NZ549244A - A coupling - Google Patents

Abstract

A trailer coupling for fastening a trailer vehicle to a tow ball of a towing vehicle including: a coupling structure configured with a socket and retention member wherein the socket and retention member are configured to capture a first size tow ball with the coupling structure in a primary position, and configured to capture a differently size tow ball with the coupling structure in a secondary position, characterised in that the tow ball is captured with the coupling structure in the secondary position if not held when in the primary position.

Description

*10054669357* j '^/^r / '7 *<* 200? j F C E i y c r; —j PATENTS FORM NO. 5 Fee No. 4: $250.00 PATENTS ACT 1953 COMPLETE SPECIFICATION After Provisional No: 549244 Dated: 17 August 2006 A COUPLING WE T-FORCE NZ LIMITED, a New Zealand company of 108 Jervois Street, Dargaville, NEW ZEALAND hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement: James & Wells Ref: 231717/61 LR 549244 A COUPLING Technical Field The present invention relates to a coupling.

Particularly, although not exclusively, the present invention relates to a trailer 5 coupling configured for use with different sized tow balls.

Background Art Trailer couplings are provided on the draw bar of a trailer to allow for a trailer to be coupled to a tow ball provided on a vehicle.

An ideal connection between the trailer and vehicle provides a safe and secure 10 connection with a relatively free range of movement between the vehicle and the trailer.

Whilst transport regulations only provide for a 50 mm tow ball, 1 7/8" tow balls have continued to be fitted to vehicles, and make up around 90% of tow balls sold.

A particular sized tow ball requires for a complimentary sized trailer coupling to be 15 configured to allow for effective and safe towing of the trailer.

Generally, there are no difficulties experienced for people who own a matching trailer coupling to the tow ball on their vehicle.

However, problems arise when a trailer with a specific coupling size is to be towed by a vehicle fitted with a different sized tow ball.

For instance, these problems commonly arise where trailers are provided for hire. 2 James & Wells Ref: 231717/61 LR 549244 Where an existing tow ball is provided on the vehicle, it must be matched by the coupling on the trailer being hired.

Where the tow ball is of a larger size (50 mm), and where the coupling is adapted for a smaller sized tow ball (1 7/8"), a coupling cannot by achieved.

The reverse is not true, as should the tow ball be 1 7/8 inch, it is possible to intentionally or unintentionally connect a coupling adapted for 50 mm tow balls to it.

A 1 7/8 inch tow ball is equivalent to 47.6 mm, which means that although it readily fits into a 50 mm coupling, however, the fitting is loose and therefore not secure.

This creates a dangerous situation, as depending on the load and conditions, the 10 trailer may disconnect with potentially dire consequences.

There is a real danger of trailers detaching from vehicles due to confusion regarding two sizes of tow ball that are accepted in New Zealand and both widely available.

The predominance of 1 7/8 inch tow balls means it is common to see 50 mm 15 couplings mis-matched with them. The risk of detachment is further elevated if the tow ball or coupling is at all worn.

Since this size mismatch is not easily detected, a driver may be completely unaware of the risk this presents.

Even if the trailer remains connected with the safety chain, there is still significant 20 potential for an accident to happen. Unless a driver has been informed of the size difference, a driver could be completely unaware of the potential danger.

All present coupling mechanisms have either a static open position, a non coupling 3 James & Wells Ref: 231717/61 LR 549244 position and/or an insecure closed position. In either case, the trailer may be, and commonly is, inadvertently towed with the hitching process incomplete.

In the meantime there are some products in the industry that attempt to address some of these problems.

Convert-A-Ball™ Hitch System Products and others, which provide an interchangeable ball system (1 7/8 inch, 2 5/16 inch and 50 mm) fitted on a universal shank.

The balls can be interchanged by some mechanism, e.g. by removing a central pin, which can be pushed out with the tip of a key or pen while the shank remains 10 firmly attached to the tow bar.

However, the disadvantages of this invention are that the alternate tow ball needs to be carried in the tow vehicle and can become lost, is expensive to replace, and time consuming to interchange. Further, the cost of these inter-changeable ball systems is high.

Any product that requires user intervention still leaves the potential for someone to mistakenly hitch a trailer fitted with a 50 mm coupling to a 1 7/8 inch tow ball.

New Zealand Patent No. 512280 relates to a trailer coupling which allows for a coupling to be achieved with at least two different sized tow balls. These are marketed as Trojan Duofit couplings.

