AU2007201908A1

AU2007201908A1 - Trailer suspension

Info

Publication number: AU2007201908A1
Application number: AU2007201908A
Authority: AU
Inventors: Gary Borchert
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-04-30
Filing date: 2007-04-30
Publication date: 2008-11-13

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION Standard Patent Applicant(s): Gary Borchert Invention Title: TRAILER SUSPENSION The following statement is a full description of this invention, including the best method for performing it known to me/us: 2 C TRAILER SUSPENSION Field of the Invention O This invention relates to a trailer suspension.

00Background of the Invention Suspensions for trailers generally comprise conventional leaf spring suspensions which support one or more axles of C the trailer. These conventional suspension systems do provide a degree of shock absorbance when the trailer Straverses uneven ground. However, conventional systems do not provide for even distribution of weight over the load bearing area of the trailer nor prevent front drawbar down force. Furthermore, the nature of the shock absorption is somewhat limited. Thus, conventional trailers supported on conventional suspension systems do tend to tilt or move in unacceptable ways because of uneven load distribution, and when the trailer is towed over uneven ground. This therefore effects the ability to safely carry loads and also enable safe towing of the trailer behind a vehicle.

Summary of the Invention The object of the invention is to provide a trailer suspension which overcomes these problems.

The present invention provides a trailer suspension for a trailer having at least one axle, and a trailer chassis, and a drawbar, comprising: a suspension unit adjacent each end of the at least one axle for coupling the at least one axle to the chassis; a first link arm extending between the at least one axle and the trailer chassis; a yoke and a universal joint for connecting the link arm to at least one of the chassis and the at least one axle; and wherein the at least one axle is able to rotate H.\Luisal\Keep\Speci\Borchert Trailer Suspension.doc 27/04/07 3 v about a longitudinal axis of the axle and about an axis Sperpendicular to the longitudinal axis of the axle.

O Thus, the trailer suspension enables loads to be evenly distributed over the chassis because of the manner in which the axle can rotate and also takes up shock as the 00 trailer traverses uneven ground, thereby improving weight distribution over the load bearing area of the trailer, C ease of towing the trailer, and prevents down forces on the drawbar of the trailer, thereby greatly improving towing performance of the trailer.

Preferably each suspension unit comprises: a support member; a second universal joint between the support member and the axle for connecting the support member to the axle; at least one coil spring extending between the support member and the chassis of the trailer; and at least one damper extending between the support member and the chassis of the trailer.

Preferably each suspension unit comprises two coil springs and two dampers with a respective coil spring being located around a respective damper.

Preferably the support member comprises a support plate.

Preferably the first link arm is rigidly fixed to the at least one axle and the universal joint and the yoke connects the first link arm to the chassis of the trailer.

Preferably the yoke comprises a hole in the chassis and a pin for location in the hole to thereby enable the link arm to rotate about the perpendicular axis because of location of the pin in the hole, and wherein the pin is able to move into and out of the hole when the universal H:\Luisal\Keep\Speci\Borchert Trailer Suspension.doc 27/04/07 4 joint moves with movement of the first link arm.

In one embodiment of the invention the trailer has O multiple axles, each axle having a said suspension unit adjacent each end of each axle, and plural link arms, each link arm having a universal joint and a yoke for 00 connecting the link arm to the chassis or an adjacent axle so that each axle is able to undergo rotation about its C longitudinal axis and rotation about the perpendicular axis.

In one embodiment of the invention the trailer further comprises a second axle, and the trailer suspension further comprises a second link arm extending between the said at least one axle and the second axle, a second universal joint and yoke coupling one end of the second link arm to one of the axles, and a third universal joint and yoke between the second axle and the chassis, a suspension unit adjacent each end of the second axle for connecting the second axle to the chassis, and wherein the second axle is able to undergo rotation about its longitudinal axis and also about an axis perpendicular to the second axle.

