GB2032049A

GB2032049A - Suspension unit with removable housing wall

Info

Publication number: GB2032049A
Application number: GB7841786A
Authority: GB
Original assignee: AJC TRAILERS Ltd
Current assignee: AJC TRAILERS Ltd
Priority date: 1978-10-24
Filing date: 1978-10-24
Publication date: 1980-04-30

Abstract

A suspension unit for a light trailer comprises a square rod 5 to which is secured an arm 12 which carries a stub axle 3. The rod 5 is located within a square cavity 10 defined within a housing assembly 2 which is secured to the trailer body. Elastomeric rods 11 are located in the triangular spaces defined between the rod 5 and the walls of the cavity 10 to provide a resistance to rotation of the rod 5 relative to the housing assembly 2. One wall 6 of the housing assembly is removable to allow for inspection and replacement of the elastomeric rods 11. <IMAGE>

Description

SPECIFICATION Suspension unit This invention relates to a suspension unit for mounting a ground engaging wheel on a vehicle.

The described suspension unit is particularly suitable for use on a two-wheeled trailer to be towed by a motor car.

Known suspension units, suitable for use on such trailers, employing resilient elastomeric packing rubbers to provide the desired suspension characteristics have suffered from the disadvantage that, once assembled, the units cannot readily be dis-assembled or re-assembled since such dis-assembly and re-assembly necessitates the use of specialist power presses which are not readily available. This has meant that with such units it is virtually impossible for the owner of a trailer, or even a trailer specialist with a normally equipped workshop to replace the packing rubbers in a suspension unit. Such replacement would be desirable in order to service the unit to replace worn components and in order to change the suspension characteristics of the suspension unit.

According to one feature of the present invention there is provided a suspension unit comprising an elongate hollow non-circular housing assembly which, in use, is secured to a body to be supported by the suspension unit; an elongate non-circular rod located in the housing assembly; a plurality of packing rubbers located between the housing assembly and the rod for resiliently yieldably resisting relative rotation of the rod and the housing; an arm extending radially outwardly from one end of the rod; and an axle extending parallel to the longitudinal axis of the rod secured to the arm at a point spaced from the rod, wherein the housing assembly includes a removable side member secured in position by clamping members, the clamping members being releasable to permit removal of the side member, the packing rubbers and the rod from the remainder of the housing assembly, and being tightenable during re-assembly of the unit to compressably preload the packing rubbers.

With an embodiment of the invention the suspension unit can be completely dis-assembled simply by releasing the clamping members which may be of any convenient form, for example screws and nuts. Once the side member has been removed the packing rubbers can be replaced and the unit re-assembled by progressively tightening the clamping members to provide the desired amount of preload to the packing rubbers.

The above and further features and advantages of the invention will become clear from the following description of an embodiment thereof, given by way of example only, reference being made to the accompanying drawings, wherein: FIGURE 1 is an elevational view of an embodiment of trailer suspension unit; FIGURE 2 is a plan view of the unit of Figure 1; FIGURE 3 is an end view of the unit of Figures 1 and 2; and FIGURE 4 is an exploded perspective view of the unit of Figures 1-3.

The suspension unit 1 shown in Figures 1-3 is one of a pair of handed units suitable for supporting a trailer body on to ground engaging wheels. The trailer body is secured to a housing assembly 2 of the unit and a wheel is rotatably mounted by means of suitable bearings on a stub axle 3 secured at one end of an arm 4 which extends radially outwardly from a rod 5 located within the housing assembly 2.

The housing assembly 2 comprises a flat plate 6 secured to an inverted top-hat section channel member 7 by means of screws 8 and nuts 9. The plate 6 and channel member 7 together define an elongate square-section cavity 10 which extends along the entire length of the housing assembly 2.

As best can be seen from Figure 4, the rod 5 is square in transverse cross section and in the normal un-loaded position of the suspension unit as illustrated in the drawings is located displaced 450 from the square cavity 10. The diagonal dimension of the rod 5 is slightly less than the distance between each pair of parallel sides of the cavity 10 so that in the position illustrated in the drawings there is a small working clearance between the rod 5 and the walls of the cavity.

A packing rubber 11 is located in each of the four generally triangular spaces defined between the rod 5 and the cavity 1 0. The rubbers in their unstressed state are circular in transverse cross section and are of hard rubber. The exact characteristics of the rubber will be determined by the desired suspension load rating and "softness." However, by way of example it has been found that 12 mm neoprene is satisfactory.

During assembly of the suspension unit the packing rubbers 11 and rod 5 are located in the channel member 7 and the plate 6 is secured in position by progressively tightening the nuts 9.

