AU720137B2 - Trailing arm coil suspension - Google Patents

Description

I' P/00/011 Regulation 3.2

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT Name of Applicant: Address of Applicant: Actual Inventor: Address for Service: DARRYL JAMES MARTIN 195 Chester Pass Road Chester Pass Industrial Area Albany, Western Australia 6330

AUSTRALIA

DARRYL JAMES MARTIN Griffith Hack, Attorneys, 6th Perth, Western Patent and Trade Mark Floor, 256 Adelaide Terrace, Australia,- 6000.

Standard Complete Specification for the invention entitled: TRAILING ARM COIL SUSPENSION Details of Associated Provisional Applications: PN 9129 filed 4 April 1996 Details of Parent Application for Divisional Applications: The following is a full description of this invention, including the best method of performing it known to me:- 2 TRAILING ARM COIL SUSPENSION FIELD OF THE INVENTION The present invention relates to a trailing arm coil suspension for trailers or the like vehicles and relates particularly, though not exclusively, to an off-road trailer camper fitted with such a trailing arm coil suspension to be marketed under the trade mark XPLORER.

BACKGROUND TO THE INVENTION Trailer campers are becoming increasingly popular with people who enjoy off-road camping for recreational purposes. On the road a camper trailer looks for all intents and purposes like a conventional trailer and can be towed behind a conventional motor vehicle. However, when unfolded and erected at a camping site the trailer becomes an integral part of a tent 15 which unfolds from within the trailer and is typically fee**: S• connected to the trailer along its upper edge on at least three sides. The trailer itself may provide a platform for one or more sleeping berths. Both two berth and four berth camper trailers are common. A camper trailer is generally less expensive than a caravan and is more versatile as it can be set up virtually anywhere, like a tent, whereas caravans generally must be parked in designated sites.

o. o With the renewed interest in exploring remote wilderness areas, such as may still be found in the centre and north of Australia, there is a need for a heavy duty off-road trailer camper which is capable of traversing unsealed roads and rough terrain such as is only accessible by four wheel drive vehicles. Not only should the trailer camper be capable of traversingsuch terrain without damaging the wheel axles or suspension, but the suspension should provide a sufficiently smooth ride for the trailer camper to avoid damage to the contents of the trailer camper due to vibration and shocks transmitted via the wheels from the ground. Off-road trailer campers and trailers generally are fitted with leaf spring 3 type suspensions. However, leaf springs are expensive and are difficult to fit and replace should they become damaged.

Furthermore with prior art trailers and the like vehicles, alignment of the wheels is difficult and time consuming as each wheel requires individual adjustment to achieve correct alignment.

It will be appreciated that although the following description will be given primarily with reference to a trailing arm coil suspension for a trailer camper, the coil suspension according to the invention may be employed in any trailer or the like vehicle such as a caravan if desired.

SUMMARY OF THE INVENTION *The present invention was developed with a view to providing a trailing arm coil suspension which is simple in construction, and- which facilitates easy wheel alignment.

According to the present invention there is provided a trailing arm coil suspension for a trailer or the like vehicle, the suspension comprising: e* e a mounting member adapted to be fixed transversely of the trailer and having first and second trailing arms pivotally mounted thereon, each trailing arm having a stub axle fitted thereto for supporting a respective wheel of the trailer; and, an elongate alignment member adapted to be anchored at one end to the trailer, the other end of the alignment member being adjustably connected to a mid-point of the mounting member whereby, in use, the tension on said alignment member can be adjusted to simultaneously alter the alignment of both trailer wheels.

Preferably said alignment member is a threaded spindle and 4 the other end of the alignment bolt passes through the mounting member and is adjustably connected thereto by first and second nuts.

Preferably each of said first and second trailing arms comprises a triangular frame, a hollow base member of said triangular frame having first and second bushes at each end for receiving an elongate pivot pin which extends through said base member for pivotally mounting the base member on the mounting member. Typically said mounting member is provided with first and second mounting brackets for each trailing arm, through which said pivot pin passes.

Advantageously said pivot pin is provided with a lock tab at one end for locking the pin to one of said mounting brackets.

In one embodiment said suspension is fitted to an off-road S 15 camper trailer, the camper trailer having a hingedly mounted side panel provided with a shelf thereon, wherein said side panel can be swung out in a horizontal arc when camping to V-09 provide easy access to said shelf without having to unpack 0 the trailer. Advantageously said shelf is adapted to support a camp stove and a camp refrigeration unit thereon so as to form a fold out camp kitchen.

