FIELD OF INVENTION

This invention relates to a bricklayers' trestle.

BACKGROUND ART

The following references to and descriptions of prior proposals or products are not intended to be, and are not to be construed as, statements or admissions of common general knowledge in the art. In particular, the following prior art discussion should not be assumed to relate to what is commonly or well known by the person skilled in the art, but to assist in the inventive process undertaken by the inventor(s) and in the understanding of the invention.

Previous bricklayers' trestles have been described as having a rectangular centre frame with two swing style A-frames permanently attached to the centre frame. The heavy combination of components is difficult to transport and manoeuvre. The swing mounted A-frame stands are a finger-crush hazard as the A-frames are prone to swinging towards a closed angle with the centre frame. Pins are inserted through the A-frames and centre frame to lock the trestle in position with the centre frame providing a rest for a platform at a certain height.. One disadvantage is that the pins may be lost. Another disadvantage of the swing-style A-frames is the inefficiency in transportation due to the large area taken up by the three-part trestles in which the A- frames are rotatably attached and lie in a bulky storage mode outside the area of the rectangular centre frame. Furthermore, previous bricklayers' trestles have been described as heavy and costly due to the manufacturing requirements and parts used.

An object of the present invention is to ameliorate the aforementioned disadvantages of the prior art or to at least provide a useful alternative thereto.

STATEMENT OF IN VENTION

The invention according to one or more aspects is as defined in the independent claims. Some optional and/or preferred features of the invention are defined in the dependent claims.

Accordingly, in one aspect of the invention there is provided:

A trestle for supporting a temporary platform including:

A centre frame and at least two side frames adapted to be spaced in a standing position relative to each other with the centre frame inteiposed there between, each side frame including a substantially upstanding member and at least two ground-contacting supports or at least one ground contacting support adapted to support the upstanding member at spaced ground-contacting points or regions, the centre frame having a pair of spaced upright members each adapted to align substantially upright and to align with the upstanding members of the side frames,

each spaced upright member adapted to engage one of the upstanding side frames members,

wherein the engagement of the upstanding side frame members with the upright centre frame member includes:

a horizontally spaced pair of sets of lugs, in which one or more lugs of each set of lugs are arranged in a substantially vertically aligned series; and

a horizontally spaced pair of sets of recesses, in which the one or more recesses of each set are arranged in a substantially vertically aligned series,

each set of lugs being adapted to engage with a corresponding one of the sets of recesses,

whereby:

the centre frame relative to the side frames can be set at any one of a variety of incremental and different positions to vary the height of the platform ; and

Trestle

The trestle comprising the centre frame engaged to the side frames is preferably adapted to stand alone. The trestle may be a stand-alone frame. The trestle

components may be portable. The trestle may be collapsible. The trestle may be of the type commonly used by bricklayers, wall wrapping workers, painters and the like. The trestle preferably includes a collapsible frame. The collapsible frame may be capable of folding or disassembly to achieve a flat set of components having good stackability for transport and storage.

Temporary platform

The platform may be a substantially flat and/or reinforced panel or modular set of panels. The platform is most simply in the form of a thick and/or rigid panel, sheet, or board. The platform may be made of timber, plastic, steel or aluminium checker plate.

The platform ideally has one or more brackets to locate an upper support section of the centre frame and to limit longitudinal movement of the platform relative to the centre frame.

Centre frame The centre frame may include a variety of different configurations and includes the upper support section adapted to provide stable support for the platform, by means of either at least two platform-supporting members or at least one platform supporting member adapted to support the platform at spaced platform underside-contacting points or regions. Preferably the platform supporting member is a flat bar. Preferably, the platform supporting member includes side bamers to limit lateral movement of the platform and/or to trap side edges of the platform against lateral and/or vertical movement relative to the centre frame. Preferably, the barriers are in the form of upstanding side flanges or brackets adapted to limit sideways travel of the platform relative to the centre frame.

The centre frame may comprise a substantially rectangular frame. The centre frame may include one or more lateral or diagonal braces to rigidify the centre frame. The centre frame may have upper and lower vertically spaced substantially horizontal bars between which extend the upright members.

The centre frame preferably substantially lies in a centre frame plane.

