AU763140B2

AU763140B2 - A towbar assembly

Info

Publication number: AU763140B2
Application number: AU34042/00A
Authority: AU
Inventors: Allan James Bartlett; Geoffrey Norman Bartlett
Original assignee: BARTLETT TRANSP IMPROVEMENTS P
Current assignee: BARTLETT TRANSPORT IMPROVEMENTS PTY Ltd
Priority date: 1999-05-12
Filing date: 2000-05-11
Publication date: 2003-07-17
Anticipated expiration: 2020-05-11
Also published as: AU3404200A

Description

I) 4i Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

(ORIGINAL)

Name of Applicant: Actual Inventor(s): Bartlett Transport Improvements Pty Ltd 004 613 923) BARTLETT, Geoffrey Norman BARTLETT, Allan James DAVIES COLLISON CAVE, Patent Attorneys, 1 Little Collins Street, Melbourne, Victoria 3000.

"A Towbar Assembly" Address for Service: Invention Title: Details of Associated Provisional Application No: PQ0303/99 The following statement is a full description of this invention, including the best method of performing it known to me/us: P:\OPER\SSB\TQWBAR.SPE 11/5/00 -2- A TOWBAR ASSEMBLY FIELD OF THE INVENTION The present invention relates to towbars and, more particularly, to heavy duty towbars for heavy vehicles. Generally, a towbar is a structure attached to the rear of a towing vehicle as a means of mounting a tow coupling assembly. A component of the tow coupling assembly S. :is connected to a vehicle to be towed, which may be a trailer, for example.

.e BACKGROUND OF THE INVENTION It is generally held to be desirable for Australian manufacturers of equipment and materials S"to design their products to conform with Australian Standards and Australian Design Rules, S"and manufacturers generally appear to experience a good degree of success in those conforming product lines. The present invention has been designed with Australian Design Rule 62/01 "Mechanical Connections Between Vehicles" in mind.

When manufacturing a towbar for trucks or other heavy duty purposes, it is commonly desirable to use a square hollow steel crossmember, which forms the upper part of a popular type of towbar, between the longitudinal members of the vehicle's chassis substantially towards the rear of the vehicle. However, the square hollow sections which are available from the steel mills in suitable dimensions (to fit a large vehicle) have a maximum wall thickness of 9 mm. For the grade of steel used in these sections, 9 mm is insufficient to meet the strength requirements of the Rule 62/01, which at maximum trailer ratings necessitates a wall thickness of 16 mm for the same grade of steel.

SUMMARY OF THE INVENTION The present invention provides a towbar assembly including a towbar beam and a tow coupling assembly connected to the towbar beam for forming a tow coupling between first and second vehicles, the towbar beam being formed from first and second L-shaped elongate P:\OPER\SSB\TOWBAR.SPE 1/5/00 -3members, the first member having first and second legs and the second member having third and fourth legs, said first and second members being juxtaposed to one another and joined to make a hollow beam of generally rectangular section with the first leg being generally parallel to the third leg and the second leg being generally parallel to the fourth leg, wherein at least a part of the first leg is longer than the third leg to thereby define an apron to which the tow coupling assembly is connected.

Preferably, the apron has a lesser width than the distance between opposing ends of the first member. Preferably, the part of the first member having the apron is generally T-shaped, with 10 the apron forming the bottom of the T-shape.

o..oo Preferably, the towbar assembly includes chassis end plates connected to the towbar beam at opposing ends thereof for connecting the towbar assembly to the chassis of the first vehicle.