These couplings accommodate both 1 7/8 inch and 50 mm tow balls by lifting and rotating the plunger to suit.

A primary disadvantage of this invention is that it requires operator skill and intervention to match the correct plunger profile with the matching ball size. 4 James & Wells Ref: 231717/61 LR 549244 Therefore, compared to a standard 1 7/8" coupling, it actually increases the potential for someone to mistakenly hitch a trailer with the coupling turned to the 50 mm setting on a 1 7/8 inch tow ball.

The placement of the retention surfaces are diametrically opposed on the retention 5 member (plunger), and this means that the plunger is effectively weakened in the load bearing zone. Further, the 50 mm retention surface, being the larger metal removal, provides even less support when the most critical condition (1 7/8 inch tow ball in a 50 mm socket) is occurring. Thus significantly less plunger support exists than occurs in fixed size couplings of a similar plunger mechanism.

All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinency of the cited documents. It will be clearly understood that, although a 15 number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in New Zealand or in any other country.

It is acknowledged that the term 'comprise' may, under varying jurisdictions, be attributed with either an exclusive or an inclusive meaning. For the purpose of this 20 specification, and unless otherwise noted, the term 'comprise' shall have an inclusive meaning - i.e. that it will be taken to mean an inclusion of not only the listed components it directly references, but also other non-specified components or elements. This rationale will also be used when the term 'comprised' or 'comprising' is used in relation to one or more steps in a method or process.

It is an object of the present invention to address the foregoing problems and James & Wells Ref: 231717/61 LR 549244 others, or at least to provide the public with a useful choice.

Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.

Disclosure of Invention According to one aspect of the present invention there is provided a trailer coupling for fastening a trailer vehicle to a tow ball of a towing vehicle including: a coupling structure configured with a socket and retention member wherein the socket and retention member are configured to capture a first size tow ball with the coupling structure in a primary position, and configured to capture a differently sized tow ball in a secondary position, characterised in that, the tow ball is captured with the coupling structure in the secondary position if not held when in the primary position.

A particular aspect of the present invention is that the adjustment of the retention 15 member from the primary to the secondary position is entirely automatic, and does not require operator skill or intervention. Further, the initiation of towing pulls the tow ball forward into the coupling socket, providing the ideal circumstance for the retention member to fully engage if it has not already done so.

According to another aspect of the present invention there is provided a trailer 20 coupling wherein the retention member has multiple recesses of different sizes for co-operating with different size tow balls, characterised in that, 6 James & Wells Ref: 231717/61 LR 549244 the retention member is biased towards the tow ball to cause the retention member to be positioned so that the appropriate sized recess co-operates with the tow ball.

Throughout the present specification the term 'coupling structure' should be understood to mean a mechanical device that connects two or more things namely 5 a tow vehicle and trailer.

Throughout the present specification the term primary and secondary positions are defined as the discrete ball engaging surface areas of the retention member respectively. For example, the primary position is where a smaller size 1 7/8 inch diameter tow ball is retained and the secondary position is where a larger size 50 10 mm diameter tow bail is retained.

Where reference is made to a trailer, it is understood to mean a diverse range of wheeled carriages and may include a domestic garden trailer, boat trailer, caravan, industrial, recreational, transportation trailer or any other such trailer that is found or drawn behind a vehicle.

The trailer coupling is engagable with a tow ball of a vehicle such as a car, ute, truck or any other such vehicle.

In preferred embodiments of the present invention the coupling structure is cast in a suitable metal with a protective coating.

However, this should not be seen as a limitation on the embodiments envisaged for 20 this invention. Other embodiments envisaged include, but are not limited to zinc plated pressed steel, aluminium, composite or any other such material.

In preferred embodiments the coupling structure may include provision for a braking mechanism such as electric or hydraulic assisted braking systems well 7 James & Wells Ref: 231717/61 LR 549244 known in the trailer industry.

The socket or ball cavity is preferably substantially complimentary to the shape of at least part of the tow ball. This is a region of the coupling structure where the tow ball can enter from beneath.

Throughout the present specification the term 'retention member' should be understood to mean the movable component which is configured to retain the tow ball in the coupling cavity. The retention member is moveable between a release position and a single or multiple retaining position/s.

In preferred embodiments the retention member has single or multiple (at least two 10 or more) retention features. For ease of reference throughout the specification, the retention member may now be simply referred to as a plunger.

These retention surfaces provide a discrete ball contact surface, one for each ball diameter.

Preferably, the ball contact surfaces are for a 1 7/8 inch and/or 50 mm diameter 15 ball.

