AU2009203039A1 - Load sharing anchor for towing vehicles - Google Patents

Description

AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION Standard Patent Applicant(s): JOAN CAROLINE PENTREATH Invention Title: LOAD SHARING ANCHOR FOR TOWING VEHICLES The following statement is a full description of this invention, including the best method for performing it known to me/us: P45029AU.2 PatSetFing Application 2009-7-27.doc (M) - 2 LOAD SHARING ANCHOR FOR TOWING VEHICLES The present invention relates to a load sharing anchor for towing vehicles which in particular is used in 5 conjunction with a coupling between a towing vehicle and at towed vehicle. Trailers, caravans and other towed vehicles are connected to the driving vehicle by a coupling, usually a 10 standard ball and socket coupling. For off-road towing, or if the towed vehicle is particularly large, the ball and socket coupling can be replaced with a more heavy-duty coupling bolted to the tow hitch. 15 Particularly in off-road terrain, difficulties may be experienced with articulation between the towed and driving vehicles. Additionally, load distribution between the vehicles can vary significantly on uneven terrain or where the road underneath the respective vehicles is 20 inclined at different gradients, such as in a dip. Different road gradients between vehicles can cause sudden shifts in load which places high burdens of load on the coupling. 25 Specialist load sharing anchors have been developed for use in conjunction with standard couplings to allow load sharing capabilities between the vehicles. The specialist couplings typically constitute two weight distribution bars or load bars, acutely angled to form a 30 "V" shape. The joined ends form a vertex that is pivotally mounted on the tow hitch of a driving vehicle and is adapted to pivot around a vertical axis. The load bars generally incline downwards from the tow-hitch towards the road surface. The free ends of the load bars 35 are each provided with a chain that hooks up onto the draw bars of a caravan or trailer located above the free ends of the load bars. The chain has the effect of fixing the \\melb~f les\homeS evonnee\Keep\Speci\LOAD SHARING ANCHOR FOR TOWING VEHICLES.doc 24/02/03 - 3 vertical distance between the load bars and draw bars at at maximum thereby distributing the load of the caravan or trailer along the load bars to reduce the point load at the tow hitch. This coupling arrangement has also been 5 found to improve control of the towed vehicle. Whilst the above auxiliary coupling arrangement operates effectively on level ground, on uneven ground or hilly terrain where the driving vehicle and towed vehicle 10 are on unequal ground, and particularly in dips in the road, the maximum distance dictated by the chain may not be sufficient to accommodate the relative movement between the load bars and tow bar. This causes the chain to suffer large tensile forces which will either make the 15 chain snap or cause the load bars to deform. It is intended with the present invention to provide a load sharing anchor for towing vehicles that is capable of sharing the towing load whilst compensating for 20 independent movement between a driving vehicle and a towed vehicle. According to the present invention there is provided a load sharing anchor adapted to be connected 25 between a first vehicle in tandem with a second vehicle and allowing relative movement between first and second vehicles, the first vehicle being connected to the second vehicle through a coupling, the load sharing anchor comprising: 30 a first component attached to the first vehicle; a biasing means attached to the second vehicle and an intermediate link connecting the first component 35 and the biasing means and that allows the first component and the biasing means to be vertically separated at a maximum distance; \ \mlbfile-\home$ \von \Kep\Spei \LOAD SHARING ANCHOR FOR TOWING VEHICLES.doc ;4/02/03 wherein the biasing means ensures the first component experiences a substantially constant upward force to thereby distribute the load of the towed vehicle 5 between the two vehicles. According to the present invention there is further provided a load sharing anchor adapted to be connected between a first vehicle in tandem with a second 10 vehicle and allowing relative movement between the first and second vehicles, the first vehicle being adapted to be connected to the second vehicle through a coupling, the load sharing anchor comprising: 15 a first component attached to the first vehicle; a second component pivotally attached to the second vehicle so as to pivot about a horizontal transverse axis and in a vertical plane relative to the 20 second vehicle, wherein the first and second components are connected by an intermediate link that allows the first and second components to be vertically separated at a maximum distance; and 25 biasing means to bias the first and second components apart at the maximum distance and at a substantially constant force thereby distributing the load of the towed vehicle between the two vehicles. 