Preferably, said first and second members are joined by welding, preferably using fillet welds. Preferably, the members are made of steel. Preferably, the tow coupling assembly °includes a ball assembly. Preferably, the towbar assembly includes a lower crossmember interconnecting the apron and the ball assembly. Alternatively, the tow coupling assembly includes a pin coupling assembly. Preferably, the pin coupling assembly is removably connected to the apron. Alternatively, the tow coupling assembly may include a hook coupling or other type of coupling. Preferably, the first and second members are initially flat and are formed in an L-shape by use of a brake press. Preferably, stiffening plates join the second member with the lower crossmember. Preferably, dropper plates are fixed to the first member, second member and a lower crossmember in order to further enhance the rigidity of the towbar assembly. Preferably, the first leg has at least two safety chain attachments joined thereto for releasably attaching safety chains connected to the vehicle to be towed.

Preferably, the thickness of at least the first member and the second member is about 16 mm to accommodate trailing vehicle loads of up to approximately 30 tonnes. Alternatively, the thickness of at least the first member and the second member is about 12 mm to accommodate trailing vehicle loads of up to approximately 10 tonnes.

P:\OPER\SSB\TOWBAR.SPE 11/5/00 -4- The present invention also provides a towbar beam including first and second L-shaped elongate members, the first member having first and second legs and the second member having third and fourth legs, said first and second members being joinable in juxtaposition to one another to make a hollow beam of generally rectangular section with the first leg being generally parallel to the third leg and the second leg being generally parallel to the fourth leg, wherein at least a part of the first leg is longer than the third leg to thereby define an apron for connecting thereto a tow coupling assembly.

.o Advantageously, the structure of the towbar beam provides a towbar assembly of sufficient strength and structural integrity to meet the requirements of Australian Design Rule 62/01.

Preferred embodiments of the present invention are described in detail, and by way of example only, with reference to the accompanying drawings.

BRIEF DESCRIPTION OF TILE DRAWINGS Figure 1 is an exploded view of a towbar assembly in accordance with a first embodiment of the present invention; Figure 2 is a perspective view of the towbar assembly; Figure 3 is a cross-sectional view of the towbar assembly; Figure 4 is an end view of the towbar assembly; Figure 5 is a top view of the towbar assembly; Figure 6 is a front view of the towbar assembly; Figure 7 is an exploded view of a towbar assembly in accordance with a second embodiment of the present invention; Figure 8 is a perspective view of the towbar assembly of the second embodiment; Figure 9 is a cross-sectional view of the towbar assembly of the second embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Any dimensions shown on the accompanying drawings are not intended to be limiting and are P:\OPER\SSB\TOWBARSPE 11/5/00 merely to indicate an approximate scale or frame of reference to the skilled addressee.

Referring to Figures 1 to 6, it can be seen that the towbar assembly 20 is made up of a number of components. The assembly 20 includes an inner angle 1 and an outer angle/apron 2 which are welded together and form the basic structural member for connecting a tow coupling assembly 10 to a vehicle's chassis. Chassis end plates 3 are welded on to the inner angle 1 and outer angle/apron 2 and the assembly can then be bolted on to the chassis through the chassis end plates 3. The tow coupling assembly 10 is attached to a lower crossmember 6 which is welded to the outer angle/apron 2 This weld attachment is then reinforced by attaching stiffeners 5 and dropper plates 4 so as to achieve a strong, rigid structure. The welds 15 between the inner angle 1, outer angle/apron 2, stiffeners 5 and lower crossmember 6 are shown in cross-section in Figure 3, although the welds of the dropper plates 4 and end chassis plates 3 are not shown.

The outer angle/apron 2 has an apron area in the shape of a tongue which is of a lesser width than the width of the chassis. The width of the tongue-shaped area of the outer angle/apron 2, as shown in Figure 6, is approximately half (or less) of the total width of the towbar assembly 20 or 30, although the proportions may be varied according to the width of the i vehicle chassis or other fitting parameters. The outer angle/apron 2, when in use, extends downward from the chassis to hold the attached tow coupling assembly 10 at a height which is more suitable for coupling to the corresponding coupling of a vehicle to be towed. The apron 2 may be made to extend downward to a greater or lesser degree than that shown in the drawings, depending on the dimensions of the vehicle chassis or the relative height of the corresponding coupling on the vehicle to be towed. The form of the outer angle/apron 2 provides a rigid structure having the desired strength to meet the requirements of Design Rule 62/01 while not being unduly heavy.

