AU2021209291A1

AU2021209291A1 - Converter dolly hitch improvements

Info

Publication number: AU2021209291A1
Application number: AU2021209291A
Authority: AU
Inventors: Ken Pitt
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-07-29
Filing date: 2021-07-29
Publication date: 2023-02-16

Abstract

The present disclosure generally relates to a road train dolly, also known as a converter dolly. In a particular form the present disclosure relates to a hitch assembly for such a dolly, and to a drawbar incorporating such a hitch assembly. In one aspect, there is provided a hitch assembly comprising a mount for mounting the hitch assembly with respect to a drawbar, a hitch, and a means for absorbing impacts incident to the drawbar. In one form, said means for absorbing impacts comprises a sacrificial element. In an alternative form, said means for absorbing impacts comprises a resilient element. 44 002

Description

CONVERTER DOLLY HITCH IMPROVEMENTS TECHNICAL FIELD

[0001] The present disclosure generally relates to a road train dolly, also known as a converter dolly. In a particular form the present disclosure relates to a hitch assembly for such a dolly, and to a drawbar incorporating such a hitch.

BACKGROUND

[0002] A road train is a heavy vehicle combination in which a leading semi-trailer couples directly to a prime mover, and a following semi-trailer is coupled to a preceding semi-trailer via a converter dolly.

[0003] A converter dolly is essentially an axle group having a coupling arrangement to couple with the following semi-trailer and a drawbar that attaches to the preceding semi-trailer.

[0004] A typical dolly comprises a frame carrying a fifth wheel or turntable and supported on one or more axles, and a hinged drawbar comprising a hitch.

[0005] The drawbar typically comprises an A-frame, and the hitch is rigidly fixed with respect to the drawbar at or near to an apex of the A-frame, typically by welding.

[0006] Semi-trailers are required to have a rear underride or impact guard comprising a continuous rear bumper bar. These arrangements are designed to prevent smaller vehicles from sliding underneath the trailer in the event of a rear-end collision. However, it is a common occurrence in road train operations that the road train must perform a turn (whether forwards or while reversing) that is tight enough that a portion of the drawbar of the converter dolly and a portion of the rear impact guard of the trailer to which the converter dolly is hitched collide. During such a tight turn it is a common occurrence for the collision between the drawbar and the rear impact guard to be so hard that the drawbar is bent or otherwise broken, potentially rendering the dolly unserviceable and/or unroadworthy, and potentially without the driver knowing that the damage has occurred until they next stop and inspect their road train. The quickest way to return the unserviceable dolly to a serviceable condition is to replace the entire drawbar and hitch assembly.

[0007] However, many times this connection operation, and thus the damage, is performed 'on the road', far from a replacement dolly, service facilities or replacement parts, meaning repair involves considerable downtime and cost.

[0008] It is against this background that the present disclosure has been developed.

SUMMARY

[0009] According to a first aspect, there is provided a hitch assembly for a drawbar of a converter dolly, the hitch assembly comprising a mount for mounting the hitch assembly with respect to a drawbar, a hitch, and at least one means for absorbing impacts incident to the drawbar.

[0010] In one form, the hitch assembly is configured for retrofit to a drawbar assembly.

[0011] According to a second aspect, there is provided a drawbar assembly for a converter dolly, the drawbar assembly comprising a drawbar, a hitch assembly mounted with respect to the drawbar, the hitch assembly comprising a hitch, and at least one means for absorbing impacts incident to the drawbar assembly.

[0012] In one form, the means for absorbing impact maintains the hitch in a towing position, or straight ahead.

[0013] In one form, the hitch is pivotably mounted with respect to the drawbar, but prevented from pivoting by the means for absorbing impacts incident to the drawbar assembly.

[0014] In one form, in an alternative, the hitch is translationally mounted with respect to the drawbar, but prevented from translating by the means for absorbing impacts incident to the drawbar assembly.

[0015] In one form, the means for absorbing impacts incident to the drawbar assembly comprises at least one resilient element.

[0016] In this form, in use, the hitch will pivot when the incident impact is sufficient to overcome a bias of the or each resilient element.

[0017] In one form, the or each resilient element will return the hitch to the towing position after the impact.