BRIEF DESCRIPTION OF THE DRAWINGS In order to facilitate a better understanding of the nature of the invention a preferred embodiment of the trailing arm coil suspension and a camper trailer with the suspension fitted thereto will now be described in detail, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is an exploded perspective view of one embodiment of the trailing arm coil suspension; Figure 2 is a plan view of the suspension illustrating how the wheel alignment can be adjusted; and, 5 Figure 3 illustrates a preferred embodiment of a camper trailer which incorporates the suspension of Figures 1 and 2.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT An exploded perspective view of a preferred embodiment of the trailing arm coil suspension 10 of the present invention is illustrated in Figure i. The suspension 10 comprises a mounting member 12 adapted to be fixed transversely of the trailer (not illustrated in Figures 1 and In this embodiment, the mounting member is a 75 x 50 x 8mm angle iron beam mounted upright to the underside of the trailer by welding each end to the trailer chassis. Mounting member 12 is provided with first and second trailing arms 14 pivotally mounted thereon, each trailing arm 14 having a stub axle 16 fitted thereto and adapted to support a respective wheel (not 15 illustrated) of the trailer. Advantageously the stub axles 16 are removably mounted on a mounting plate 17 using a plurality of bolts and nuts (not shown) In this way the stub axle can be easily replaced should it become damaged.

For ease of illustration, only one of the trailing arms 14 is illustrated in Figure 1.

Each trailing arm 14 comprises a hollow base member 18 with first and second pivot arms 20 forming a triangular frame.

In the illustrated embodiment the hollow base member 18 is formed by a length of pipe of circular cross section having an outside diameter of 50mm, whereas the first and second pivot arms 20 are formed of rectangular hollow section (RHS) All of the components of the suspension are manufactured from steel. The hollow base member 18 is provided with first and second pivot bushes 22 at each end, each bush 22 having an outside diameter sized to fit snugly within the inside diameter of the base member 18.

The bushes 22 are adapted to receive an elongate pivot pin 24 which extends through the hollow base member 18 for pivotally mounting the base member 18 on the mounting member 12. For 6 this purpose, mounting member 12 is provided with first and second mounting brackets 26,28. Each of the bushes 22 are similar to a standard pivot bush manufactured from a suitable polymer material, of the kind employed in LANDCRUISER motor vehicles. Each bush 22 is provided with an end flange which provides a bearing surface between the end face of the hollow base member 18 and the respective mounting bracket 26,28. Advantageously, the pivot pin 24 is provided with a lock tab 32 at the outer end which can be fixed to the first mounting bracket 26 by means of a small bolt and nut (not illustrated) to retain the pivot pin 24 and hence the trailing arm 14 in its pivoting position in use.

The first and second pivot arms 20 are connected to the :respective ends of the base member 18 immediately adjacent the point of pivotal connection with the respective first and second mounting brackets 26,28, so that any loads transmitted from the stub axle 16 via the pivot arms 20 are transmitted via the bushes 22 and pivot pin 24 directly to the respective mounting brackets 26,28.

o* Each of the trailing arms 14 is provided with a spring bucket 34 adjacent the stub axle 16 and adapted to receive one end of a heavy duty coil spring 36 therein. The other end of the coil spring 36 is located in a spring locater 38 welded to the underside of the trailer chassis (not illustrated). A heavy duty shock absorber 40 is also connected at one end to the trailing arm 14 at a point adjacent the stub axle 16, with the other end connected to the underside of the trailer chassis. The shock absorber 40 may be mounted either to front or rear of the coil spring 36. It will be appreciated that most of the vibration and shocks transmitted via the trailer wheels to the stub axle 16 are absorbed by the coil spring 36 and shock absorber 40. Most of the load carried by the trailer will likewise be transmitted via the coil spring 36, stub axle 16 and the trailer wheel to the ground. Most of the forces acting on the pivot arms 20 of the trailing 7 arms 14 are tensile forces generated by the rolling friction of the wheels on the road surface as the trailer is pulled along by the towing vehicle.

The coil suspension 10 further comprises an elongate alignment member in the form of an alignment bolt 42 adapted to be anchored at one end to a trailer member 44, the other end of the alignment bolt 42 being adjustably connected to a mid point of the mounting member 12. Trailer member 44 in this embodiment is welded to the underside of the trailer chassis at the front end. The other end of the alignment bolt is threaded and passes through an aperture 46 in the mounting member 12 and is adjustably connected thereto by 0first and second nuts 48. By turning the nuts 48 the tension on the alignment bolt 42 can be adjusted to cause a flexing 0 0.