However, this should not be seen as a limitation of the present invention as any size diameter ball known in the industry may be accommodated such as a 2 5/16 inch ball.

In preferred embodiments the retention feature(s) are a combination of ball sized 20 matching spherical and cylindrical or 'scalloped' surfaces on the plunger in a manner such that one or the other is provided to engage with the matching sized tow ball in the retained position.

However, this should not be seen as a limitation of the present invention. A scallop 8 James & Wells Ref: 231717/61 LR 549244 shape is not essential as any correctly dimensioned ball contact surface on the plunger would also achieve ball retention. Other variants of surface profile may include V-Forms, flats etc.

The plunger can be made from any material with a suitable compressive strength.

The form of the plunger allows for precise controlled of the ball cavity to plunger retention feature dimension. This ensures minimal looseness of the retained tow ball.

In preferred embodiments the plunger is configured with a 'T-slot' profile, which provides the advantage of transmitting all of the tow ball load directly to the 10 coupling body for maximum strength. Further, the 'T-slot" effect ensures the plunger is suitably retained in all directions except that required for engagement and release of the towball.

The form of the plunger/coupling interface provides stable support of the plunger under all load conditions. Simple compressive loads only are present in use.

In preferred embodiments of the present invention a spring or springs is largely or entirely located within the plunger. The advantage is that this reduces the overall height profile of the coupling whilst still allowing full operational movement of the plunger.

An alternate aspect of the present invention provides a trailer coupling for fastening 20 a trailer vehicle to a tow ball of a towing vehicle including: a coupling structure having a socket, and a retention member, 9 James & Weils Ref: 231717/61 LR 549244 characterised in that the retention member is in the form of a plunger biased towards the tow ball to cause the retention member to be positioned so that the socket co-operates with the tow ball.

While in preferred embodiments this invention is configured to co-operate with 5 different sized tow balls, this is not necessarily the case. For example, the retention member may only have contours (scalloping, flats etc) that fit with one-sized ball only thus providing all the other benefits of this invention to the user.

The coupling structure may be configured with any of a variety of plunger release mechanisms. This mechanism may including, but is not limited to, levers, 10 hydraulic, electric, cable, mechanical, direct action, air, electronic or other means.

More preferably the coupling structure includes an integrated handle with slotted trigger lever.

The slotted trigger lever may cooperate with the integrated handle. The advantages of this configuration is that it not only gives the coupling aesthetic 15 appeal, but it allows the functions as outlined below: It allows the trigger to drop out of the way when not in use whilst still giving adequate finger clearance to access the trigger, Also, it allows a hand to grip the trigger and be raised parallel to the adjacent integrated handle, thereby giving full support when lifting the coupling off a vehicle.

The support of the handle against the trigger when lifting prevents excess force and damage to the trigger mechanism.

A preferred embodiment of the coupling structure includes an integrated James & Wells Ref: 231717/61 LR 549244 mechanical lock that directly engages the plunger in any retaining position, whether or not the tow ball is present. This provides a security feature whether or not the trailer is connected to the tow vehicle. Also the lock may be fully embedded in the coupling body, which increases robustness. Unlocking may include a simple key 5 mechanism, with only the key to remove or locate.

In preferred embodiments of the present invention there are two lock pin receiving holes arranged parallel to the plunger travel path. This enables the lock to engage in either of the ball engaging positions.

Economically, in the preferred embodiment the operation of the plunger release 10 mechanism does not involve a hand position movement. The advantage of this is that in confined spaces, the operator is not at risk of injury due to fouling whilst releasing the coupling.

A further ergonomic benefit is that releasing the coupling is a contained hand and finger-only operation and does not require resistance from the trailer to achieve.

Equally, engaging the coupling does not require any operator effort apart from placement on the tow ball.

In preferred embodiments of the present invention, a conrod connects the trigger lever to the plunger and is arranged in such away as to allow the plunger to travel the full upward stroke during ball engagement without lifting the trigger lever. This 20 eliminates the possibility of the trigger lever hitting the operators' fingers whilst fitting the coupling to the towball.

The invention retains the tow ball and operates by the following mechanism: A tow ball enters a ball cavity (socket) from beneath the coupling structure. 11 James & Wells Ref: 231717/61 LR 549244 The socket cavity entry tube is mounted on a backward sloping gradient, so that vertical motion forces the tow ball to meet the coupling body rather than escaping the cavity.