30 The first and second vehicles are preferably the towing vehicle and towed vehicle respectively. The first component is preferably rigidly attached to the first vehicle but pivotable about a 35 vertical axis. The first component typically comprises forked \\melb-files\homeS\evonnee\Keep\speci\LOAD SHARING ANCHOR FOR TOWING VEHICLES.doc 24/02/03 - 5 load bars mounted at the rear of the first vehicle and substantially parallel to the road surface. Alternatively, the forked load bars may be angled 5 upwardly to a horizontal plane. The second component is preferably a right-angled lever pivotally mounted to a draw bar assembly on the second vehicle and adapted to pivot about an axis oriented 10 horizontally transverse of the second vehicle. The intermediate link is ideally a chain that defines the maximum separation distance between the load bars and lever. 15 The biasing means is preferably an air spring, and typically an air bellows, which biases against the lever to keep the link in tension and to provide a constant upward load-sharing force on the load bars. 20 Ideally, the pivoting lever compensates for variations in relative vertical travel between the first and second vehicles whilst simultaneously, owing to the biasing means, maintaining a substantially constant load 25 sharing force regardless of the amount of relative vertical travel between the vehicles. The second component is preferably also pivotable about a longitudinal axis such that differences in vehicle 30 roll between the first and second vehicles can be compensated. The forked load bars are preferably pivotally mounted on the first vehicle to pivot about a vertical 35 axis thereby allowing any variations in transverse movement between the vehicles. \\melb-files\home$\evonnee\Keep\Speci\LOAD SHARING ANCHOR FOR TOWING VEHICLES doc 24/02/03 - 6 The link ideally constitutes two separate links each attached at one end to a load bar and at the other end to a cross shaft provided transversely at the end of the lever such that links are orientated vertically above 5 the load bars to maintain a constant overall upward force on the load bars. According to the present invention there is further provided an assembly of a first vehicle and a 10 second vehicle coupled together in tandem and the above described load sharing anchor. BRIEF DESCRIPTION OF THE DRAWINGS 15 The present invention is described further by way of example with reference to the accompanying drawings by which: Figure 1 is a perspective view of a load sharing 20 anchor according to an embodiment of the present invention; Figure 2 is a side view of the anchor; 25 Figure 3 is a plan view of the anchor; Figure 4 illustrates the anchor coupled between a towing vehicle and a towed vehicle; 30 Figure 5 is a perspective view of the anchor in an extreme load sharing mode; Figure 6 is a side view of the anchor in an extreme load sharing mode; and 35 Figure 7 is a perspective view of a load sharing \\melbfil1es\home$\evonnee\Kecp\Speci\LOAD SHARING AICHOR FOR TOWING VEHICLES.doc 24/02/03 - 7 anchor according to another embodiment of the invention irt an extreme load sharing mode. DETAILED DESCRIPTION OF PREFERRED EMBODIMENT OF INVENTION 5 The present load sharing anchor is used when towing vehicles in tandem to carry a constant load between the vehicles regardless of the movement between the towing vehicle and towed vehicle or their relative angles of 10 orientation. This is achieved by the present anchor compensating for movement between the vehicles whilst maintaining a substantially constant load to ensure none of the components of the load sharing anchor are subjected to overloading forces. 15 The anchor is designed to be used in conjunction with a direct coupling which directly connects the draw bars on a towed vehicle to a tow bar, or tow hitch, on a towing vehicle. 20 The figures illustrate a load sharing anchor 10 mounted between a towing, or driving, vehicle 11 and a towed vehicle 12 such as a trailer or caravan. At the front of the draw bar assembly 13, which is defined by 25 draw bars 17, of the towed vehicle 12 is a draw bar coupling 14 which connects directly to a tow bar 15 on the rear of the towing vehicle 11. The draw bar coupling is mounted for lateral pivoting movement on the tow bar 15 to allow the towed vehicle to swing behind the towing 30 vehicle, for example when turning a corner. More particularly, the draw bar coupling is mounted to allow the vehicles freedom of relative movement in all three dimensional planes. A safety chain 16 is loosely attached between the front of the draw bar assembly 13 and rear of 35 the towing vehicle. As illustrated particularly clearly in figures 1 \\melb-files\home$\evonnee\Keep\Speci\LOAD SHARING ANCHOR FOR TOWING VEHICLES.doc 24/02/03 - 8 and 2, the load sharing anchor 10 essentially comprises two interacting structural components that are biased apart by a biasing means 20. 