Side frames

The side frames each preferably include at least one diagonal stmt or brace. The side frames each preferably include at least one substantially horizontal bar, stmt or brace at its lower end to fix the spacing of the at least two ground-contacting supports, points or regions. Preferably, the side frames each include a pair of spaced ground- contacting supports or feet. The ground contacting supports may extend substantially transversely relative to a plane in which the centre frame is adapted to be positioned. The upstanding member may be positioned between the at least two ground- contacting supports, points or regions, so that the load to be applied through the upstanding member is stably supported by the spaced supports or points on the ground. Preferably, the at least one diagonal strut or brace and the upstanding member extend upwardly in a progressively convergent alignment. Preferably, the at least one diagonal strut or brace and the upstanding member converge and join at an apex, so that the side frames have a wide supporting base and a narrow upper end for optimal weight distribution and stability.

Upstanding members

The upstanding member of each of the side frames preferably comprises a post. The upstanding members are preferably substantially linear. The upstanding members preferably comprise upstanding posts adapted to engage the upright members of the centre frame. The upstanding members are preferably rigid and have high

compression strength. Ideally, the upstanding members are formed from metal, such as galvanised metal or steel. The upstanding members may be solid or hollow.

Preferably, the upstanding members are made by a tubular extruded or cast manufacturing process. The upstanding members preferably are in the form of hollow circular or square-sectioned metal members.

Upright members

The upright members of the centre frame may be formed similarly to the upstanding members.

Engagement

Engagement of the upstanding side frame members with the upright centre frame members may be achieved by manually orienting the side frames in an upstanding position. The side frames may be made to face each other and to be spaced correctly to allow interposition and engagement of the centre frame. The centre frame may then be lifted and manoeuvred into position to engage the side frames in a stable trestle structure. A second mirror image or identical trestle may be erected and positioned parallel to the first trestle at a location sufficiently spaced from the first trestle in a direction normal to the plane of the first centre frame and a distance corresponding to the required spacing of trestles for the particular length of the platform to be supported.

Spaced pair of sets of lugs and recesses

One or more of the lugs of the sets of lugs and/or one or more of the recesses of the sets of recesses may extend laterally from the side of the corresponding upstanding member or the corresponding upright member.

Each of the sets of lugs may be attached to, or form part of, one of the side frames whereby the sets of recesses will be attached to, or form part of, the centre frame.

Preferably, however, the sets of lugs may be attached to, or form part of, the centre frame whereby each of the sets of recesses will be attached to, or form part of, one of the side frames.

The lugs and recesses may be shaped to resist rotation of one of the lugs engaged in one of the recesses. The lugs and recesses may be shaped to resist rotation of one of the lugs engaged in one of the recesses about a substantially vertical axis. The lugs and recesses may be shaped to resist rotation of one of the lugs engaged in one of the recesses about a substantially horizontal axis. The recesses may define a hollow square, triangular or other shape with at least one planar wall, the planar recess wall being adapted to be opposed or abutted by a corresponding flat outer surface of a lug engaged therein. Preferably, the recesses define a substantially rectangular, or more specifically, a substantially square cavity, channel or through-hole that may or may not be open ended or even open sided, provided that the lug is trapped in the recess against lateral relative displacement once engaged therein.

The lug may have an outwardly extending arm, including a plate and/or bracket, from which extends along a substantially vertical axis (when the trestle is upstanding) a lug protrusion. The protrusion may substantially extend in one direction and may have a longitudinal axis. The protmsion may be adapted to enter the recess in the direction of the protrusion axis. The extent of travel of the protmsion into the recess may be limited by the arm abutting one end of a wall of the recess.

The recess may be of consistent shape and dimension throughout its length or may include converging walls. The recess walls may be or pyramidal or conical in shape. The protmsion may be complementarily shaped with a narrow entry head and diverging side walls extending to a wide base that limits the axial or vertical limit of travel of the protrusion in the recess.

The protmsions are, in a particularly preferred embodiment, tapered downwardly to facilitate entry of the lug into the recess. The upper portion of the protmsion may be at least as wide in diameter or width as the entrance into cavity defined by the recess wall, so that the entry of of the protmsion into the recess proceeds downwardly until the outer wall of the protmsion meets the inner wall surface of the recess to achieve a snug fit with minimal play.

The outer wall of the protmsion may have a lower tapered section that expands to meet a contiguous cylindrical wall forming an upper section of the protrusion. The tapered end of the protrusion is used to locate the terminal nose portion of the tapered lower section and slid into the recess. The upper cylindrical wall section meets the recess cavity in a snug fit, so that a length of the upper section of the protrusion fits snugly along a substantial proportion of its length in a tight fit with the recess inner wall surface.