As the ball enters the cavity, it contacts the bottom of the plunger which moves it 5 upwards against the retaining spring(s) until the ball is fully entered ("home") into the socket. Alternatively, the operator may lift the plunger by way of the release mechanism. The plunger has two discrete ball contact surfaces, one for each ball diameter (50 mm and 1 7/8 inches), or alternatively, a single contact surface for a particular tow ball diameter.

Once the ball is located and 'home' in the socket, the plunger spring forces the plunger downward to occupy the space between the ball and the rear of the coupling cavity, and is taken up by the matching retention feature on the plunger. The plunger is appropriately dimensioned to retain the ball forward in the socket.

Under an external load, the spherical form of the ball cavity forces the ball to move 15 backwards, whereupon it meets the plunger, thus preventing the tow ball to disengage. This effect occurs regardless of the load direction.

Furthermore, the cavity roof prevents the ball lifting the plunger whilst the spherical shape of the retention feature helps to resist sideways movement of the ball within the socket.

The spherical retention feature is preferred, but not essential, as a correctly dimensioned flat face or other shape forms on the plunger will achieve suitable ball retention.

Further advantages of this invention include a trailer coupling which automatically 12 James & Wells Ref: 231717/61 LR 54924^ adjusts to accommodate a 1 7/8 inch diameter tow ball and/or a 50 mm diameter tow ball. This feature provides the advantages of both eliminating user intervention in the selection of the correct size tow ball/coupling setting, and offers the versatility of being able to hitch up a trailer without any knowledge of tow ball size.

The design of the coupling also allows the flange of a 50 mm diameter tow ball to recede into the plunger slot cavity. The advantage of this is that the coupling can allow a trailer a greater range of articulation for off road/extreme use.

Brief Description of Drawings Further aspects of the present invention will become apparent from the following 10 description which is given by way of example only and with reference to the accompanying drawings in which: All diagrams are for a shaft mounted hydraulic override style coupling assembly. However, the mechanism shown can also be used in all other coupling arrangements, with structural changes to the body exterior to suit. For example, as shown in Figure 7. shows a diagrammatic representation of a cutaway cross-section of one preferred embodiment of the present invention in the retention position with a 1 7/8 inch diameter ball; shows a diagrammatic representation of a cutaway cross-section of one preferred embodiment of the present invention in the retention position with a 50 mm diameter tow ball; shows a diagrammatic representation of a centreline cross-section of one preferred embodiment of the present invention during release Note: Figure 1 Figure 2 Figure 3 13 James & Wells Ref: 231717/61 LR 549244 Figure 4 Figure 5 Figure 6 Figure 7 operation; shows a diagrammatic representation of a cutaway rear view of the plunger of one preferred embodiment of the present invention; shows a diagrammatic representation of a semi cutaway front quarter view of the coupling assembly, of one preferred embodiment of the present invention; and shows diagrammatic representations of the front and rear view of the plunger arrangement of one preferred embodiment of the present invention. shows a diagrammatic representation of a perspective view of an alternative embodiment of the present invention. best Modes for Carrying out the invention With reference to the figures, there is provided a trailer coupling which automatically adjusts to accommodate a 1 7/8 inch diameter tow ball and/or a 50 15 mm diameter tow ball.

The coupling structure and related components are typically manufactured from cast iron and machined steel processes. These materials and processes are well known in the trailer industry and therefore do not need to be described any further.

Figures 1 and 2 show the two size tow balls 1 7/8 inch (4A) and 50 mm (4B) 20 respectively in the retention position of the coupling.

The coupling includes the following componentry; a coupling handle (1), trigger lever (2), lifting rod or conrod (3), plunger (5), coupling body (6), trigger pivot (7), 14 James & Wells Ref: 231717/61 LR 549244 plunger and spring cavity (8) and mounting shaft hole (9).

The plunger (5), is seated down so that the ball (4A) is retained forward into the ball cavity. The trigger lever (2) is in the relaxed position. In comparison the ball cavity is fully occupied when the plunger (5) is seated against the 50 mm ball.

Figure 3 shows the coupling during release operation. The plunger (5) is shown as a full body (not cutaway, so appears to overlap the ball). The spherical form is in fact fully clear of the ball enabling easy passage out of the ball cavity. The trigger lever (2) fits snugly against the handle (1) enabling full operation of the release with finger compression only. Note, the left hand spring has been removed for clarity.

A detailed rear view of the plunger is shown in figure 4 and shows the recessed location of the plunger springs. The conrod (3) that links the trigger lever (2) to the plunger (5) is attached to the plunger by a pin passing through the hole (9). Another pin on which the trigger lever pivots is inserted into hole (7).