Preferably the other end of the second link arm is fixed to the other axle.

Preferably the or each axle comprises stub axles and the end of the or each axle for mounting a wheel for rotation the stub axles.

Preferably each wheel has a disc brake.

Preferably trailing arms are pivotally connected to the chassis and to the or each axle.

The invention also provides a trailer having the above- H,\Luieal\Keep\Speci\Borchert Trailer Suspenelon.doc 27/04/07 5 mentioned trailer suspension.

Brief Description of the Drawings O A preferred embodiment of the invention will be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is a plan view of a trailer chassis and trailer suspension according to the preferred embodiment C of the invention; Figure 2 is a cross-sectional view along the line II-II of Figure 1; Figure 3 is a side view of the trailer chassis and suspension of Figure 1; Figure 4 is a rear view of the trailer chassis and suspension; Figures 5 and 6 are drawings illustrating movement provided by the suspension system of the preferred embodiment; Figures 7 and 8 are views of the suspension in operation as the trailer traverses uneven ground; Figure 9 is a detailed view of a yoke used in the preferred embodiment of the invention; Figures 10, 11 and 12 are drawings showing different suspension unit positions which are taken up as the trailer traverses uneven ground or when load is distributed on the trailer; Figures 13 and 14 are diagrams showing the position of an axle relative to the suspension unit during movement of the suspension system; and Figure 15 is a perspective view of a trailer chassis used with one embodiment of the invention.

Detailed Description of the Preferred Embodiment With reference to Figure 1 a trailer chassis and suspension unit is shown. The trailer chassis comprises side rails 12 and 14 which are formed from angle iron and which are joined by cross frame members 16, 18, H \Luisal\Keep\Speci\Borchert Trailer Suspension.doc 27/04/07 6 and 22. Support rails 24 and 26 are arranged inwardly of Sthe rails 12 and 14 and extend between the cross frame members 18 and 22. As shown in Figure 4, a stem 27 extends downwardly from a mid-portion of the cross frame member 22 and struts 28 are located between the lower portion of the stem 27 and the respective ends of the cross frame member 22.

C As shown in Figure 2, the front of the chassis 10 also has a stem 27' which is the same as the stem 27 and struts 28' (Figure 15) extend from the bottom of the stem 27' to the ends of cross frame member 16 in the same configuration as the struts 28 shown in Figure 4.

A drawbar 30 is connected to the chassis 10 such as to the bottom of stem 27' to enable the trailer chassis 10 to be towed behind a vehicle.

A trailer body (not shown) can be received on the chassis 10 between the rails 12 and 14 by sliding the body into position and then securing the body to the chassis Thus, if desired, bodies can be interchanged so that the trailer can carry different body configurations depending on the intended use of the trailer and the load the trailer is intended to carry.

In the embodiment shown in the drawings, the trailer is a tandem axle trailer. However, the invention is applicable to single axle trailers, tri-axle trailers and quad-axle trailers, etc.

A front axle 32 and a rear axle 34 are attached to the chassis 10 and supported to the chassis 10 by suspension units 36. The suspension units 36 are all the same and, as best shown in Figure 2, comprise a bottom plate 38 on which is supported first and second dampers 40 and 41.

The dampers 40 and 41 have arms 42 which are bolted to H:\Luisal\Keep\Speci\Rorchert Trailer Suspension.doc 27/04/07 7 rails 24 and 26 by bolts 43 (see Figure A coil spring S44 is provided around the damper 40 and a coil spring 46 is provided around the damper 41. The coil springs extend between the plate 38 and the rail 24 (or 26 as the case may be). The springs 44 and 46 may be secured to the plate 38 and to the rail 24 (or 26).

Each plate 38 is connected to its respective axle 32 or 34 Sby a universal joint 48. As best shown in Figure 1, the axle 32 has two stub axles 49 on which is mounted a wheel which in turn mounts a tyre 52 as is conventional. The wheel 50 has a disc brake system formed from a disc 51 and calliper 53 which is also conventional. The rear axle 34 also has stub axles 49, wheels 50, tyres 52 and a disc 51 and calliper 53.