Gravity assists to retain the lugs in their corresponding recesses. However, preferably the snug fit of the upper section of the protrusion provides a positive connection that does not easily displace whether or not a temporary upward force is applied to a lug relative to a corresponding recess. To intentionally remove a series of lugs from their corresponding recesses, a worker may use an impact tool such as a hammer to apply upward force as required to the lower beam, preferably immediately underneath the zone where the vertical post meets the beam.

The protrusions are generally spaced from the outer surface of the vertical posts to which they are mounted. The protrusions depend downwardly from a laterally extending arm attached to the corresponding vertical post.

Alternatively, the protmsion is a square sectioned section of tube welded or otherwise fastened onto the upstanding member. The recess may be similarly constructed and comprise an attached section of tube. The tube forming the recess may be of sufficient internal dimensions to engageably receive the protrusion in a substantially tight fit, sufficiently tight to limit undesirable play but still enabling easy removal when required. Advantageously, the protmsion may be polygonal, such as square, in cross- section, or may have a longitudinal key, whereby to restrict rotation of the lug in the recess about the lug's longitudinal axis. Each set of recesses may comprise at least one recess that is sufficiently long whereby a correspondingly long protmsion will be sufficient to ensure that even if only a single lug from a set is engaged in a recess of a complementary set, the engagement is stable against rotation about a substantially horizontal axis because of the provision of spaced contact points between the lug and the recess.

Preferably, each set of recesses includes a plurality of recesses, preferably at least three. The set of recesses preferably includes a sufficient number of recesses. Also, each set of lugs preferably includes a plurality of protrusions, preferably two, and most preferably three. The set of recesses preferably includes a sufficient number of recesses to provide a range of incremental height positions for the centre frame. Each of the sets of lugs preferably includes between two and three protrusions.

The multiple lugs and recesses in each respective set preferably are arranged linearly so that they are adapted to align substantially vertically with respect to each other. The multiple lugs and recesses in each respective set preferably are equi-spaced from each other. The provision of a multiple of substantially vertically spaced engagement connections between the lugs and the recesses provides a rigid and strong engagement of the centre frame with the side frames with minimal or virtually no play between the lugs and recess.

The protmsions preferably depend downwardly from the plate and may be located at or near the lower end of the upright member. The plurality of recesses of each set are preferably arranged along substantially the full length of the upstanding members.

The trestle of the invention is formed easily and safely with minimal finger-crush hazards. The centre frame and side frames are separable and therefore lighter than an arrangement in which the components of the centre platform support frame. The side support stand frames are advantageously separable and able to be manoeuvred separately unless in use. The components are easier to stack, than the prior art swing A-frame, for example. BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be better understood from the following non-limiting description of preferred embodiments, in which:

Figure 1 is 1 is a front elevation of a centre frame and a side elevation of a side frame according to a first embodiment of the invention exploded to show how the centre frame engages with the side frame;

Figure 2 is a front view of a trestle according to the first embodiment;

Figure 3 is a perspective view of a portion of the trestle according to the first embodiment;

Figure 4 is a rear perspective view of the centre frame according to the first embodiment;

Figure 5 is a perspective view of a centre frame 120 according to a second embodiment of the invention;

Figure 5 A is a magnified view of a protrusion shown in Figure 5;

Figure 6a is a side elevation of the centre frame shown in Figure 5;

Figure 6b is a top plan view of the centre frame shown in Figure 5; and

Figure 6 is a side elevation of the centre frame shown in Figure 5.

DETAILED DESCRIPTION OF THE DRAWINGS

Preferred features of the present invention will now be described with particular reference to the accompanying drawings. However, it is to be understood that the features illustrated in and described with reference to the drawings are not to be construed as limiting on the scope of the invention.

Referring to Figs. 1 - 4, there is shown components of a first embodiment for a trestle 10 adapted to form one end of a support for a platform 5 shown in ghosted lines. The trestle 10 includes a centre frame 20 and at least two side frames 40. Each side frame 40 has at least two ground-contacting supports 50. The ground contacting support 50 may be a horizontal bar adapted to extend flat along the ground surface. Alternatively, the at least one ground contacting support 50 is adapted to support the side frame 40 at spaced ground-contacting points or regions 50.

