P/00/012 Regulation 3.2 AUSTRALIA Patents Act 1990 ORIGINAL COMPLETE SPECIFICATION INNOVATION PATENT Invention Title: "HEAVY LOAD TRAILER" The following statement is a full description of this invention, including the best method of performing it known to me/us: 1 TITLE HEAVY LOAD TRAILER FIELD OF THE INVENTION 5 This invention relates generally to trailers for use in the trucking industry. More particularly, this invention relates to heavy load trailers having steerable axles. BACKGROUND TO THE INVENTION 10 The commercial trucking industry includes a wide variety of heavy duty trailers for use in hauling oversized and heavy loads. In some circumstances the ability to haul such loads over long distances using a single prime mover can be critical for enabling the trucking industry to be economically viable. 15 Trailers are often attached directly to a prime mover, or may be attached to another trailer in a road train configuration. Common configurations of trailer axles include three-axle bogeys having four tires on each axle. Long haul transport vehicles often include B-doubles with two trailers that each have three axles. Further, some jurisdictions authorise the 20 use of B-triple trucks and even four trailer road trains. Although economically efficient, long and heavy commercial vehicles sometimes can be very difficult to manoeuvre, or even dangerous to manoeuvre, on crowded public roads. To improve manoeuvrability, trailers are often outfitted with steerable axles that enable trailers to better track the 25 path of the prime mover. Thus cornering ability and the ability to adhere to a single road lane can be improved. Various combinations of steerable and non-steerable axles have been used. However, such combinations often do not optimise manoeuvrability, safety and load carrying capacity, whilst also complying with bridge formulas 30 for heavy vehicles as published by various jurisdictions and regulatory bodies. Therefore, there is a need for an improved heavy load trailer design.
2 OBJECT OF THE INVENTION An object of the invention is to overcome or at least alleviate one or more of the above problems and/or provide the consumer with a useful or 5 commercial choice. SUMMARY OF THE INVENTION In one form, although it need not be the only or indeed the broadest form, the invention resides in a heavy load trailer, comprising: 10 a front steerable axle; a rear steerable axle positioned rearward of the front steerable axle; a non-steerable axle set positioned between the front steerable axle and the rear steerable axle; and a frame supported by the front steerable axle, the rear steerable axle, 15 and the non-steerable axle set. Optionally, the non-steerable axle set comprises two axles. Optionally, the non-steerable axle set comprises three axles. Optionally, four wheels are mounted to each axle. Optionally, the non-steerable axle set comprises a load sharing 20 suspension. Optionally, the steerable axles comprise load sharing suspensions. Further features of the present invention will become apparent from the following detailed description. Throughout this specification, unless the context requires otherwise, 25 the words "comprise", "comprises" and "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. BRIEF DESCRIPTION OF FIGURES 30 In order that the invention may be readily understood and put into practical effect, preferred embodiments will now be described by way of example with reference to the drawings as follows: 3 FIG. 1 is a diagram illustrating a side view of two heavy load trailers, according to an embodiment of the present invention. FIG. 2 is a diagram illustrating an underside view of the heavy load trailers of FIG. 1. 5 FIG. 3 is a diagram illustrating exemplary longitudinal dimensions of one of the trailers of FIG. 1, according to an embodiment of the present invention. FIG. 4 is a diagram illustrating a side view of a heavy load trailer according to an alternative embodiment of the present invention. 10 DETAILED DESCRIPTION OF THE INVENTION The present invention has been devised, at least in part, to provide an improved heavy load trailer. Referring to FIG. 1, a diagram illustrates a side view of heavy load trailers 100, 145, according to an embodiment of the 15 present invention. The trailer 100 includes a load, such as a gas tank 105, which is supported by a frame 110. The frame 110 is supported by a front steerable axle 115, a rear steerable axle 120 positioned rearward of the front steerable axle 115, and a non-steerable axle set 125 positioned between the front steerable axle 115 and the rear steerable axle 120. A twin axle dolly 20 130 is positioned at a front of the trailer 100 and includes a drawbar 135. The drawbar 135 is connected to a tow hitch 140 at a rear of the second heavy load trailer 145. Tyres 150 are then connected to the various wheels of the trailers 100, 145. The trailer 100 thus provides a platform for transporting a long and/or 25 heavy load, while providing improved manoeuvrability, safety and load carrying capacity. Using a load sharing suspension, the non-steerable axle set 125 can carry more weight than either the front steerable axle 115 or the rear steerable axle 120. During forward operation on a road, that causes the tyres 150 of the non-steerable axle set 125 to seek a straight path that is less 30 subject to turning forces induced by the front steerable axle 115 and/or the rear steerable axle 120. Therefore the combination of the front steerable axle 115, the non-steerable axle set 125, and the rear steerable axle 120 4 produces a very stable and yet highly manoeuvrable trailer operation. Referring to FIG. 2, a diagram illustrates an underside view of the heavy load trailers 100, 145. As shown, four wheels are mounted to each axle 200 in the non steerable axle set 125, and to the front steerable axle 5 115 and the rear steerable axle 120. Those having ordinary skill in the art will appreciate that, according to alternative embodiments, more wheels or fewer wheels may be attached to the various axles 115, 120, 200. In this specification an axle generally refers to a fixed axle beam and its various components including brakes. A steerable axle generally refers to a 10 steerable or self-tracking axle beam and its various components including brakes. Further, an axle set may include one or more axles. A load sharing suspension (not shown) is used to mount the frame 110 to the various axles 115, 120, 200. For example, as defined in Australian Vehicle Standards Rules (AVSR) Rule 65, a load sharing 15 suspension may mean "an axle group suspension system that: (a) is built to divide the load between the tyres on the group so that no tyre carries a mass over 10% more than the mass that it would carry if the load were divided equally; and (b) has effective damping characteristics on all axles of the group." Various types of load sharing suspensions can be used, such as 20 airbag suspension models AO/D30k or AM/D30 supplied by BPW Transpec Pty Ltd, or equivalents. As known by those having ordinary skill in the art, load sharing is generally achieved by inter-connecting air lines between various air bags of the various suspensions. Ride height can be maintained via height control valves plumbed into the air lines of the suspension system. 