GB2468027A

GB2468027A - A suspension unit for a trailer and a self-steering trailer

Info

Publication number: GB2468027A
Application number: GB1002635A
Authority: GB
Inventors: Derrick Bertram Rose
Original assignee: ELIZABETH DAVINA ROSE
Current assignee: ELIZABETH DAVINA ROSE
Priority date: 2009-02-18
Filing date: 2010-02-16
Publication date: 2010-08-25
Anticipated expiration: 2030-02-16
Also published as: GB201002635D0; GB2468027B; GB0902695D0

Abstract

A suspension unit for a trailer or the like is disclosed which includes a rigidly mounted inner member 14 surrounded by elastomeric components 18 enclosed within a rotatable outer housing 12. The outer housing 12 supports a stub axle 16 for resilient movement about a central axis A. In an alternative the stub axle may be mounted perpendicular to the axis A. A self-steering trailer is also disclosed which may employ the above-mentioned suspension.

Description

Improvements in and relating to a trailer and trailer suspension This invention relates to a trailer suspension and a steerable trailer.

A common form of trailer or caravan suspension is known as a rubber torsion suspension in which an inner rotatable shaft is held within a static outer housing mounted to the chassis of the trailer or caravan. The inner shaft is substantially surrounded by rubber formations which allow the inner shaft to rotate resiliently due to compression of the rubber formations, and which urge the inner shaft to react against forces pushing on the suspension, for example a wheel mounted on a trailing arm, in turn mounted to the inner shaft.

In the common arrangement of an axle mounted on a trailing arm of these known suspensions, the inner shaft will, with age and wear, become loose, and forces exerted on the trailing arm cause bending moments on the inner shaft.

These moments eventually lead to significant wear on the rubber parts. With these known arrangements it is difficult to captivate the inner shaft and with age and wear lateral movement can occur which will eventually lead to wheel misalignment and possibly detachment of the inner shaft from its outer static housing. Figures 1 and 2 illustrate known suspension units. *..

According to a first aspect, the present invention provides a resilient

SS * S

*. : wheel suspension unit comprising an inner support member rigidly attached or * *20 attachable to a trailer chassis or the like and extending along an axis which is * *:*::* generally horizontal in use, one or more elastomeric bodies disposed generally radially outwardly of the inner support member and an outer member rotatable about said axis disposed generally radially outwardly of said elastomeric formations and being adapted for resilient rotation about said axis.

In an embodiment the outer member is rigidly connected to a wheel support, and preferably said wheel support includes a stub axle.

In an embodiment the wheel support is a trailing arm.

Preferably said inner member is straight sided in a section perpendicular to said axis and preferably said outer member has straight sided formations facing said inner member.

Preferably the outer and inner members are tubular in section and preferably said tubes are square.

In an embodiment the wheel support or trailing arm is welded to the outer member and said weld extends at least in a direction parallel to said axis.

Preferably said wheel support or trailing arm comprises at least two arm members each of which is welded to said outer member.

In an embodiment said stub axle is moveable in a direction parallel to said axis.

Alternatively, said axle is arranged such that its suspension movement is radial about said axis.

In a further embodiment said inner member is elongate and two or more said outer members, individually rotatable about said axis are mounted to the * S *. elongate inner member.

* ,20 According to a second aspect, the present invention provides a simple

S

*:*::* and robust arrangement for a self steering trailer having at least one pair of wheels, the invention consisting in a trailer having a frame, at least one pair of *S..*. * *

wheels and a drawbar, the drawbar being pivotable on the frame about a vertical pivot, the wheels and drawbar being in communication such that movement of the drawbar in one direction causes each of the wheels to steer in the same direction.

Preferably, the wheels rotate about an axis and the pivot is at the axis.

In an embodiment, the drawbar is operatively connected to a steering rod behind the pivot, to transmit motion to the wheels.

Preferably the trailer includes wheel suspension units according to the first aspect.

Preferably tie rods are provided to hold said wheels in alignment.

The aspects of the invention can be put into effect in numerous ways, one embodiment only being described with reference to the drawings wherein: Figures 1 and 2 show a conventional rubber torsion suspension: Figures 3, 4, 5 and 6 show a suspension according to the invention; Figures 7, 8 and 9 show a further suspension according to the invention; and Figures 10 and 11 show plan and side views of a self steering trailer incorporating a suspension according to the invention.

Figures 1 and 2 show a known trailer suspension unit 1. The unit consists of an outer member 2 rigidly connected to a mounting plate 3. An inner * *S *O* * * member 4 is mounted by means of rubber elements 8 within the outer body 2.

The inner member 4 is rotatable about an axis A. A trailing arm 5 is attached to S..

*:*::* the end of the inner member 4, and a stub axle 6 is in turn attached to the * trailing arm 5. The stub axle 6 supports a wheel hub 7 which, in use, is * . resiliently supported for occasional movement about the axis A by means of compression or stretching of the rubber bodies within the outer member 2.