The at least two side frames 40 are adapted to be spaced in a standing position relative to each other with the centre frame 20 interposed therebetween. Each side frame 40 is adapted to support a substantially upstanding member 42 (hereinafter referred to as upstands 42). The centre frame 20 has a pair of spaced upright members 24a,b, (hereinafter referred to as uprights 24a,b). Each upright 24a,b is adapted to align substantially upright and to align with the upstands 42 of the side frames 40. Each spaced upright 24a,b is adapted to engage one of the upstands 42. The engagement of the upstands 42 with the uprights 24a,b includes:

a spaced pair of sets of lugs 62, in which the one or more lugs 60 of each set are arranged in series; and

a spaced pair of sets of recesses 72, in which the one or more recesses 70 of each set are arranged in series, each set of lugs 62 being adapted to engage with a corresponding one of the sets of recesses 72.

The engagement of one of the sets of lugs 62 with a corresponding set of recesses 72 is in a linear arrangement in which the protrusion axes of a set of lugs 62 are substantially in line. One of the sets of lugs 62 is aligned in a substantially vertical column with the lugs of the set being substantially vertically spaced. The centre frame 20 relative to the side frames 40 can be set at any one of a variety of

incremental and different positions to vary the height of the platform 5.

The centre frame 20 comprises a substantially rectangular frame. The centre frame 20 includes angle and square sections to form a base bar 22 formed from an L-section, side posts forming the uprights 24a,b are made from square section. An upper substantially horizontal support bar 26 is adapted to directly support the platform 5. The upper support bar 26 includes, at each of its ends, a pair of laterally spaced barriers 27. The barriers 27 are in the form of upstanding side flanges or brackets that are adapted to limit unintended sideways movement or travel of the platform 5 relative to the centre frame 20. The underside of the platform may include 2 or more transverse inverted channels, typically in the form of attached channel strips, to fix the platform 5 relative to the upper support bar 26. Each upper support bar 26 with the spaced barriers defines a transverse channel adapted to cradle the platform 5.

The upper and lower bars 22,26 are braced with one or more diagonal braces 28 formed from a metal strap. The components 22- 28 may be respectively joined by welding, or by fasteners, such as nuts and bolts.

The side frames 40 include an A-frame structure similarly formed from square and L- sections welded or otherwise joined together. Each side frame 40 includes the upstand in the form of an upstanding post 42. The upstand 42 is braced by a lower L-section cross bar 44. Joined at an upper apex 46 and depending and diverging downwardly is a pair of support legs 48. The support legs 48 each terminate in a ground-contacting foot 50, each side frame 40 thereby having a pair of spaced ground contacting feet 50 aligned at right angles to the vertical plane in which the centre frame 20 is adapted to be positioned. The engagement means 36 includes lugs 60 and recesses 70. The lugs 60 are aligned in a spaced pair of sets of lugs 62. The lugs 60 in each set are equally spaced apart and aligned in a linear series of lugs. The lugs 60 each include an L-shaped bracket 64 attached to the outward facing surface 32 of each of the upright posts 24a,b. This is to provide an outwardly and laterally extending arm 65 lying in substantially the same plane as the centre frame 20 substantially lies in. Preferably, each set of lugs 62 includes two or three lugs 60. Downwardly depending from each arm 65 is the lug 60 in the form of a protrusion. The protrusion is formed from a hollow short square section of tube welded to the underside of the arm 65 and having dimensions sufficient to be received in the recess 70. The protrusions 60 are spaced from the upright posts 24a,b so that there is a gap between an inner wall of the protrusion 60 and an opposed outer wall of the upright post 24a,b. The gap is dimensioned to receive a portion of a wall of the recess 70.

The recesses 70 are each attached to the inside surface 43 of the upstanding post 42. Each recess 70 forms part of one of the sets of recesses 72 arranged in linear, substantially coaxial, alignment along a side and along the length of the upstanding post 42. The spacing between adjacent recesses 70 in each series 72 is substantially the same as for the lugs 60 in a corresponding series of lugs 62. The recesses 70 are each formed from short hollow, open-ended square sections. Each recess 70 is dimensioned to substantially coaxially receive within its cavity a corresponding lug 60.