5 The first component 21 consists of a pair of forked load bars 22 pivotally mounted on top of the tow bar 15 and pivotable about a vertical axis to the ground. The forked load bars 22 are attached to the tow bar 15 at the fork vertex 23 from which the load bars extend 10 rearwardly and outwardly at an acute angle and along the outer sides of draw bars 17. In the embodiment shown the load bars are substantially parallel to the ground but to avoid any possibility of the bars scraping the road on uneven road surfaces the load bars are preferably mounted 15 angled upwardly to the horizontal plane. The second component 24 includes an L-shaped, or right-angled, lever 25 comprising a short arm 26 and a long arm 27. The short arm 26 is pivotally attached to 20 the draw bar assembly 13 to pivot about an axis transverse to a longitudinal direction of the tandem vehicles. As a result, lever 25 pivotally moves in a vertical plane with the unattached end 30 of long arm 27 able to move vertically above draw assembly bar 13, and specifically 25 above and between the ends 31 of forked load bars 22. To keep the load bars 22 and lever 25 separated at a maximum constant distance links 32, and more typically two chains, are connected one to each end 31 of 30 load bars 22 with the other end of each chain is attached to the ends of an elongate cross shaft 34 secured across long arm 27. The biasing means ensures the chains remain constantly taut. Elongate shaft 34 is sufficiently long to span the distance between the free ends 31 of load bars 35 22 such that the chains 32 extend vertically upwards. To also compensate for differences in relative \\melb-files\home$\evonnee\Keep\Speci\LOAD SHARING ANCHOR FOR TOWING VEHICLES.doc 24/02/03 -9 angular motion in the longitudinal direction the second component 24 is mounted on a base member 35 in the draw bar assembly 13, where the ends of the base member 35 are journalled in transverse draw bar members 36 so that the 5 base member 35, and thereby the lever 25, is pivotable about the longitudinal axis of the towed vehicle. Figure 3 illustrates clearly the members of the draw bar assembly 13. 10 In a first embodiment, the biasing means is an air spring in the form of an air bellows 20 mounted on the base member 35 in a manner to extend against an approximate centre of the short arm 26. The air spring 20 is adapted to bias against lever 25 to keep chains 32 15 constantly in tension thereby applying a substantially constant upward force on the load bars 22 and providing the load-sharing feature of the load sharing anchor. In order to maintain as much a constant force as 20 possible between lever 25 and load bars 22 the pressure in the air spring varies in reaction to the relative movement between the tandem vehicles. For example, when driving through a dip in a road as illustrated in figure 4, the first vehicle, that is the towing vehicle, reaches the 25 incline before the second vehicle at which point the two vehicles form an obtuse angle to each other and the load bars 22 at the rear of the towing vehicle form an acute angle with the drawbar assembly 13 of the towed vehicle. Figures 5 and 6 show a closer view of the load sharing 30 anchor in this mode of operation. To prevent the draw bars bending, or the chain snapping, due to an overload in vertical forces the pressure in the air spring is kept constant by decreasing the volume of air which permits the lever 25 to pivot moving long arm 27 downwardly thereby 35 compensating for the angled drop in the load bars relative to the drawbar assembly. In a similar manner the air spring compensates for any vertical force component in \\melb_files\homeSlevonnee\Keep\Speci\LOAD SHARING ANCHCR FOR TOWING VEHICLES doc 24/02/03 - 10 other movement between the vehicles such as longitudinal twist and lateral turning. Pressure in the air spring is maintained at a 5 substantially constant level by transferring air in the spring through a hose 40 to an air reservoir, such as an air cylinder (not shown) thereby reducing the volume of air in the air spring and in turn reducing the length of the spring and its force against short arm 26. When a 10 drop in the force on the chains is detected, corresponding to an upward movement of the load bars relative to the drawbar assembly, air from the air reservoir is transferred through hose 40 back into the air spring to increase the force against short arm 26 thereby causing 15 lever 25 to pivot upwards to maintain a substantially constant vertical load on the load bars 22. The pressure in the air spring/reservoir system is pre-set to produce the desired force against lever 25. The air pressure in the air spring can be manually adjusted. 20 In an alternate embodiment the air spring is not connected to a reservoir but is simply provided with a mechanical pressure relief valve that is able to be set at a desired relief pressure. To pump air back into the air 25 spring an electric air compressor is activated by an adjustable pressure limit switch to re-pressurise the air spring after partial compression due to relative movement of the load bars and draw bars. 30 For more accurate and immediate adjustment a microprocessor may be provided to monitor the loads on the load sharing anchor and compensate for the loads accordingly. 