[0018] In one form, the means for absorbing impacts incident to the drawbar assembly comprises at least one sacrificial element.

[0019] In this case, in use, the hitch will pivot when the incident impact is of sufficient magnitude that it exceeds a failure limit of the or each sacrificial element.

[0020] In one form, the failure limit of the or each sacrificial element is lower than a yield point of a remainder of the drawbar assembly.

[0021] In one form, the drawbar comprises amount for the hitch assembly.

[0022] In one form, the drawbar comprises an A-frame, and the mount for the hitch assembly is positioned at or near to an apex of the A-frame.

[0023] In one form, the hitch is pivotably connected with respect to the mount.

[0024] In one form, the hitch comprises an elongate body comprising an eyelet.

[0025] In one form, the or each resilient element comprises a spring element.

[0026] In one form, the or each resilient element comprises a helical spring.

[0027] In one form, the or each resilient element comprises an elastomeric element.

[0028] In one form, the resilient element comprises a rubber or synthetic rubber material.

[0029] In one form, a combination of these different resilient element types may be employed.

[0030] In one form, the resilient element is selected to yield before any of a remainder of the drawbar assembly.

[0031] In one form, the or each sacrificial element comprises a shear pin.

[0032] In one form, the or each sacrificial element comprises a shear bolt.

[0033] In one form, the or each sacrificial element comprises a shear key.

[0034] In one form, a combination of these different sacrificial element types may be employed.

[0035] In one form, in use, the hitch will pivot when the incident impact is sufficient to shear the or each sacrificial element.

[0036] In one form, the or each sacrificial element comprises a weld.

[0037] In one form, the or each sacrificial element comprises a cured adhesive.

[0038] According to a further aspect, there is provided a drawbar assembly for a converter dolly, the drawbar assembly comprising a drawbar, a hitch assembly comprising a hitch, and at least one means for absorbing impacts incident to the drawbar assembly, wherein the hitch is pivotably mounted with respect to the drawbar, but prevented from pivoting by the means for absorbing impacts incident to the drawbar assembly.

[0039] According to a further aspect, there is provided a drawbar assembly for a converter dolly, the drawbar assembly comprising a drawbar, a hitch assembly comprising a hitch, and at least one means for absorbing impacts incident to the drawbar assembly, wherein the hitch is pivotably mounted with respect to the drawbar, but prevented from pivoting by the means for absorbing impacts incident to the drawbar assembly, which comprises at least one sacrificial element.

[0040] According to a further aspect, there is provided a drawbar assembly for a converter dolly, the drawbar assembly comprising a drawbar, a hitch assembly comprising a hitch, and at least one means for absorbing impacts incident to the drawbar assembly, wherein the hitch is pivotably mounted with respect to the drawbar, but prevented from pivoting by the means for absorbing impacts incident to the drawbar assembly, which comprises at least one resilient element.

[0041] According to a further aspect, there is provided a converter dolly comprising the above described draw bar assembly.

[0042] In one form, the converter dolly is an A-dolly, comprising a single hitch assembly.

[0043] In one form, in an alternative, the dolly is a C-dolly comprising a pair of hitch assemblies.

[0044] For ease of description, a drawbar and a hitch assembly embodying the present features are described below in their usual assembled position as shown in the accompanying drawings and terms such as front, rear, upper, lower, horizontal, longitudinal etc., may be used with reference to this usual position. However, the drawbar and hitch assembly may be manufactured, transported, sold, or used in orientations other than that described and shown here.

BRIEF DESCRIPTION OF DRAWINGS

[0045] The present disclosure will be discussed with reference to the accompanying drawings wherein:

[0046] Figure 1 is a perspective view of a drawbar assembly for a converter dolly in a normal, in-use or un-deflected configuration;

[0047] Figure 2 is a top view of the drawbar assembly of Figure 1;

[0048] Figure 3 is a front end view of the drawbar assembly of Figure 1;

[0049] Figure 4 is a top view of the drawbar assembly of Figure 1 in a deflected configuration;

[0050] Figure 5 is a front end view of the drawbar assembly of Figure 4;

[0051] Figure 6 is a perspective view of a hitch from the drawbar assembly of Figure 1;

[0052] Figure 7 is a top view of the hitch of Figure 6;

[0053] Figure 8 is a front end view of the hitch of Figure 6;

[0054] Figure 9 is a top view of a hitch assembly according to a further aspect;

[0055] Figure 10 is a side view of the hitch assembly of Figure 9;

[0056] Figure 11 illustrates a converter dolly hitched to a semitrailer; and

[0057] Figure 12 is a detail view of the drawbar from the converter dolly of Figure 11.

