AUSTRALIA PATENTS ACT 1990 COMPLETE SPECIFICATION INNOVATION PATENT A VEHICLE SUPPORT ARM ASSEMBLY The following statement is a full description of this invention including the best method of performing it known to me: A VEHICLE SUPPORT ARM ASSEMBLY TECHNICAL FIELD 5 The present invention relates to a support arm assembly for supporting a vehicle axle assembly relative to a vehicle chassis. The present invention has particular, although not exclusive application to four-wheel drive (4WD) vehicles. 10 BACKGROUND The reference to any prior art in this specification is not, and should not be taken as an acknowledgement or any form of suggestion that the prior art forms part of the common general knowledge. 15 Figure 1 shows a known support arm 2 (also called a "radius arm") for supporting a vehicle differential assembly 4 (Figure 2) incorporating an axle assembly. In practice, a like pair of support arms 2 supports the differential assembly 4 on either side of the vehicle differential (not shown) which, in turn, 20 drives a pair of wheels via an axle. The doglegged support arm 2 is elongate and includes a threaded shaft 6 at one end for fastening the arm to the vehicle chassis (not shown) using a complementary fastening nut. The support arm 2 defines two apertures 8a,b 25 at the other end which facilitate mounting to the differential assembly 4 as explained below. Referring to Figure 2, a support arm assembly 10 including the support arm 2 is used to support the vehicle differential assembly 4 relative to the vehicle 30 chassis. The support arm assembly 10 further includes a pair of couplers 12a,b force fitted within respective apertures 8a,b. The couplers 12a,b resiliently couple the support arm 2 to a pair of opposite mounting lug sets 14a,b of the differential assembly 4.
Retuning to Figure 1, each coupler 12 includes a resilient rubber bushing 16 for being received in a corresponding aperture 8 defined in the arm 2. Each coupler 12 further includes a rigid tubular core 18 fitted within the bushing 16 and for receiving the shaft of a respective fastener. The fastener is in the form 5 of a threaded nut and bolt assembly 20 (see Figure 2). Returning to Figure 2, each mounting lug set 14 includes a pair of parallel plate-like mounting lugs 22. In use, the support arm assembly 10 is located between the mounting lug sets 14a,b so that coupler 12a is between one pair 10 of mounting lugs 22a,22b and coupler 12b is between the other pair of mounting lugs 22c,22d. The tubular cores 18 of the couplers 12 are aligned with mounting holes defined in the lugs 22. The shafts of the nut and bolt assemblies 20 pass through the mounting holes and the tubular cores 18. 15 The foregoing arrangement of Figure 2 is suitable for use in a four wheel drive (4WD) vehicle. As the 4WD vehicle traverses uneven terrain, the differential assembly 4 can move relative to the support arm 2 (and therefore the vehicle chassis) owing to the resilience of the couplers 12a,b. 20 SUMMARY OF THE INVENTION According to one aspect of the present invention, there is provided a support arm assembly for supporting a vehicle axle assembly relative to a vehicle chassis, the support arm assembly including: 25 a support arm for extending from the chassis and for supporting resilient coupling means, the support arm defining two apertures for receiving respective resilient couplers of the resilient coupling means, the apertures being located on the same side of a vertical plane extending through and along an axle of the vehicle axle assembly; and 30 mounting bracket means for mounting to the axle assembly and the resilient coupling means. Optionally, the support arm is elongate and includes fastening means including a threaded shaft extending along the arm at one end for fastening 3 the arm to the chassis. Optionally, the two apertures are located at the other end. Optionally, the mounting bracket means includes a pair of mounting brackets 5 for cradling the axle assembly from below. Optionally, each mounting bracket is shaped to form a recess for receiving the axle assembly, and has a pair of apertures defined at either end for receiving fasteners that pass through opposing lugs of the axle assembly. 10 BRIEF DESCRIPTION OF THE DRAWINGS Preferred features, embodiments and variations of the invention may be discerned from the following Detailed Description which provides sufficient 15 information for those skilled in the art to perform the invention. The Detailed Description is not to be regarded as limiting the scope of the preceding Summary of the Invention in any way. The Detailed Description will make reference to a number of drawings as follows: 20 Figure 1 is a perspective view showing a vehicle support arm according to the prior art; Figure 2 is an upper perspective view showing the support arm of Figure 1 supporting a vehicle differential assembly according to the prior art; 25 Figure 3 is a perspective view showing an unassembled support arm assembly in accordance with an embodiment of the present invention; Figure 4 is a perspective view of the support arm assembly of Figure 3; and 30 Figure 5 is an upper perspective view showing the support arm assembly of Figures 3 and 4 supporting a vehicle differential assembly.