35 Alternatively, the biasing means may include hydraulics and include a hydraulic accumulator to store the fluid which passes through hydraulic lines to a \\melb-files\homcS\evonnee\Keep\Speci\LOAD SHARING AN-HOR FOR TOWING VEHICLES.doc 24/02/03 - 11 hydraulic spring. With the second component 24 of the device 10 pivotally moveable about a longitudinal axis and about a 5 transverse axis, and with the first component 21 pivotally moveable about a vertical axis, any angular movement between the towing vehicle and towed vehicle can be accommodated whilst still maintaining a substantially constant vertical force between the first and second 10 components by way of the biasing means and interconnecting chains. The load sharing anchor allows the biasing means, or air spring, to maintain a substantially constant force on the load bars without interference by relative movement between the vehicles. 15 With the present pivoting lever embodiment the ratio of displacement in the length of the air spring against the deflection at the free end 30 of long arm 27 is approximately 1:6. For example, a 20mm displacement of 20 the air spring results in a 120mm deflection at the end of the pivoting lever. A downward deflection of 120mm of the lever, and the corresponding 120mm downward deflection of ends of the load bars, is equivalent to a 1200mm rise at the rear of an average towed vehicle. Depending on the 25 dimensions of the load sharing anchor, it is conceivable that with the present anchor the rear of a towed vehicle can quite capably rise approximately 2 meters above the rear of the towing vehicle without any damage to the couplings between the vehicles. Overall, the present 30 anchor maintains a force between the two vehicles which presently only deviates about 5%. In another embodiment the air spring 20 is rotated 90' and placed directly beneath the free end 30 of 35 long lever arm 27 to extend vertically upward to compensate for any vertical movement in the anchor and maintain a constant force on the load bars. Mounting an \\melb_files\home$\evonnee\Keep\Speci\LOAD SHARING ANCHOR FOR TCWING VEHICLESdoc 24/02/03 - 12 air spring at this location would require the air spring to be larger than in the first embodiment as the displacement of the air spring would equal the distance moved by the free end 30 of long arm 27 rather than 5 operate at a ratio of 1:6 as in the first embodiment. Alternatively, the invention may do away with the lever arm arrangement and simplify the above described embodiment by providing only an upwardly extending air 10 spring on the draw bars for applying a relatively constant pressure on a cross-piece 61 on top of the air spring 20. Such an embodiment is shown in figure 7. The figure illustrates the embodiment in an extreme load sharing mode. Attached to the ends of the cross-piece 61 are 15 chains which link the cross-piece 61 to independent pivotally mounted arms 65. The arms 65 are connected to links 32 that are connected to the load bars 22. The cross-piece 61 is mounted on a short arm 67. The short arm 67 and the independent arms 65 are pivotally mounted 20 to a main cross-member 69 that houses an air receiver chamber. With this arrangement, any movement of the load bars 22 can then be directly compensated through the assembly of the cross-piece 61 and the independent arms 65 by the air spring 20. The air spring 20 operates to 25 partially deflate through an air pressure relief valve that is pre-set to exhaust at a given pressure. An electric air compressor re-pressurises the spring in order to maintain a substantially constant upward force on the load bars. 30 Other mechanically equivalent embodiments of the second component 24 on the load sharing anchor 10 and of the biasing means 20 are possible within the scope of the present device provided the end effect achieves a constant 35 load-sharing upward force on the load bars regardless of any movement between the towing and towed vehicles. \\melb_fIles\home$\evonneC\Keep\Speci\LOAD SHARING ANCHOR FOR TOWING VEHICLES.coc 24,'02/03 - 13 The load sharing anchor allows full articulation between vehicles connected in tandem and eliminates overload forces on load bars, particularly in off-road conditions, by allowing for the downward displacement of 5 the load bars. The present anchor also ensures a significant load distribution from the direct coupling and maintains this load regardless of the driving conditions and without damage to the direct couplings or the anchor itself. In practical terms this means that the vehicles 10 in tandem are capable of moving independently whilst providing a secure and dependable coupling therebetween. It will be understood to persons skilled in the art of the invention that many modifications may be made without departing from the spirit and scope of the invention. 15 \\melb-files\homeS\evonnee\Keep\Speci\LOAD SHARING ANCHOR FOR TOWING VEHICLES.doc 24/02/03