[0058] In the following description, like reference characters designate like or corresponding parts throughout the figures.

DESCRIPTION OF EMBODIMENTS

[0059] Referring now to Figure 1, where there is illustrated a drawbar assembly 1 for a road train dolly, also known as a converter dolly 100.

[0060] With reference to Figures 11 and 12, it can be seen that the converter dolly 100 comprises a chassis 102 riding on an axle group (i.e. typically one, two or three of axle assemblies 104) and supporting a coupling arrangement 106 to which a following semitrailer (not illustrated) can be connected. Typically this coupling arrangement 106 comprises a fifth-wheel coupling. The converter dolly 100 further comprises the drawbar assembly 1 comprising a hitch assembly 10 comprising a hitch 11 via which the converter dolly 100 can be connected to a preceding semi-trailer 120. The drawbar assembly 1 is pivotably connected to the chassis 102 so that the hitch assembly 10 can swing through a vertical arc, to account for relative movement of the preceding semi-trailer 120.

[0061] With reference to Figures I to 5, it can be seen that the drawbar assembly 1 comprises an A frame comprising a pair of converging frame members 2, and a mount 4 for the hitch assembly 10 positioned at or near to an apex of the A-frame. The mount 4 could be fabricated as a part of the drawbar assembly 1, or configured to be retrofit thereto such as by bolting.

[0062] The mount 4 comprises a pair of mounting plates 6a and 6b. A first mounting plate 6a is secured to a top of the A-frame, and a second mounting plate 6b is secured to an underside of the A-frame. Between the mounting plates 6a and 6b is a space for receiving the hitch 11. Each of the mounting plates 6a and 6b comprises a matching mounting hole, and these two mounting holes are aligned so that they may receive a mounting pin 30.

[0063] Referring now to Figures 6, 7 and 8, the hitch 11 is, in the case of the arrangement illustrated, a welded assembly, comprising a ring drawbar 12 comprising an elongate body 13 and an eyelet 14 at one end. The eyelet 14 is adapted for connection to a pintle hitch 122 (see Figure 12) or hook which will be secured with respect to a back end of the semi-trailer 120 which is to precede the dolly 100.

[0064] The hitch 11 further comprises a pair of shear plates 16a and 16b. A first shear plate 16a is secured to a top of the ring drawbar 12, and a second shear plate 16b is secured to an underside of the ring drawbar 12. Each of the shear plates 16a and 16b comprises a matching collar hole, and these two collar holes are aligned. The hitch 11 further comprises a mounting collar 18 at a further end (distal to the eyelet 14) which extends into and between the collar holes in the two shear plates 16a and 16b, and which defines a through mounting hole 20 that matches the mounting holes in the mounting plates 6a and 6b.

[0065] Each of the shear plates 16a and 16b further comprises a matching pin hole 42 and these two holes 42 are aligned so that these may receive a sacrificial element in the form of a shear pin 40. Each of the mounting plates 6a and 6b similarly comprises a matching pin hole for the shear pin 40.

[0066] The hitch 11 is pivotably connected with respect to the mounting plates 6a and 6b by way of the mounting pin 30 passing through the aligned mounting holes in each of the hitch 11 and the mounting plates 6a and 6b.

[0067] The hitch 11 is prevented from pivoting with respect to the remainder of the drawbar assembly 1 by the shear pin 40 (in the form of a bolt in this case) passing through each of the matching and aligned pin holes 42 provided therefor in each of the shear plate 16a and 16b and the mounting plates 6a and 6b. This might be described as a normal, in-use or un-deflected configuration for the hitch assembly.

[0068] The upper mounting plate 6a comprises a line of reserve holes 44 for receiving spare shear pins 40.

[0069] These sacrificial elements will be of such a size and material that the failure limit of these is lower than a yield point of a remainder of the drawbar assembly. That is to say, they should fail before anything else in the drawbar assembly approaches a failure condition.