15 of the mounting member 12 as shown in Figure 2. Flexing of the mounting member 12 in the direction of arrows A and B in S• Figure 2 results in a corresponding movement of the trailing arms 14 in the direction of arrows C and D respectively in Figure 2. With this arrangement it will be appreciated that 20 by adjusting the tension on the alignment bolt 42 the alignment of both trailer wheels (not illustrated) provided on stub axle 16 can be altered simultaneously in a simple and ee effective manner. Alignment bolt 42 also stabilises the t mounting member 12 at its mid-point.

oo 25 Now that a preferred embodiment of the trailing arm coil suspension has been described in detail it will be apparent that the described suspension provides a number of advantages over the prior art including but not limited to the following: it is of simple but robust construction and therefore can be manufactured at minimum cost; (ii) the pivotal connection of the trailing arms to the mounting member using a single pivot pin facilitates easy 8 replacement and repair of broken or worn parts; (iii) it can be fitted to any trailer or the like vehicle with minimum modifications to the trailer chassis; (iv) it provides a simple and effective means for wheel alignment of the trailer wheels; and, it is able to provide a smooth ride and stability in rough off-road conditions.

Figure 3 illustrates one embodiment of an off-road camper trailer 50 to which the suspension of Figures 1 and 2 has 10 been fitted (not visible in Figure The camper trailer oooo has a hingedly mounted side panel 52 provided with a shelf 54 thereon. The side panel 52 can be swung out in a horizontal arc to an open position as illustrated in Figure 3, to provide easy access to the shelf 54 without having to unpack 15 the trailer. A catch 56 may be provided on shelf 54 to lock the side panel 52 in the open position. A support post 58 may be removably fitted to the free end of the side panel 52 to provide additional support for the shelf 54 in its open position. Advantageously, the shelf 54 is adapted to support ego* a camp stove and a camp refrigeration unit thereon so as to form a fold out camp kitchen.

The illustrated camper trailer 50 is a four berth trailer having a double bed base provided in the top half of the trailer and an internal storage and bedding area in the bottom half of the trailer. When side panel 52 is in the closed position, shelf 54 and items stored thereon will occupy some of the internal storage space. However, it will be appreciated that when setting up camp the side panel 52 with its built-in shelf 54 provides a very efficient and useful means for unpacking and setting up camp. Side panel 52 can also be opened at any roadside stop or picnic spot so that a kettle can be boiled for tea or coffee and access to 9 food or cool drinks stored in the refrigeration unit is simultaneously provided. A recessed door handle 60 is provided preferably with a key-operated lock to provide added security. The camper trailer 50 is manufactured from galvanised iron.

Now that a preferred embodiment of the trailing arm coil suspension and a camper trailer incorporating same have been described in detail it will be apparent that numerous variations and modifications may be made, in addition to those already described, without departing from the basic inventive concepts. For example, it is not essential that the elongate alignment member be anchored to the front end of the trailer chassis, as it would function equally well anchored to the rear end of the trailer. Furthermore, any 15 suitable means for adjustably connecting the alignment member to the mounting member of the suspension may be employed.

Also the trailing arms need not be of triangular frame construction, although this is the preferred arrangement in view of the inherent strength and rigidity of such a structure. All such variations and modifications are to be considered within the scope of the present invention, the nature of which is to be determined from the foregoing di a description and the appended claims.

oe.o

Claims (8)

1. 2. A trailing arm coil suspension as defined in claim .*Sao: i, wherein said alignment member is a threaded spindle and the other end of the alignment member passes through the mounting member and is adjustably connected thereto by first S: and second nuts.
2. 3. A trailing arm coil suspension as defined in claim 1, wherein each of said first and second trailing arms comprises a triangular frame, a hollow base member of said triangular frame having first and second bushes at each end for receiving an elongate pivot pin which extends through said base member for pivotally mounting the base member on the mounting member.
3. 4. A trailing arm coil suspension as defined in claim 3, wherein said mounting member is provided with first and second mounting brackets for each trailing arm, through which said pivot pin passes. A trailing arm coil suspension as defined in claim 11 3, wherein said pivot pin is provided with a lock tab at one end for locking the pin to one of said mounting brackets.
4. 6. A trailing arm coil suspension as defined in any one of the preceding claims, wherein each trailing arm has the stub axle removably mounted thereon whereby the stub axle can be easily replaced in the event it becomes damaged.
5. 7. An off-road camper trailer having a trailing arm coil suspension as defined in any one of claims 1 to 6.
6. 8. An off-road camper trailer as defined in claim 7, having a hingedly mounted side panel provided with a shelf thereon, wherein said side panel can be swung out in a see: 15 horizontal arc when camping to provide easy access to said :shelf without having to unpack the trailer.
7. 9. An off-road camper trailer as defined in claim 8, wherein said shelf is adapted to support a camp stove and a camp refrigeration unit thereon so as to form a fold out ee* camp kitchen. see ooo A trailing arm coil suspension substantially as herein described with reference to and as illustrated in the 25 accompanying drawings. see
8. 11. An off-road camper trailer substantially as herein described with reference to and as illustrated in the accompanying drawings. Dated this 22 nd day of March 2000 DARRYL JAMES MARTIN By his Patent Attorneys GRIFFITH HACK Fellows Institute of Patent Attorneys of Australia.