In this arrangement the trailing arm 5 can be mounted only at one end of the inner member 4 and suspension forces exerted through the stub axle 6 cause bending moments on the inner member 4 which are undesirable.

Figures 3, 4, 5 and 6 show a trailer suspension unit according to the invention. With reference to those Figures a wheel hub 17 is supported on a stub axle 16. The stub axle is in turn supported by two plates 15 welded to the stub axle 16. At their inboard ends these plates 15 are in turn welded to an outer member 12. The outer member 12 is resiliently rotatable generally about an axis A. The outer member 12 is mounted around an inner beam 14 which in turn is rigidly mounted to the chassis 13 of the trailer.

Additionally referring to Figure 4, this Figure shows a section through the suspension shown in Figure 3 along the line I-I. The inner beam 14 is visible showing a generally square section and being rigidly mountable to the chassis 13. Surrounding the beam 14 is the outer housing 12, which in this case is also a square section offset to the square section of the beam 14. In the triangular gaps left by the offset positions of the inner beam 14 and the outer member 12 are disposed elastomeric bodies 18. In practice these elastomeric bodies are *s..

compressed into their triangular shape shown, from a generally circular section.

S..... * .

Since they are in a pre-compressed state, they urge the outer member 12 into *20 the neutral position shown in Figure 4. When suspension loads are exerted on ***

I

the stub axle 16 the rubber bodies 18 are compressed and react those suspension loads. Thus, the stub axle 16 is supported resiliently and is urged into the position shown in Figure 4 when forces on the stub axle 16 urge the rotation about the axis A. The plates 15 are welded to the outer member 12 at opposed corners of the square section, providing spaced support for the axle 16 and thereby a more rigid mounting for the axle 16. Beam 14 is a single length of material which has an opposite end for mounting any further trailer suspension unit 10 (not shown) which is a mirror image of the mounting shown in Figure 3.

Figures 5 and 6 show further views of the trailer mounting illustrated in Figures 3 and 4. Figure 5 is a plan view of a near-side unit, whereas Figure 6 is a view from a forward direction of an off-side unit, which is otherwise the same as the unit shown in Figure 5.

The trailer suspension 20 illustrated in Figures 7, 8 and 9 show a modified trailer suspension according to the invention. In this arrangement, an outer member 22 is arranged around an inner member 24, and is spaced therefrom by means of elastomeric bádies 28, in a similar manner to the suspension unit 10, described above. The outer member 22 carries a braced support 25 and a stub axle 26. The stub axle 26 carries a wheel hub 27. In this arrangement the stub axle 26 is not mounted with an axis parallel to the axis A of the movement of the suspension unit, but is mounted perpendicular thereto, such that a wheel *S..

mounted to the wheel hub 27 will move in an arc R about the suspension axis A. a.....

* In this embodiment there are two wheel hubs 27 mounted in parallel on an inner *.20 member 24. The inner member 24 is mounted to a trailer chassis 23. In order *** to make alignment of the wheels easier, the inner member 24 is rigidly attached a:.::: to a cross-beam 29. The cross-beam 29 will have a similar suspension *.. .*.

* arrangement at its opposite end (not shown) and that arrangement will be a mirror image of the suspension shown in Figures 7, 8 and 9.

It will be appreciated that the arrangement mentioned immediately above could be employed with just one wheel axle, or more than the two axles shown.

Figures 10 and 11 show plan and rear views respectively of a trailer chassis which includes a self steering arrangement. Although not essential, the arrangement shown could employ a suspension unit similar to those described above.

Figure 10 shows a drawbar 35 for a trailer which is pivotally mounted to a trailer chassis 33 at a pivot pin 31 Side loads exerted on the drawbar 35 in the direction of arrows X will cause the drawbar to pivot. The drawbar is further connected to a steering rod linkage 32 which causes wheel hubs 37 to rotate about king pins, so as to steer wheels connected to those hubs in the same direction as the force on the drawbar 35. The drawbar 35, during rotation, abuts stops 38 mounted to the steering rod linkage 32. It will be noted that the draw bar is not rigidly connect to the steering rod linkage 32, but rather the linkage an move up and down independently of the drawbar, to travel with the suspension.

Ball joints on each end of the steering Image 32 allow independent travel of each nearside/offside suspension without affecting the steering. Further, axle beam *S.* 42 is pivotally mounted on the chassis 33 so that it can rotate generally about an S.....

* axis running between the two hubs 37. The drawbar 35 is mounted to the beam 42 via pivot 31, so that the drawbar too can move up and down (in a direction *.* into and out of the paper). This up and down movement of drawbar 35 is limited * S* by chassis members (not shown).

S.....