As is best shown in Figures 1 and 2, a first link arm extends between the stem 27' and the front axle 32. The link arm 50 has one end welded to the axle 32 and the other end is connected to the stem 27' by a universal joint 61 and a yoke 63.

As is best shown in Figure 9, the yoke 63 comprises a hole 64 in the stem 27' in which is located a bush 65. The yoke 63 also has a pin 66 which is connected to the universal joint 61 and is received in the bush 65 so the arm 60 and universal joint 61 can rotate about longitudinal axis L of the arm 60 relative to the stem 26'. Thus, axle 32 can rotate about an axis perpendicular to the axis of the axle 32 as shown in Figures 5 and 6.

The pin 66 is also able to move slightly inwardly or outwardly of the hole 64 in the bush An intermediate link arm 70 has one end welded to the rear axle 34 and the other end is connected to the front axle 32 by a universal joint 71 and a yoke 72 which is identical to the yoke 63 previously described. A double H4\Luiaal\Kee\Speci\Borchert Trailer Suepenaiondoc 27/04/07 8 universal joint 78 and a yoke 79 is attached between the Saxle 34 and stem 27. The double universal joint 78 comprises two universal joints welded together in back to back relationship, and the yoke 79 is also the same as the yoke 63 previously described.

00 Front trailing arms 80 are pivotally connected to axle 32 and respective rails 12 and 14 by pivot connections 87 and 88. Rear trailing arms 90 are pivotally connected to rear axle 34 and rails 12 and 14 by pivot connections 90 and 91. The trailer suspension described above therefore enables the axle 32 to rotate slightly about its longitudinal axis with that relative rotation being accommodated by the universal joint 48 which connects the axle 32 to the plate 38 of the suspension units 36 associated with the axle 32. The rotation is also accommodated by the universal joint 61 and movement of the pin 66 of the yoke 63 into and out of the hole 64.

Furtherstill, the plate 38 is able to move depending on the compression of the springs 44 and 46 and the damping of the dampers 40 and 41 whilst the axle 32 remains stationary as is best shown in Figures 10, 11 and 12.

Furtherstill, the movement the trailer suspension is able to undergo can be a combination of all the separate movements referred to above.

Yoke 72 and universal joint 71 also accommodate the rotational movement of the axle 32 by the pin 66 of the yoke 72 moving into and out of its respective hole 64.

The axle 34 is able to rotate in the same manner with the rotation being accommodated by the universal joints 48 in the same manner previously described, and by the yoke 72 and universal joint 71 and the double universal joint 78 and yoke 79.

Furtherstill, the axles 32 are able to rotate about the H:\Luisal\Keep\Speci\Borchert Trailer Suspension.doc 27/04/07 9 longitudinal axis of the link arms 60 and 70 as is best Sshown in Figures 5 and 6, because of the yokes 63, 72 and 79 and the respective pin 66 of those yokes enabling rotation around the axis L (see Figure 9) in the manner previously described. The axis L is the axis of the link arms 60 and 70 (and the joint 78) and is also 00 perpendicular to the longitudinal axis of the axles 32 and 34. This relative movement is shown in Figures 5 and 6 C between the position of the axle 32 shown in solid lines and the position 32' in dash lines. The axle 34 is able to undergo independent movement in the same manner as that shown in Figures 5 and 6.

The trailer suspension described above which is able to undergo the various types of movements referred to above thereby enables even distribution of weight over the entire load bearing area of the chassis 10 and also prevents down forces on the drawbar As the trailer moves over uneven ground, as is best shown in Figure 7, the tyres 51 are able to move up and down with their respective axles 32 and 34 with the up and downward movement being accommodated by the universal joint 48 and the universal joints 61, 71 and 78, together with the respective yokes 63, 72 and 79.