25 Typical suspensions include one or more suspension mediums and their components acting solo or in concert with each other and assembled to form one complete suspension per axle assembly. The present invention may employ, but is not limited to, a suspension combining an air bag and a trailing arm. 30 Also, various types of self steering axles, such as the LL self steering axle or model SMZFHLL10110 ECO PLUS self tracking axle supplied by BPW Transpec Pty Ltd or equivalents, can be used in accordance with 5 embodiments of the present invention. As known by those having ordinary skill in the art, self steering axles can reduce total rolling resistance through bends, reduce stress on a superstructure, and increase overall trailer service life. 5 For purposes of providing an example only, a typical length of the trailer 100 is 14 metres, with the dolly 130 supporting 17 tonnes and the combination of the front steerable axle 115, the non-steerable axle set 125, and the rear steerable axle 120 supporting 35 tonnes. The tyres 150, for example, may be size 8.25R15 or larger. 10 Referring to FIG. 3, a diagram illustrates exemplary longitudinal dimensions of the trailer 100, according to an embodiment of the present invention. For example, consider that the front steerable axle 115 carries a load of seven tonnes, the non-steerable axle set 125 carries a load of 21 tonnes, and the rear steerable axle 120 carries a load of seven tonnes. The 15 following relative dimensions may then be appropriate: L = 7.5 metres; M = 5 metres; N = 5 metres; 0 = 2.5 metres; 20 P =2.5 metres; Q = 2.5 metres; and R = 1.25 metres. Referring to FIG. 4, a diagram illustrates a side view of a heavy load trailer 400, according to an alternative embodiment of the present invention. 25 The trailer 400 includes a load, such as a gas tank 405, which is supported by a frame 410. The frame 410 is supported by a front steerable axle 415, a rear steerable axle 420 positioned rearward of the front steerable axle 415, and a non-steerable axle set 425 positioned between the front steerable axle 415 and the rear steerable axle 420. A "fifth wheel coupling" 430 is 30 positioned at a front of the trailer 400. The fifth wheel coupling 430 connects to a rear turn-table of a prime mover 435. Tyres 440 are connected to the various wheels of the trailer 400 and prime mover 435.
6 Exemplary longitudinal dimensions in millimetres of the heavy load trailer 400 and prime mover 435 are provided in a lower portion of FIG. 4. Those having ordinary skill in the art will appreciate that various other alternative embodiments of the present invention are enabled by the present 5 disclosure. For example, various alternative types of loads, such as box trailers and flat bed loads, may be used in conjunction with the present invention. Further, a non-steerable axle set may include various numbers of axles, such as the tri-axle arrangements shown in the non-steerable axle sets 125, 425, or quad, dual or single axle arrangements. 10 Embodiments of the present invention thus can provide numerous advantages, including: 1) improved manoeuvrability; 2) improved safety; 3) lower carbon emissions and reduced environmental impact, as fewer trucks are required to perform transport tasks; 4) reduced damage to road infrastructure, as steerable axles produce less scuffing of road surfaces; 5) 15 reduced road congestion; and 6) reduced fuel consumption. In this patent specification, adjectives such as first and second, front and rear, etc., are used solely to define one element or method step from another element or method step without necessarily requiring a specific relative position or sequence that is described by the adjectives. Words such 20 as "comprises" or "includes" are not used to define an exclusive set of elements or method steps. Rather, such words merely define a minimum set of elements or method steps included in a particular embodiment of the present invention. The above description of various embodiments of the present 25 invention is provided for purposes of description to one of ordinary skill in the related art. It is not intended to be exhaustive or to limit the invention to a single disclosed embodiment. As mentioned above, numerous alternatives and variations to the present invention will be apparent to those skilled in the art of the above teaching. Accordingly, while some alternative embodiments 30 have been discussed specifically, other embodiments will be apparent or relatively easily developed by those of ordinary skill in the art. Accordingly, this patent specification is intended to embrace all alternatives, modifications 7 and variations of the present invention that have been discussed herein, and other embodiments that fall within the spirit and scope of the above described invention. Limitations in the claims should be interpreted broadly based on the 5 language used in the claims, and such limitations should not be limited to specific examples described herein. In this specification, the terminology ''present invention" is used as a reference to one or more aspects within the present disclosure. The terminology "present invention" should not be improperly interpreted as an identification of critical elements, should not be 10 improperly interpreted as applying to all aspects and embodiments, and should not be improperly interpreted as limiting the scope of the claims.