Accordingly, as shown in Fig. 1 , the centre frame 20 may be lifted up and positioned so that each series of lugs 62 is placed into a corresponding series of recesses 72 at any one of six different heights in the embodiment 10 shown. Accordingly, where there are three lugs 60 per series 62 and eight recesses 70 per recess series 72, there are 6 possible heights of the centre frame 20 available for selection. On similarly assembling an identical trestle (not shown) and spacing the respective trestles 10 and their centre frames 20 apart and facing each other in parallel substantially vertical planes, the platform 5 may be safely supported at or near each of its ends or intermediate its length as desired. The platform 5 may therefore rest or be positively attached on the upper bars 26 of each trestle 10 to form a horizontal work platform for a worker needing an elevated area to stand on. If the ground surface is uneven or inclined, a first of the centre frames 20 of one of the respective spaced trestles 10 situated in a downward direction of an incline may be set at a higher level on the corresponding upstands 42 and a second of the centre frames 20 may be set at a lower level on the corresponding upstands 42 whereby to achieve a substantially horizontal platform 5. Referring to the second embodiment shown in Figures 5-6c, there is shown an alternative centre frame 120, similar in construction and dimensions compared to centre frame 20 and engageable and cooperable with side frames 40 shown in Figures 1 -4. Similar features share the same reference numerals (+100) with reference to the description of the first embodiment. In the second embodiment, the centre frame 120 includes two sets 162 of three lugs 160 welded to the outer side walls of spaced vertical posts 124a, b. Each set 160 of lugs 162 includes three lugs sharing a common longitudinal axis 161 with the other lugs 160 in each set 162, so that then inserted into engagement with a corresponding set 72 of recesses 70, 160 and recesses 70 are in coaxial alignment whereby to provide a strong engagement with three rigid points of connection spaced along the axis 161.

Each protrusion 160 is mounted to a side wall 124a,b by welding a laterally extending arm or bracket 165. The bracket 165 comprises an L-shaped section having a mounting panel 166 welded to the substantially vertical post 124a,b and having the laterally extending arm 165. The laterally extending arm 165 extends substantially normal to the plane of the outer surface of the vertical post 124a,b in cantilever fashion. The laterally extending arm 165 provides a laterally extending plate lying in a substantially horizontal plane.

The lug depends downwardly from the underside of the lateral arm 165 and is held in place by a weld, bolt or pin.

Each lug 160 comprises an upper, substantially cylindrical, portion 169 having a width or diameter closely corresponding (but marginally smaller by less than 1mm) to the internal width or diameter of the corresponding recess 70. The upper section 169 is therefore adapted to sit snugly within the walls of the recess 70 in the engaged position. However, the lug 160 further includes a lower section 168 contiguous with the upper section 169 that transitions to a truncated conical shape terminating in a lower narrower nose 168a.

Accordingly, the tapered lower section 168 facilitates the location of the lug 160 in a corresponding recess 70 by providing the narrow nose 168a that is substantially narrower than the upper entrance 70a of the recess 70. Ease of registration of each lug 160 in each corresponding recess 70 is particularly highlighted where there are multiple lugs 160 in each set of lugs 162, such that, in the embodiments shown, multiple lugs 160 must be co-located in their respective recesses 70 simultaneously. Due to the rigours of the normal working environment, over time the lugs 160 may be bent out of co-axial relationship with their member lugs 160 in each set 162.

Corresponding recesses 70 may be bent or otherwise shifted out of shape. The set 162 of tapered lugs 160 facilitates durability and extends the life of the trestle 10 using the centre frame 120.

Throughout the specification and claims the word "comprise" and its derivatives are intended to have an inclusive rather than exclusive meaning unless the contrary is expressly stated or the context requires otherwise. That is, the word "comprise" and its derivatives will be taken to indicate the inclusion of not only the listed components, steps or features that it directly references, but also other components, steps or features not specifically listed, unless the contrary is expressly stated or the context requires otherwise.

In the present specification, terms such as "apparatus", "means", "device" and

"member" may refer to singular or plural items and are terms intended to refer to a set of properties, functions or characteristics performed by one or more items or components having one or more parts. It is envisaged that where an "apparatus", "means", "device" or "member" or similar term is described as being a unitary object, then a functionally equivalent object having multiple components is considered to fall within the scope of the term, and similarly, where an "apparatus", "assembly", "means", "device" or "member" is described as having multiple components, a functionally equivalent but unitary object is also considered to fall within the scope of the term, unless the contrary is expressly stated or the context requires otherwise.

Orientational terms used in the specification and claims such as vertical, horizontal, top, bottom, upper and lower are to be interpreted as relational and are based on the premise that the component, item, article, apparatus, device or instrument will usually be considered in a particular orientation, typically with the upper bar 26 uppermost.

It will be appreciated by those skilled in the art that many modifications and variations may be made to the methods of the invention described herein without departing from the spirit and scope of the in vention.