AU2010201760A1 - Pivoting Draw Bar - Google Patents

Description

P/00/011 28/5/91 Regulation 3.2 AUSTRALIA Patents Act 1990 ORIGINAL COMPLETE SPECIFICATION STANDARD PATENT Name of Applicant: Roadwest Transport Equipment & Sales Pty Ltd Actual Inventors: Paul Lavall Paul Rivers Address for service is: Goija Haines & Friend 35 Wickham Street East Perth Western Australia 6004 Attorney Code: Invention Title: Pivoting Draw Bar The following statement is a full description of this invention, including the best method of performing it known to me: 1 Pivoting Draw Bar Field of the Invention This invention relates to the transport industry and to a connector for connecting a trailer to a towing vehicle. In particular this invention relates to a drawbar to be fitted 5 to a trailer, which is used to connect the trailer to a towing vehicle. Background Art The following discussion of the background art is intended to facilitate an understanding of the present invention only. It should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred 10 to was part of the common general knowledge as at the priority date of the application. Draw bars which a fitted to trailers have for simplicity, been made of rolled hollow section (RHS) mild steel, pieces of which are laid out in an A-frame configuration and welded. The apex of the A-frame has a hitch connector in the form of a tow eye 15 which in use is connected to a tow hitch mounted to the rear of a like trailer or truck body. RingfederTM tow hitches are a typical example of tow hitches used in this manner in the transport industry. The opposite end of the A-frame is connected to the leading axle or bogey of the trailer, the connection being a pivotal connection about a horizontal transverse axis, 20 to allow vertical arcuate movement of the draw bar, as the truck trailer combination negotiates varying slopes and undulations in the road or other ground being negotiated. Draw bars of this type suffer from a number of disadvantages, which the applicant has sought to overcome. It is an object of this invention to provide a draw bar which 25 at least provides an alternative to draw bars of the type described above. Throughout the specification unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers. 2 Throughout the specification unless the context requires otherwise, the word "include" or variations such as "includes" or "including", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers. 5 Disclosure of the Invention In accordance with one aspect of the present invention there is provided a draw bar for pivotal connection to the leading axle or bogey of a trailer, about a horizontal transverse axis to allow vertical arcuate movement of the draw bar, said draw bar having a pair of diverging arms provided at their diverged extremity with mounting 10 members about which the pivotal connection is made, and extending away from their confluence in a longitudinal bar portion lying substantially along the same longitudinal axis of said diverging arms, the end of said longitudinal bar portion being provided with a hitch connector for connection to a tow hitch mounted to the rear of a like trailer or truck body, said longitudinal bar portion extending for a distance of at least 15 30% of the transverse width of the vehicle. Preferably said longitudinal bar portion comprises a fully enclosed tubular section save for any apertures for egress of services. Any services will include electric cabling, hydraulic and pneumatic lines. Preferably any said apertures are located facing downward and/or rearward. In this manner debris are unlikely to build up 20 inside the tubular section of said longitudinal bar portion. Preferably said divergent arms each comprise a channel section having a longitudinal opening. Preferably the longitudinal openings face each other. Preferably said longitudinal bar portion extends for a distance of at least 40% of the transverse width of the vehicle. 25 Preferably said longitudinal bar portion extends for a distance of at least 45% of the transverse width of the vehicle. Preferably said longitudinal bar portion extends for a distance of at least 50% of the transverse width of the vehicle. Preferably said pair of diverging arms forms a triangular frame, the base of the 30 triangular frame being provided with said mounting members, and the apex of the triangular frame continuing in said longitudinal bar portion. 3 Preferably said longitudinal bar portion has a top portion provided with sloping surfaces meeting in a longitudinally extending peak, to facilitate shedding of material spilt on said draw bar. Preferably said draw bar is fabricated from portions of flat plate pressed to form the 5 required shapes, and fully welded, preferably using full penetration but welds. It is most preferred that the portions comprise two portions, preferably being an upper half and a lower half. Preferably said draw bar is fabricated using tabbed construction for positional registration of portions prior to welding. This obviates the need to assemble the 10 portions in a jig. Preferably said longitudinal bar portion includes an entry aperture on the underside of a forward portion thereof for receiving services for routing through said draw bar to reach the trailer. Brief Description of the Drawings 15 A preferred embodiment of the invention will now be described in the following description made with reference to the drawings, in which: Figure 1 is an isometric view from above of a pivoting draw bar according to the embodiment; Figure la is a further isometric view from above of the pivoting draw bar 20 according to the embodiment; Figure 2 is an isometric view from below of the pivoting draw bar according to the embodiment; Figure 3 is a plan view from above of the pivoting draw bar according to the embodiment; 25 Figure 4 is a rear plan view of the pivoting draw bar according to the embodiment; Figure 5 is a side plan view of the pivoting draw bar according to the embodiment; and Figure 6 is an isometric view from below showing the pivoting draw bar 30 according to the embodiment in use. 4 Best Mode(s) for Carrying Out the Invention The following description refers generally to figure 1, except where noted. The embodiment is a pivoting draw bar 11 for pivotal connection to the leading axle 13 or bogey of the trailer 14, about a horizontal transverse axis 15 to allow vertical arcuate 5 movement of the draw bar 11 about the horizontal transverse axis 15. The draw bar 11 has a pair of diverging arms 17, 19 provided at their diverged extremity 21 with mounting members in the form of vertically disposed plate members 23 forming an outer pivot clevis 25 and an inner pivot clevis 27 about which the pivotal connection is made. Located along the horizontal transverse axis 15 in each plate member 23 is 10 an aperture 29 (shown in figure 1a) in which are received a pivot eye bush kit 31 (one pivot eye bush kit 31 at the end of each diverging arm 17, 19, best seen in figures 2 and 3). Extending away from the confluence 33 of the diverging arms 17, 19 (i.e., where the diverging arms join) is a longitudinal bar portion 35 which has a forward end 37 15 located away from the confluence 33. The longitudinal bar portion 35 lies substantially along the same longitudinal axis of the diverging arms 17, 19, and in the same horizontal plane (note that "horizontal plane" is used in a relative sense, and assumes that the draw bar 11 is not tilted out of the horizontal plane about the horizontal transverse axis 15). 