem parts in a plurality of relative positions to provide a trestle member of adjustable height.

22. Atrestle member according to claim 1 or claim 21 when dependent on claim 1, wherein the abutment surfaces are provided each buy a bracket, one bracket projecting laterally from the stem at the other end thereof and another bracket projecting laterally towards the stem from a stem portion lying substantially parallel with the stem and projecting from the free edge of said one bracket remote from the stem.

23. A trestle member according to claim 22, when dependent on calim 1, wherein the foot portion, stem, stem portion and brackets are formed in one piece from tubular metal by bending.

24. A trestle member according to claim 22 or claim 23, wherein the two brackets are spaced by a distance slightly in excess of 100 mm and project from or towards the stem by approximately 50 mm so as to be capable of receiving therebetween a grid bar in the form of a length of 100 x 50 mm timber.

25. A trestle member according to any one of claims 22 to 24, wherein said other bracket has a lip directed towards said one bracket on its free edge remote from the stem portion thereby to engage a face of the rigid bar and to restrain movement ofthe bar laterally away from the stem portion once the bar has been gripped between the brackets.

26. A trestle member according to any one of claims 22 to 25, wherein the axis of the stem portion is at an angle to the axis of the stem so that when the brackets grip a rigid bar inserted therebetween they are spaced apart along the axis of the bar.

27. A trestle member according to any one of claims 22 to 26, wherein the included angle between the axis of the stem portion and the axis of the stem is from 1200to 1600.

28. A trestle member according to claim 1 and substantially as hereinbefore described with reference to and as illustrated in Figures 1 to 5 of the accompanying drawings.

29. Atrestle member according to claim 1 and substantially as hereinbefore described with reference to and as illustrated in Figures 6 to 10 of the accompanying drawings.

30. Atrestle member according to claim 1 and substantially as hereinbefore described with reference to and as illustrated in Figures 11 and 12 of the accompanying drawings.