Claims (15)

1. A load sharing anchor adapted to be connected 5 between a first vehicle in tandem with a second vehicle and allowing relative movement between the first and second vehicles, the first vehicle being adapted to be connected to the second vehicle through a coupling, the load sharing anchor comprising: 10 a first component attached to the first vehicle; a second component pivotally attached to the second vehicle so as to pivot about a horizontal 15 transverse axis and in a vertical plane relative to the second vehicle, wherein the first and second components are connected by an intermediate link that allows the first and second components to be separated at a maximum distance; and 20 biasing means to bias the first and second components apart at the maximum distance and at a substantially constant force thereby distributing the load of the towed vehicle between the two vehicles. 25

2. The anchor defined in claim 1 wherein the first and second vehicles are a towing vehicle and a towed vehicle respectively. 30

3. The anchor defined in claim 1 or claim 2 wherein the first component is rigidly attached to the first vehicle but pivotable about a vertical axis.

4. The anchor defined in any one of the preceding 35 claims wherein the first component comprises a pair of forked load bars mounted at the rear of the first vehicle and substantially parallel to the road surface. \\melb-files\home$\evonnee\Keep\Speci\LOAD SHARING ANCHOR FOR TOWING VEHICLES.doc 24/02/03 - 15 5. The anchor defined in claim 4 wherein the forked load bars are angled upwardly to a horizontal plane.

5

6. The anchor defined in any one of the preceding claims wherein the second component is a right-angled lever pivotally mounted to a draw bar assembly on the second vehicle and adapted to pivot about an axis oriented horizontally transverse of the second vehicle. 10

7. The anchor defined in any one of the preceding claims wherein the intermediate link is a chain that defines the maximum separation distance between the load bars and lever. 15

8. The anchor defined in any one of the preceding claims wherein the biasing means is an air spring which biases against the second component to keep the intermediate link in tension and to provide a constant 20 upward load-sharing force on the load bars.

9. The anchor defined in any one of the preceding claims wherein the pivoting second component compensates for variations in relative vertical travel between the 25 first and second vehicles whilst simultaneously, owing to the biasing means, maintaining a substantially constant load-sharing force regardless of the amount of relative vertical travel between the vehicles. 30

10. The anchor defined in any one of the preceding claims wherein the second component is also pivotable about a longitudinal axis such that differences in vehicle roll between the first and second vehicles can be compensated. 35

11. The anchor defined in any one of the preceding claims wherein the forked load bars are pivotally mounted \\melbftiles\home$\evonnee\Keep\Speci\LOAD SHARING ANCHOR FOR TOWING VEHICLES.doc 24102/03 - 16 on the first vehicle to pivot about a vertical axis thereby allowing any variations in transverse movement between the vehicles. 5

12. The anchor defined in any one of the preceding claims wherein the intermediate link constitutes two separate links each attached at one end to a load bar and at the other end to the second component such that links are orientated above the load bars to maintain a constant 10 overall upward force on the load bars.

13. A load sharing anchor adapted to be connected between a first vehicle in tandem with a second vehicle and allowing relative movement between first and second 15 vehicles, the first vehicle being connected to the second vehicle through a coupling, the load sharing anchor comprising: a first component attached to the first vehicle; 20 a biasing means attached to the second vehicle and an intermediate link connecting the first component and the biasing means and that allows the first component and the biasing means to be separated at a maximum 25 distance; wherein the biasing means ensures the first component experiences a substantially constant upward force to thereby distribute the load of the towed vehicle 30 between the two vehicles.

14. An assembly of a first vehicle and a second vehicle coupled together in tandem and the load sharing anchor defined in any one of the preceding claims mounted 35 to the vehicles. \\mlbbfiles\homeS\evene\Keep\Speci\LOAD SHARING ANCHC-R FOR TOWING VEHICLES.doc 24/02/03 - 17

15. A load sharing anchor substantially as hereinbefore described with reference to the accompanying drawings. 5 10 \\mel bfiles\home$\evonnee\Keep\Speci\LOAD SHARING ANCHrR FOR TOWING VEHICLES.doc 24/02/03