The safety chain attachments 7 are for attaching safety chains between the towed vehicle and the towing vehicle to maintain the attachment of the two vehicles in the event that the coupling assembly fails. The safety chain attachments 7 are welded on to the apron 2.

P:\OPER\SSB\TOWBAR.SPE- 1 /5/00 -6- The outer angle/apron 2 can be adapted to fit a variety of tow coupling assemblies, an example of which can be seen in Figures 7 to 9. In Figure 7, the outer angle/apron 2' has an opening for attaching to it an automatic pin coupling assembly 10'. In this embodiment, the lower crossmember 6 is replaced by a lower pressed angle crossmember 6' which is used to stiffen the towbar assembly 30 and also replaces stiffeners 5. The remaining components shown in Figures 7 to 9 are similar to those shown in Figures 1 to 6 and are therefore designated by like numerals. The components are generally welded together in a similar way to that shown in Figure 3, except for the attachment of the lower crossmember which is i •welded to the bottom edge of the outer angle/apron 2' and to the dropper plates 4. The welds 15 attaching the inner angle 1, outer angle/apron 2' and lower crossmember 6' are shown in Figure 9. The dropper plates 4 and chassis end plates 3 are welded to the inner angle 1 and Sthe outer angle/apron 2' but these are not shown in Figure 9.

The supply line brackets 8 are welded on to the outer angle/apron 2, 2' but the welds are not shown on the drawings.

The pin coupling assembly 10' and the ball coupling assembly 10 are both well known in the art and there is therefore no effort made to describe the workings of these coupling assemblies.

In summary, embodiments of the present invention have the following advantages Because the size of the inner and outer angles 1, 2, 2' is not limited by mill availability, it is possible to make the outer angle 2, 2' slightly larger than the inner angle 1, therefore concealing the welds from normal view and providing a neat, professionally fabricated appearance.

The material thickness of the apron 2, 2' and the inner angle 1 can be 16 mm, or 12 mm to suit a lighter loaded truck, neither of which thickness has been used for towbar assemblies ofthis type.

The lesser width of the bottom of the apron allows clearance for various truck suspension components, brake components or other vehicle components to be housed under the chassis P:\OPER\SSB\TOWBAR.SPE 11/5/00 -7- (eg. the air brakes).

The apron 2, 2' can extend downward and form part of the structure, which is required at a lower level than the chassis, to mount various tow couplings.

The apron 2, 2' is adaptable at the sub-assembly stage for mounting a variety of tow couplings and the height of the apron 2, 2' can be varied to suit specific requirements.

The length of the apron 2, the stiffeners 5 and the dropper plates 4 can be shortened to meet specific height requirements of the type of tow coupling assembly 10, 10' to be used.

These items can be produced to meet the longest case requirements and can be shortened as required for a specific application.

It will be appreciated by a person skilled in the art that there may be a number of modifications or alterations which can be made to embodiments of the present invention described hereinbefore without departing from the spirit and scope of the present invention.

*oo .o°

Claims

1. A towbar assembly including a towbar beam and a tow coupling assembly connected to the towbar beam for forming a tow coupling between first and second vehicles, the towbar beam being formed from first and second L-shaped elongate members, the first member having first and second legs and the second member having third and fourth legs, said first and second members being juxtaposed to one another and joined to make a hollow beam of •generally rectangular section with the first leg being generally parallel to the third leg and the •second leg being generally parallel to the fourth leg, wherein at least a part of the first leg is longer than the third leg to thereby define an apron to which the tow coupling assembly is connected.

2. The towbar assembly of claim 1, wherein the apron has a lesser width than the distance between opposing ends of the first member.