As is best shown in Figure 7, the tyre labelled 52 is riding over rough ground and this causes a slight rotation of the axle 32 which in turn is accommodated by the universal joint 71 and slightly outward movement of the pin 66 of the yoke 72 so that the link arm 70 takes a slightly inclined position, thereby rotating axle 34. The rotation of the axle 34 is also accommodated by its universal joints 48 and the double universal joint 78 and movement of the pin 66 of the yoke 79 slightly out of its hole 64. The movement of the axle 32 also causes a slight downward incline of the link arm 60 from the axle 32 which H:\Luisaa\Keep\Speci\Borchert Trailer Suspension.doc 27/04/07 10 Sis accommodated by the universal joint 61 and movement of Sthe pin 66 of the universal joint 63 further into its hole 64.

If only one of the tyres 52 of the axle 32 is moving over rough terrain, then the axle 32 is able to rotate about 00 0the longitudinal axis of the links 60 and 70 by rotation of the respective pin 66 of the yokes 63, 72 and 79 in Stheir respective holes 64. As shown in Figures 13 and 14, the springs 44 and 46 remain in the same orientation when the axles 32 and 34 rotate.

Figure 8 shows the rear tyre 52 travelling over rough terrain with the axle 34 rotating slightly and therefore pushing the pin 66 of the yoke 79 further into its hole 64 and with the movement of the axle 34 being accommodated by the double universal joint 78. The opposite end of the link arm 70 accommodates the rotation of the axle 34 by the universal joint 71 and the yoke 72. In this configuration the link arm 60 may remain in its equilibrium position because the axle 32 has not moved.

However, any rotation of the axle 32 is taken up by the universal joint 61 and the yoke 63.

Furtherstill, any rotational movement of the axles 32 and 34 is also accommodated by the pivotal connection of the trailing arms 80 and 90 via the respective pivot connections 87 and 88 and 90 and 91.

The trailer suspension of the preferred embodiment of the invention therefore enables even distribution of the weight of the load on the chassis over the entire chassis, and prevents down forces on the draw bar 30, thereby making the trailer much easier and safer to tow. If the trailer does sustain a flat tyre, weight is redistributed over the other wheels, preventing pressure on the deflated tyre. Under maximum load conditions, full axle travel can H:\Luial\Keep\Speci\Borchert Trailer Suspension.doc 27/04/07 11 still be achieved without depressing the springs any Sfurther. The use of coil springs in the suspension units 36 delivers a much smoother action and also absorbs roadway shock much better, thereby preventing stress fractures.

00 0The preferred embodiment of the invention has application to any towed vehicles such as caravans, load transporting trailers, horse floats. The preferred embodiment has particular application to the transportation of precious or fragile cargo, such as glass sheeting, because of the improved handling characteristics of the trailer and load distribution as well as shock absorption.

The suspension system of the preferred embodiment of the invention is superior to conventional systems having conventional axles because the axles of the preferred embodiment do not bend at their centres when heavy loads are applied. Each axle is supported at its middle by a yoke and link arm, as previously described, providing more rigidity and support than conventional axles through the entire length of the axle, to each suspension point. This equally divides the load bearing area along the axle.

In conventional suspensions, the midpoint of each set of leaf springs along the axle is under constant stress and causes downward bowing under load condition. The suspension system of the preferred embodiment prevents this common stress point and downward bowing by increasing the rigidity of the axle beam. This rigidity is achieved by welding a central support made up by one link arm onto the centre of the axle which halves the distance between the suspension units. Thus, central bowing of the axle is not possible. Furthermore, the load bearing forces are concentrated to the suspension units preventing misalignment of the trailer wheels. The tyre face of the wheels will therefore remain true to the road surface.

H.\Luisal\Keep\Speci\Borchert Trailer Suspension.doc 27/04/07 12 This significantly reduces the risk of jack-knife Smovements of the trailer, or sliding etc.