A semi cutaway front quarter view of the coupling assembly is shown in figure 5. 15 The plunger (5) is in the 50 mm ball retaining location. The lock pin (17) has been activated and has entered the hole in the plunger (5). The handle (1) is shown in the ready position to contact the plunger position part way through a release stroke.

A detailed front and rear view of the plunger arrangement is shown in figure 6. The plunger (5) is configured with two ball retaining features, (10 and 11) on the front. 20 On one side a two lock pin engagement holes (16). In the rear is a recess feature (12) to locate the two plunger springs. A further recess (13) provides a location for the conrod (3) to reside. The rear load bearing face (14) and forward retaining face (15) is shown.

Figure 7 shows an alternative embodiment that is used for non-braked couplings James & Wells Ref: 231717/61 LR 549244 which includes the following componentry; an integrated handle (1A) with slotted trigger lever (2A). The coupling body (6A) is also configured with a socket and retention member configured to capture two differently sized tow balls as described above and further drawings of the internal mechanism need not be shown.

Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof as defined in the appended claims. 16 549244

Claims (5)

WHAT WE CLAIM IS:

1. A trailer coupling for fastening a trailer vehicle to a tow ball of a towing vehicle including: a coupling structure configured with a socket and retention member wherein the socket and retention member are configured to capture a first size tow ball with the coupling structure in a primary position, and configured to capture a differently sized tow ball in a secondary position, characterised in that, the tow ball is captured with the coupling structure in the secondary position if not held when in the primary position.

2. A trailer coupling as claimed in claim 1, wherein the retention member has multiple recesses of different sizes for co-operating with different size tow balls.

3. A trailer coupling as claimed in claim2, wherein the retention member is biased towards the tow ball to cause the retention member to be positioned so that the appropriate sized recess co-operates with the tow ball.

4. A trailer coupling as claimed in any one of claims 1 to 3, wherein the primary position is where a smaller size 1 7/8 inch diameter tow ball is retained and the secondary position is where a larger size 50 mm diameter tow ball is retained.

5. A trailer coupling as claimed in any one of claims 1 to 4, wherein the retention member is configured with a 'T-slot' profile. Intellectual Property Office of N.Z. ' t h FEB 2006 Dc^ci\/cn 549244 A trailer coupling as claimed in any one of claims 1 to 5, wherein the coupling structure is configured with a retention member release mechanism. A trailer coupling as claims in claim 6, wherein the retention member release mechanism is moveable between a release position and a retaining position. A trailer coupling as claimed in claim 6 or claim 7, wherein the release mechanism includes a trigger lever. A trailer coupling as claimed in any one of claims 1 to 8, wherein a conrod connects the trigger lever to the retention member and is configured to allow the retention member to travel the full upward stroke during ball engagement without lifting the trigger lever. A trailer coupling as claimed in any one of claims 1 to 9, wherein the socket is substantially complimentary to the shape of at least part of the tow ball. A trailer coupling as claimed in any one of claims 1 to 10, wherein the retention member is configured with discrete bail contact surfaces, one for each ball diameter to engage with a matching sized tow ball in the retained position. A trailer coupling as claimed in claim 11, wherein the ball contact surfaces are for a 1 7/8 inch and 50 mm diameter ball. A trailer coupling as claimed in claim 11 or claim 12, wherein the ball contact surfaces are a scallop shape. A trailer coupling as claimed in any one of claims 1 to 13, wherein a spring is predominantly located within the retention member. A trailer coupling as claimed in any one of claims 1 to 14, wherein the Intellectual Property Office of N.Z. ' 1>t FEB 2008 pcrci w e n 549244 coupling structure includes a provision for a braking mechanism. A trailer coupling as claimed in any one of claims 1 to 15, wherein the coupling structure includes an integrated mechanical lock that directly engages the retention member in any retaining position. A trailer coupling as claimed in any one of claims 1 to 16, wherein the coupling structure includes two lock pin receiving holes arranged parallel to the retention member travel path to enable the lock to engage the ball engaging positions. A trailer coupling as substantially herein described with reference to and as illustrated by the accompanying drawings. A trailer configured with a trailer coupling as substantially herein described with reference to and as illustrated by the accompanying drawings. T-FORCE NZ LIMITED by their Attorneys JAMES & WELLS 19 Intellectual Property Office of N.2. ' 1 "i FEB 2008 RECFIVFn