* In this embodiment, suspension units 30 support the hubs 37. The suspension units 30 are similar to the suspension unit shown in Figure 8, but just one wheel hub is supported for radial movement during suspension, not a pair as shown in Figure 7. The wheel hub 37 is further supported by means of tie rods 34 which assist in holding the wheel hubs 37 in position. The tie rods 34 are pivotally mounted at their inboard ends and include a sliding mechanism 40 at their outboard ends, in this case a rod attached to the tie rod is slideable in an aperture in a component attached to the radial arm of the suspension. This tie rod arrangement can be used too for lateral (front to back) support for the suspension arrangement shown in Figures 7,8 and 9. It will be apparent that the tie rod arrangement shown could be mounted under the chassis 33. More than one axle can be steered using this arrangement. Where more than one axle is steered the drawbar can be linked, for example mechanically linked, to each wheel pair by additional steering linkages, similar to the linkage 32, each connected to the drawbar. In practice, an addition mirror image of the mechanism shown can be used, in front of the vertical pivot 31, which can be used to steer a further set of wheels in front of the pair of hubs 37 illustrated. In that case the pivot point 31 will be half way between the notional lines joining respective centres of rotation of the axles of the then forward and rear hubs. *..*

In an alternative embodiment, the steering linkage 32 can be located * forward of the pivot 31, to steer the hubs 37 from the front.

Whilst the invention has been described with reference to trailers and the S..

like, it will be appreciated that this term will encompass any item towed by a * ..

vehicle, such as a trailer, caravan, or car towing apparatus. Further, the * suspension described need not be limited to use on trailers. It is generally envisaged that the components mentioned above, other than the elastomeric components, will be formed from steel, although other materials could be used, * for example aluminium or plastics material. The hubs 17, 27 and 37 are intended to support conventional wheels and pneumatic tyres although the term wheel is to be interpreted broadly to include other ground engaging members, for example skids or solid tyres. * * **** *

****** * * ** * * * * * ** *

S * S. * S * * ..

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Claims

Claims 1 A resilient wheel suspension unit comprising an inner support member rigidly attached or attachable to a trailer chassis or the like and extending along an axis which is generally horizontal in use, one or more elastomeric bodies disposed generally radially outwardly of the inner support member and an outer member rotatable about said axis disposed generally radially outwardly of said elastomeric formations and being adapted for resilient rotation about said axis.
2. A suspension unit as claimed in claim 1, wherein the outer member is rigidly connected to a wheel support, and preferably said wheel support includes a stub axle.
3. A suspension unit as claimed in claim 2, wherein the wheel support is a trailing arm.
4. A suspension unit as claimed in claim 2 or 3, wherein said inner member is straight sided in a section perpendicular to said axis and preferably said outer member has straight sided formations facing said inner member.
5. A suspension unit as claimed in any one of the preceding claims, wherein the outer and inner members are tubular in section and preferably said tubes are *S.. * .square. *

* ***** *
6. A suspension unit as claimed in claim 2, 3 or 4 or 5, wherein the wheel support or trailing arm is welded to the outer member and said weld extends at least in a direction parallel to said axis. * **
7. Asuspension unit as claimed in any one of the preceding claims 2 to 5, * wherein said wheel support or trailing arm comprises at least two arm members each of which is welded to said outer member.
8. A suspension unit as claimed in any one of the preceding claims, wherein a stub axle is connected to said outer member for movement therewith and has its own axis.
9. A suspension unit as claimed in claim 8, wherein said movement of said stub axle axis is in a direction parallel to said suspension axis in use.
10. A suspension unit as claimed claim 8 wherein, said movement of said stub axle axis is is radial about said suspension axis in use.
11. A suspension unit as claimed in any one of the preceding claims, wherein said inner member is elongate and two or more said outer members are mounted to the elongate inner member for independent rotation about said suspension axis.
12. A self steering trailer having a frame, at least one pair of side by side wheels and a drawbar, the drawbar being pivotable on the frame about a vertical pivot, the wheels and drawbar being in communication such that movement of the drawbar in one direction causes each of the wheels to steer in the same direction.
13. A trailer as claimed in claim 12, wherein the wheels when aligned rotate about a common wheel axis, and the axis of the pivot substantially intersects S.....* the wheel axis.*..:2O
14. A trailer as claimed in claim 12 or 13, wherein the drawbar is operatively connected to a steering rod behind the pivot, to transmit steering motion to the * .. * S ** . wheels.

S.....

*
15. A trailer as claimed in claim 12 or 13, wherein the drawbar is operatively connected to a steering rod in front of the pivot, to transmit steering motion to the wheels.
16. A trailer as claimed in any one of the preceding claims 12 to 15, wherein the trailer further includes wheel suspension units according to any one of claims Itoh.
17. A trailer as claimed in any one of claims 12 to 16, wherein tie rods are provided to hold said wheels in alignment.
18. A trailer as claimed in claim 12, wherein the trailer includes two pairs of steerable wheels and the drawbar is pivotable to move both pairs in the same direction, the rearward pair being moved by a steering linkage located behind the pivot connecting the rearward pair to the drawbar, and the forward pair being moved by a steering linkage located in front of the pivot connecting the foreward pair to the drawbar.
19. A trailer suspension or self steering trailer as described herein optionally with reference to the drawings. S... * S *S*.S * S *S S * . . * S.S 55.S * S* * S * * *S* S5S.5S