[0070] Referring to Figure 12, in use, should the road train perform a turn which is so tight that one of the drawbar frame members 2 and a portion (such as uprights 132) of a rear impact guard 130 (or another portion) of the semi-trailer 120 collide with sufficient force, then the shear pin 40 will shear, permitting the hitch 11 to swing about its mounting pin 30, as illustrated in Figures 4 and 5, thereby preventing the remainder of the drawbar assembly 1 from incurring any damage.

[0071] Should this happen, the hitch 11 can be straightened, and a spare shear pin 40 removed from one of the reserve holes 44 inserted into the aligned matching pin holes 42 therefor. In this way, the converter dolly of which the drawbar assembly 1 is a part, can be returned to service with minimal downtime and cost.

[0072] Referring now to Figures 9 and 10, where there is illustrated a drawbar assembly according to a further aspect. Those parts of the drawbar assembly la which are identical (or near- identical) to corresponding parts shown in the drawbar assembly 1 of Figures 1 through 8, will be denoted by the same reference numerals and will not be described again in detail.

[0073] Drawbar assembly la differs from drawbar assembly 1 principally in that instead of a sacrificial means for absorbing impact, a resilient means is employed.

[0074] As before, the hitch 11 comprises a ring drawbar 12 comprising an elongate body 13 and an eyelet 14 at one end, and a mounting collar 18, but in this instance the elongate body 13 extends beyond the mounting collar 18. This portion of the body 13 extending beyond the mounting collar 18 will be referred to as a 'tail portion' 13a of the hitch 11.

[0075] To either side of the tail portion 13a of the hitch11 there is positioned a resilient element in the form of a helical spring 50. Each of these springs 50 is substantially identical, and secured with respect to an inner surface of one of the drawbar frame members 2 in an opposing fashion. At its outer end, each of these springs caries a bump stop 52 which bears against a side of the tail portion 13a of the hitch 11.

[0076] In normal use, the two springs 50 will cooperate to maintain the hitch 11 in a straight alignment for towing.

[0077] In the case that the road train should perform a turn which is so tight that the one of the drawbar frame members 2 and a portion (such as uprights 132) of a rear impact guard 130 (or another portion) of the semi-trailer 120 collide, then the springs 50 will permit the hitch 11 to swing about its mounting pin , thereby absorbing impact and preventing the remainder of the drawbar assembly la from incurring any damage. The springs 50 will then eventually return the hitch 11 to its straight alignment for towing, so that minimal downtime is lost.

[0078] These resilient elements should be selected so that they will deflect before anything else in the drawbar assembly approaches a failure condition.

[0079] A non-illustrated aspect of the drawbar might employ both the sacrificial and resilient means. This would enjoy the advantage of the shear pin 40 to maintain the hitch 11 in a straight ahead alignment, and the resilient springs 50 to restore this straight ahead alignment if the sacrificial shear pins 40 are sheared.

[0080] In a further non-illustrated aspect the hitch 11 is translationally mounted with respect to the drawbar. This is achievable by way of retaining the mounting pin 30 within a slot formed into the mounting plates 6a and 6b, and the hitch 11 being prevented from moving by either of the resilient or sacrificial means until impacted upon.

[0081] Advantageously, the present disclosure provides aspects which will minimise downtime and cost associated with damage arising from turning road trains, whether forwards or while reversing.

[0082] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that such prior art forms part of the common general knowledge.

[0083] It will be understood that the terms "comprise" and "include" and any of their derivatives (e.g. comprises, comprising, includes, including) as used in this specification, and the claims that follow, is to be taken to be inclusive of features to which the term refers, and is not meant to exclude the presence of any additional features unless otherwise stated or implied.

[0084] In some cases, a single embodiment may, for succinctness and/or to assist in understanding the scope of the disclosure, combine multiple features. It is to be understood that in such a case, these multiple features may be provided separately (in separate embodiments), or in any other suitable combination. Alternatively, where separate features are described in separate embodiments, these separate features may be combined into a single embodiment unless otherwise stated or implied. This also applies to the claims which can be recombined in any combination. That is a claim may be amended to include a feature defined in any other claim. Further a phrase referring to "at least one of' a list of items refers to any combination of those items, including single members. As an example, "at least one of: a, b, or c" is intended to cover: a, b, c, a-b, a-c, b-c, and a-b-c.