3. The towbar assembly of claim 1 or 2, wherein the part of the first leg defining the apron is generally T-shaped, with the apron forming the bottom of the T-shape. ooooo

4. The towbar assembly of any one of the preceding claims, including chassis end plates connected to the towbar beam at opposing ends thereof for connecting the towbar assembly to the chassis of the first vehicle.

The towbar assembly of any one of the preceding claims, wherein the tow coupling assembly includes a ball assembly.

6. The towbar assembly of claim 5, including a lower crossmember interconnecting the apron and the ball assembly.

7. The towbar assembly of any one of claims 1 to 4, wherein the tow coupling assembly includes a pin coupling assembly. P:\OPER\SSB\TOWBAR.SPE 1115/00 -9-

8. The towbar assembly of claim 7, including a lower crossmember connected to the second member and to the apron at the bottom thereof for strengthening the towbar assembly.

9. The towbar assembly of claim 7 or 8, wherein the pin coupling assembly is removably connected to the apron. The towbar assembly of any one of claims 1 to 4, wherein the tow coupling assembly includes a hook coupling assembly.

10

11. The towbar assembly of claim 6, wherein stiffening plates join the second member with the lower crossmember for strengthening the towbar assembly.

12. The towbar assembly of claim 11 or 8, wherein dropper plates are connected to the first member, second member and the lower crossmember to strengthen the towbar assembly.

13. The towbar assembly of any one of the preceding claims, wherein the first leg has at o least two safety chain attachments joined thereto for releasably attaching safety chains connected to the second vehicle.

14. The towbar assembly of any one of the preceding claims, wherein the first and second members are initially flat and are formed in an L-shape by use of a pressing machine.

The towbar assembly of any one of the preceding claims, wherein the first and second members are joined by at least one weld.

16. The towbar assembly of claim 12, wherein the first member, second member, chassis end plates, lower crossmember, and dropper plates are joined by welds.

17. The towbar assembly of claim 11, wherein the tow coupling assembly is joined to the lower crossmember by welds and the stiffening plates are joined to the second member and lower crossmember by welds. P:\OPER\SSB\TQWBAR.SPE 11/5/00

18. The towbar assembly of claim 15, 16 or 17, wherein the welds are fillet welds.

19. The towbar assembly of claim 12, wherein the first member, second member, chassis end plates, lower crossmember, stiffening plates and dropper plates are formed of steel plates. The towbar assembly of claim 19, wherein the thickness of at least the first member and the second member is about 16 mm.

S

21. The towbar assembly of claim 19, wherein the thickness of at least the first member and the second member is about 12 mm.

22. A towbar beam including first and second L-shaped elongate members, the first member having first and second legs and the second member having third and fourth legs, S said first and second members being joinable in juxtaposition to one another to make a hollow beam of generally rectangular section with the first leg being generally parallel to the third leg and the second leg being generally parallel to the fourth leg, wherein at least a part of the first leg is longer than the third leg to thereby define an apron for connecting thereto a tow coupling assembly.

23. The towbar beam of claim 22, wherein the apron has a lesser width than the distance between opposing ends of the first member.

24. The towbar beam of one of claims 22 or 23, wherein the first and second members are formed of steel plates.

The towbar beam of claim 24, wherein the thickness of the steel plates is about 16 mm.

26. The towbar beam of claim 24, wherein the thickness of the steel plates is about 12 mm. PA0PER\SSB\T0WBAR.SPE 11/I5/00 -11 I-

27. A towbar assembly substantially as hereinbefore described with reference to Figures 1 to 6.

28. A towbar assembly substantially as hereinbefore described with reference to Figures 7 to 9.

29. A towbar beam substantially as hereinbefore described with reference to, and as depicted in, the drawings. 00 *00.. @0.00 0040 00004 0 DATED this eleventh day of May 2000 BARTLETT TRANSPORT IMPROVEMENTS PTY. LTD. By its Patent Attorneys DAVIES COLLISON CAVE