20 The diverging arms 17, 19 are joined by a rear transverse strut 39. The rear transverse strut 39 is formed by an upper plate member 41 and a lower plate member 43 reinforced with a rear bulkhead 45 (see figs 2, 3 and 4) and gussets 47 (shown in hidden detail in fig 1a). The diverging arms 17, 19 and the rear transverse strut 39 form a triangular frame. Further reinforcing is provided by an additional transverse 25 strut 49 formed by an upper plate member 51 and a lower plate member 53 (best seen in figure 2) reinforced with a bulkhead 55 (shown in hidden detail in fig 1a). An additional bulkhead 57 (shown in hidden detail in fig 1a) is located at the confluence 33 of the diverging arms 17, 19, where the longitudinal bar portion 35 is joined. The bulkheads 45, 55, and 57 are provided with apertures for the routing of services 59 30 (see fig 1a), such as electrical cabling, and hydraulic and pneumatic lines. The diverging arms 17, 19 are formed from an upper half 17a, 19a, and a lower half 17b, 19b, and the confluence 33 thereof also comprises an upper half 33a and a lower half 33b. The upper halves 17a 19a 33a, and the upper plate members 41 and 51 are of unitary construction being formed from a single sheet of flat plate, cut out 5 using a CNC plasma cutter, and folded in a CNC press. The lower halves 17b 19b 33b and lower plate members 43 and 53 are also of unitary construction being formed from a single sheet of flat plate, cut out using a CNC plasma cutter, and folded in a CNC press. The longitudinal bar portion 35 also comprises upper and 5 lower halves formed in the same manner. The upper halves of these components have upper surfaces sloped at 78 degrees to the vertical, the sloped upper surfaces meeting at an apex 61 located along the central longitudinal extent of the draw bar 11. The upper and lower halves of these parts are joined together both longitudinally and at the confluence 33 by full penetration butt welds 62. The bulkheads 45, 55, 10 and 57 are secured using fillet welds. All of the sheet material forming these parts is quench tempered steel plate sold under the trade mark DOMEX 700. Most plate utilised in the construction described above is of 5mm thickness, except for the bulkheads 45 and 55 which are of 8mm plate, the gussets 47 which are of 10mm plate and the pivot clevises 25 and 27 which are of 12mm plate. 15 The forward end of the longitudinal bar portion 35 has a tow eye 63 secured thereto by welding into support plates 64 and 65, which are in turn welded to the forward end of the longitudinal bar portion 35. A cover portion 67 having like sloped upper surfaces as the upper portions is provided to cover the top of the support plates 63 and 65. The cover portion 67 prevents ingress of particulate matter during unloading 20 of rear tipping bodies, which the draw bar 11 is intended to be used with. The sloped upper surfaces of the cover portion 67, the longitudinal bar portion 35, and the upper halves 17a 19a 33a, and the upper plate members 41 and 51 assists in shedding of any particulate matter that may rest on top after completion of a tipping operation. Particulate matter will be shed as the truck/trailer moves off, assisted by road 25 vibration. It is desirable to shed such material which could otherwise be dislodged at high speed on the open highway, providing a hazard for other road users. Referring to figure 2, located on the underside of the forward end 37 of the longitudinal bar portion 35 is an elongate aperture 69 through which services 59 connected to the towing vehicle are routed. In this manner the draw bar 11 provides 30 an enclosed protective cover for the services 59, which might otherwise be exposed to particulate matter during tipping, or that which could be flicked up while driving on the open road. Also located on the underside of the draw bar 11, proximal to the confluence, is a support leg pivot bracket 71 and striker plate 73. Referring to figure 6, the trailer 14 attached to a tipping prime mover 83 by the draw 35 bar 11 according to the embodiment is shown. The longitudinal bar portion 35 length 6 is selected so that it extends the confluence 33 position to a length which is about half of the transverse width of the vehicle. In this manner, the tipping prime mover 83 (or trailer and prime mover with a fifth wheel, as the case may be), may be reversed to jack-knife the combination of towed trailer 81 and tipping prime mover 83 to a full 5 90 degrees to allow the lead tipper to tip over the draw bar 11 as shown in figure 6. The ability to do this also contributes to minimising particulate material that might fall onto the draw bar. The prior art A-frame draw bar which is constructed of mild steel RHS is unable to fully jack knife to the extent that the drawbar of the invention and embodiment can, 10 and so will always collect particulate material that falls onto it. Furthermore, if a driver attempts to jack knife with such a prior art A-frame, and the vehicle collides with the side edge of the prior art A-frame, irreparable damage will be done to the structure of the prior art A-frame. In comparison, being formed of quench tempered plate, there is some resilience in the drawbar of the invention and embodiment, and it can withstand 15 such a collision to a far greater extent. Finally, the drawbar of the invention and embodiment is some 15% lighter than a prior art A-frame draw bar which is constructed of mild steel RHS. This weight saving translates to savings in fuel costs. It will be appreciated that the manner of construction of the divergent arms forms a 20 channel section of each divergent arm, each having a longitudinal opening, where the longitudinal openings face each other. While the joins that are welded are shown as straight lines, when the parts are cut out, they are so formed with tabs that fit together in interlocking fashion. This technique provides positional registration of portions prior to welding, and obviates 25 the need to assemble the portions in a jig. It should be appreciated that the invention is not limited to the particular embodiment described herein, and that changes may be made to the embodiment without departing from the spirit and scope of the invention. 7