[0085] It will be appreciated by those skilled in the art that the disclosure is not restricted in its use to the particular application or applications described. Neither is the present disclosure restricted in its preferred embodiment with regard to the particular elements and/or features described or depicted herein.

It will be appreciated that the disclosure is not limited to the embodiment or embodiments disclosed, but is capable of numerous rearrangements, modifications and substitutions without departing from the scope as set forth and defined by the following claims.

Claims

1. A drawbar assembly for a converter dolly, the drawbar assembly comprising a drawbar, a hitch assembly mounted with respect to the drawbar, the hitch assembly comprising a hitch, and at least one means for absorbing impacts incident to the drawbar assembly.

2. The drawbar assembly of claim 1, wherein the hitch assembly is pivotably mounted with respect to the drawbar, but prevented from pivoting by the means for absorbing impacts incident to the drawbar assembly.

3. The drawbar assembly as in either of the preceding claims, wherein the hitch assembly is pivotably mounted with respect to a mount, via which the hitch assembly is mounted with respect to the drawbar.

4. The drawbar assembly as in either of claims 2 or 3, wherein the hitch assembly comprises a mounting pin for pivotably mounting the hitch with respect to the drawbar.

5. The drawbar assembly as in any one of the preceding claims, wherein the means for absorbing impacts incident to the drawbar assembly comprises at least one sacrificial element.

6. The drawbar of claim 5, wherein the at least one sacrificial element comprises a shear pin.

7. The drawbar of claim 6, wherein the or each shear pin pins the hitch with respect to the drawbar.

8. The drawbar as in either of claims 6 or 7 when these depend from claim 3, wherein the or each shear pin pins the hitch with respect to the mount.

9. The drawbar assembly as in any one of claims 1 through 4, wherein the means for absorbing impacts incident to the drawbar assembly comprises at least one resilient element.

10. The drawbar assembly as in any one of claims 1 through 4, wherein the means for absorbing impacts incident to the drawbar assembly comprises at least a pair of oppositely directed resilient elements.

11. The drawbar assembly of claim 10, wherein each of the pair of oppositely directed resilient elements bears against the hitch.

12. The drawbar assembly as in any one of claims 9 through 11, wherein the or each resilient means comprises a spring.

13. The drawbar assembly as in any one of claim 9 through 12, wherein the or each resilient means comprises a helical spring.

14. The drawbar assembly of claim 1, wherein the hitch assembly is translationally mounted with respect to the drawbar, but prevented from moving translationally by the means for absorbing impacts incident to the drawbar assembly.

15. The drawbar assembly as in any one of the preceding claims, wherein the means for absorbing impacts incident to the drawbar assembly comprises at least one sacrificial element and at least one resilient element.

16. A drawbar assembly for a converter dolly, the drawbar assembly comprising a drawbar, a hitch assembly comprising a hitch, and at least one means for absorbing impacts incident to the drawbar assembly, wherein the hitch is pivotably mounted with respect to the drawbar, but prevented from pivoting by the means for absorbing impacts incident to the drawbar assembly.

17. A drawbar assembly for a converter dolly, the drawbar assembly comprising a drawbar, a hitch assembly comprising a hitch, and at least one means for absorbing impacts incident to the drawbar assembly, wherein the hitch is pivotably mounted with respect to the drawbar, but prevented from pivoting by the means for absorbing impacts incident to the drawbar assembly, which comprises at least one sacrificial element.

18. A drawbar assembly for a converter dolly, the drawbar assembly comprising a drawbar, a hitch assembly comprising a hitch, and at least one means for absorbing impacts incident to the drawbar assembly, wherein the hitch is pivotably mounted with respect to the drawbar, but prevented from pivoting by the means for absorbing impacts incident to the drawbar assembly, which comprises at least one resilient element.

19. A converter dolly comprising a drawbar assembly as in any one of the preceding claims.

20. A hitch assembly for a drawbar of a converter dolly, the hitch assembly comprising a mount for mounting the hitch assembly with respect to a drawbar, a hitch, and at least one means for absorbing impacts incident to the drawbar.

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