Furthermore, the articulated suspension system of the preferred embodiment makes it easier to load the trailer because the trailer can be moved into a desired loading 00 position without the need for a jockey wheel and easily _returned to an orientation for connection of the drawbar to a vehicle. This is because the load is distributed over the trailer and is not concentrated at, for example, Sthe drawbar which makes the drawbar very difficult, if not impossible, to lift if heavy loads are applied to the trailer.

Since modifications within the spirit and scope of the invention may readily be effected by persons skilled within the art, it is to be understood that this invention is not limited to the particular embodiment described by way of example hereinabove.

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise", or variations such as "comprises" or "comprising", is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

H.\Luiaa1\Keep\Speci\Borchert Trailer Suspension.doc 27/04/07

Claims

1. A trailer suspension for a trailer having at least one axle, and a trailer chassis, and a drawbar, comprising: a suspension unit adjacent each end of the at 00 0least one axle for coupling the at least one axle to the chassis; C a first link arm extending between the at least one axle and the trailer chassis; Sa yoke and a universal joint for connecting the link arm to at least one of the chassis and the at least one axle; and wherein the at least one axle is able to rotate about a longitudinal axis of the axle and about an axis perpendicular to the longitudinal axis of the axle.

2. The suspension of claim 1 wherein each suspension unit comprises: a support member; a second universal joint between the support member and the axle for connecting the support member to the axle; at least one coil spring extending between the support member and the chassis of the trailer; and at least one damper extending between the support member and the chassis of the trailer.

3. The suspension of claim 2 wherein each suspension unit comprises two coil springs and two dampers with a respective coil spring being located around a respective damper.

4. The suspension of claim 2 or 3 wherein the support member comprises a support plate.

The suspension of any one of claims 1 to 4 H\Luial\Keep\Speci\Borchert Trailer Suspensiondoc 27/04/07 I -14- Ci wherein the first link arm is rigidly fixed to the at least one axle and the universal joint and the yoke connects the first link arm to the chassis of the trailer.

6. The suspension of any one of claims 1 to 00 wherein the yoke comprises a hole in the chassis and a pin Sfor location in the hole to thereby enable the link arm to rotate about the perpendicular axis because of location of C the pin in the hole, and wherein the pin is able to move into and out of the hole when the universal joint moves Swith movement of the first link arm.

7. The suspension of claim 1 wherein the trailer has multiple axles, each axle having a said suspension unit adjacent each end of each axle, and plural link arms, each link arm having a universal joint and a yoke for connecting the link arm to the chassis or an adjacent axle so that each axle is able to undergo rotation about its longitudinal axis and rotation about the perpendicular axis.

8. The suspension of claim 1 wherein the trailer further comprises a second axle, and the trailer suspension further comprises a second link arm extending between the said at least one axle and the second axle, a second universal joint and yoke coupling one end of the second link arm to one of the axles, and a third universal joint and yoke between the second axle and the chassis, a suspension unit adjacent each end of the second axle for connecting the second axle to the chassis, and wherein the second axle is able to undergo rotation about its longitudinal axis and also about an axis perpendicular to the second axle.

9. The suspension of claim 8 wherein the other end of the second link arm is fixed to the other axle. H:\Luial\Keep\Speci\Borchert Trailer Suspenion.doc 27/04/07 15 C-

10. The suspension of any one of claims 1 to 9 wherein the or each axle comprises stub axles and the end of the or each axle for mounting a wheel for rotation the stub axles. 0

11. The suspension of any one of claims 1 to Swherein each wheel has a disc brake. C-

12. The suspension of any one of claims 1 to 11 wherein trailing arms are pivotally connected to the Schassis and to the or each axle.

13. A trailer having the trailer suspension according to any one of claims 1 to 12. H:\Luisal\Keep\Speci\Borchert Trailer Suspension.doc 27/04/07