Claims (14)

1. A draw bar for pivotal connection to the leading axle or bogey of a trailer, about a horizontal transverse axis to allow vertical arcuate movement of the draw bar, said draw bar having a pair of diverging arms provided at their diverged 5 extremity with mounting members about which the pivotal connection is made, and extending away from their confluence in a longitudinal bar portion lying substantially along the same longitudinal axis of said diverging arms, the end of said longitudinal bar portion being provided with a hitch connector for connection to a tow hitch mounted to the rear of a like trailer or truck body, said 10 longitudinal bar portion extending for a distance of at least 30% of the transverse width of the vehicle.

2. A draw bar as claimed in claim 1 wherein said longitudinal bar portion comprises a fully enclosed tubular section save for any apertures for egress of services. 15

3. A draw bar as claimed in claim 2 wherein any said apertures are located facing downward and/or rearward.

4. A draw bar as claimed in any one of the preceding claims wherein said divergent arms each comprise a channel section having a longitudinal opening.

5. A draw bar as claimed in claim 5 wherein the longitudinal openings face each 20 other.

6. A draw bar as claimed in any one of the preceding claims wherein said longitudinal bar portion extends for a distance of at least 40% of the transverse width of the vehicle.

7. A draw bar as claimed in claim 6 wherein said longitudinal bar portion extends 25 for a distance of at least 45% of the transverse width of the vehicle.

8. A draw bar as claimed in claim 6 wherein said longitudinal bar portion extends for a distance of at least 50% of the transverse width of the vehicle.

9. A draw bar as claimed in any one of the preceding claims wherein said pair of diverging arms forms a triangular frame, the base of the triangular frame being 30 provided with said mounting members, and the apex of the triangular frame continuing in said longitudinal bar portion. 8

10. A draw bar as claimed in any one of the preceding claims wherein said longitudinal bar portion has a top portion provided with sloping surfaces meeting in a longitudinally extending peak, to facilitate shedding of material spilt on said draw bar. 5

11. A draw bar as claimed in any one of the preceding claims wherein said draw bar is fabricated from portions of flat plate pressed to form the required shapes, and fully welded, preferably using full penetration but welds.

12. A draw bar as claimed in claim 11 wherein the portions comprise two portions, being an upper half portion and a lower half portion. 10

13. A draw bar as claimed in claim 11 or 12 wherein said draw bar is fabricated using tabbed construction for positional registration of portions prior to welding.

14. A draw bar as claimed in any one of the preceding claims wherein said longitudinal bar portion includes an entry aperture on the underside of a forward portion thereof for receiving services for routing through said draw bar to reach 15 the trailer. 9