The progressive tightening of the nuts compresses the packing rubbers to provide a desired preload to the suspension unit. Once the nuts have been fully tightened so that the plate 6 seats on the flanges of the channel member 7 the rod 5 will be held in the cavity 10 restrained against rotation relative to the cavity. However, relative rotation of the rod 5 and the housing assembly 2 is possible to a limited extent, and such rotation will result in further compression of the packing rubbers. When the torsional forces on the rod are released the rod will return to its original position as illustrated in the drawings.

The arm 4 is advantageously fabricated from two channel section members 12, 13 nested one within the other and welded together to form a single composite member. During pressing of the channel section members 12, 1 3 each is formed with a square hole and a round hole, the square and round holes of the two members being aligned in the assembled arm. The square end of the rod 5 is received in the aligned square holes and both channel section members 12, 1 3 are welded to the rod 5. Similarly, the stub axle 3 is received in both round holes and is welded to both channel section members. Additionally, the channel section members 12, 1 3 can be welded together over their entire length at the free edges of the channel section member 12 and/or at the free edges of the channel section member 13.The resultant arm is of extremely strong construction and has the advantage that the square and round section holes have been formed by a simple punching technique during manufacture of the channel section members. In contrast, if a length of box section tube is used for the arm 4 the formation of square and round section aligned holes at opposite ends of the box section is difficult.

A plate 14 is welded to the end of the rod 5 remote from the arm 4 in order to ensure positive retention of the rod 5 even in the event of total disintegration of the packing rubbers.

It will be appreciated that the above described suspension unit can be simply dis-assembled to inspect and/or replace the packing rubbers simply by releasing the various clamping members securing the plate 6 to the channel member 7.

Further, this work can be carried out by the owner of a trailer fitted with the suspension unit or by any workshop without the need for specialist presses or the like to remove/replace the packing rubbers. Further, the suspension characteristics of the unit can be readily altered by replacing the packing rubbers with a different grade of rubber or by altering the length of packing rubber fitted within the unit. This work can be easily carried out to trim the suspension characteristics to the particular use to which the suspension unit is to be put.

Although the suspension unit has been described for use on a two-wheeled motor car towed trailer it will be appreciated that by suitably modifying the characteristics of the suspension unit it can be applied to a wide range of uses where it is desired to mount a ground engaging wheel on a body structure.

Claims

1. A suspension unit comprising an elongate hollow non-circular housing assembly which, in use, is secured to a body to be supported by the suspension unit; an elongate non-circular rod located in the housing assembly; a plurality of packing rubbers located between the housing assembly and the rod for resiliently yieldably resisting relative rotation of the rod and the housing; an arm extending radially outwardly from one end of the rod; and an axle extending parallel to the longitudinal axis of the rod secured to the arm at a point spaced from the rod, wherein the housing assembly includes a removable side member secured in position by clamping members, the clamping members being releasable to permit removal of the side member, the packing rubbers and the rod from the remainder of the housing assembly, and being tightenable during re-assembly of the unit to compressably preload the packing rubbers.

2. A suspension unit according to claim 1 wherein the rod is square in transverse cross section and is located in a cavity in the housing assembly which cavity is also square in transverse cross section, the rod being angularly displaced from the cavity to define between the rod and the walls of the cavity four generally triangular spaces within which the packing rubbers are located.

3. A suspension unit according to claim 2 wherein the rod is angularly displaced by 450 from the cavity when the suspension unit is not loaded, the diagonal dimension of the rod being slightly less than the distance between each pair of parallel sides of the cavity to define a small working clearance between the rod and the walls of the cavity.

4. A suspension unit according to any preceding claim wherein, in the unstressed state, the packing rubbers are circular in transverse cross section.

5. A suspension unit according to any preceding claim wherein the removable side member of the housing assembly is a flat plate and the remainder of the housing assembly comprises a top-hat cross section channel member, the plate being secured to the edge flanges of the channel member by the clamping members.

6. A suspension unit according to any preceding claim wherein the arm comprises two channel section members nested with each other to form a box-section member.

7. A suspension unit according to claim 6 wherein each channel section member of the arm has a square hole in which a square portion of the rod is located, and a round hole in which a round portion of the axle is located.

8. A suspension unit according to claim 6 or claim 7 wherein the rod and the axle are each welded to each channel section member of the arm.

9. A suspension unit according to any preceding claim wherein at least one of the packing rubbers extends along less than the full length of that portion of the rod which is located within the housing assembly.

10. A suspension unit substantially as hereinbefore described with reference to and as shown in the accompanying drawings.