4 DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS The use of any reference numerals below which have also previously been used, refer to like features previously described. 5 According to an embodiment of the present invention, there is provided an unassembled support arm assembly 30 as shown in Figure 3. The support arm assembly 30 is suitable for supporting a vehicle differential assembly 4 (see Figure 5) including an axle 50 relative to a vehicle chassis (not shown). 10 The support arm assembly 30 includes a support arm 32 for rigidly mounting to extend from the chassis. The support arm assembly 30 further includes a pair of mounting brackets 34a,34b for rigidly mounting to the differential assembly 4. A pair of couplers 12a,12b are also provided for resiliently coupling the support arm 32 relative to the mounting brackets 34a,34b. A 15 detailed description of the support arm assembly 30 is provided below. Turing firstly to Figure 3, the elongate support arm 30 is bowed and includes a threaded shaft 36 at one end for fastening the arm 30 to the chassis using a complementary fastening nut (not shown). The support arm 30 defines two 20 apertures 38a,b at the other end which are located in close proximity to each other so that, in use, they are both located on the same side of the differential assembly 4. The endmost aperture 38b is of smaller size than the innermost aperture 38a. 25 Each coupler 12 includes a resilient outer rubber bushing for being received in a respective aperture 38 defined in the arm 32. Each coupler 12 further includes a rigid metal tube fitted within the bushing and for receiving the shaft of a respective bolt. In use, the couplers 12a,b are force fitted within respective apertures 38a,b. 30 Each mounting bracket 34 is generally "L-shaped" to form a cradle for passing under and cradling the differential assembly 4. Each mounting bracket 34 defines a triplet of holes 40. For each bracket 34, one pair of the holes 40 can align with corresponding holes of mounting lugs 22 of the differential assembly 5 4 (Figure 5) and another pair of the holes 40 can align with corresponding metal tube cores of the couplers 12. The support arm assembly 30 further includes a rigid tubular spacer 42 for 5 being fastened between the mounting brackets 34a,b in the location shown in Figure 4. Returning to Figure 3, a triplet of threaded bolts 44 are provided for passing through holes 40 of the mounting brackets 34a,34b. A triplet of complementary threaded fastening nuts 46 are provided for engaging with the bolts 44 to hold the support arm assembly 30 together as shown in Figure 5. 10 Turning to Figure 5, the differential assembly 4 includes a pair of opposite mounting lug sets 14a,b. Lug set 14a includes a pair of parallel mounting lugs 22a,22b whereas lug set 14b includes a pair of parallel mounting lugs 22c,22d. Each mounting lug set 14 defines a pair of aligned holes (i.e. one in 15 each lug 22) through which the shaft of a bolt 44 can pass. In use, the support arm assembly 30 shown in Figure 4 is located between the parallel mounting lugs 22 of the mounting lug sets 14a,b as shown in Figure 5. The triplet of bolts 44 (and nuts 46) is then used to fasten the support arm 20 assembly 30 to the differential assembly 4. One of the bolts 44 passes through the lug 22a, mounting bracket 34a, coupler 12a, mounting bracket 34b and then lug 22b. Another one of the bolts 44 passes through mounting bracket 34a, coupler 12b and then mounting bracket 34b. The final bolt 44 passes through the lug 22c, mounting bracket 34a, spacer 42, mounting 25 bracket 34b and then lug 22d. Mounting bracket 34a is rigidly mounted to lugs 22a and 22c whereas mounting bracket 34b is rigidly mounted to lugs 22b and 22d. The fastening joints about the couplers 12a,b are resilient whereby the couplers 12a,b 30 resiliently couple the support arm 32 (fixed to the chassis) relative to the mounting brackets 34 (fixed to the differential assembly 4). The degree of movement of the differential assembly 4 relative to the support arm 32 is greater than that of the differential assembly 4 relative to the support arm 2 previously described in the background.
6 In practice, the applicant has found that having a pair of support arm assemblies support the differential assembly 4 on either side of the vehicle differential (not shown) yields desirable results, when the support arm 5 assembly 10 is provided on the driver side of the vehicle and the support arm assembly 30 is provided on the passenger side of the vehicle. In this manner, the differential assembly 4 is prone to axial twist in use. Referring to Figure 5, the differential assembly 4 further includes a tubular 10 axle 50 from which the opposite mounting lug sets 14a,b outwardly extend. The axle 50 is cradled by the brackets 34a,b and extends from the differential. A suspension seat 52 is located on top of the differential assembly 4 and, in use, supports the wheel suspension system. A drive shaft (not shown) extends from the differential within the tubular axle 50 and terminates in an 15 external wheel mounting plate 54 to which one of the vehicle wheels can be mounted. In practice, the support arm assembly 30 can be retrofitted to a vehicle in place of the support arm assembly 10. Firstly, the support arm assembly 10 is 20 removed from the vehicle. A retro-fit method for mounting the support arm assembly 30 to support the vehicle differential assembly 4 relative to the vehicle chassis is now described. The method includes the steps of: (1) mounting the support arm 32 to extend 25 from the chassis; (2) mounting the brackets 34a,b to the mounting lug sets 14a,b of the differential assembly 4; and (3) resiliently coupling the support arm 32 relative to the mounting brackets 34a,b using the couplers 12a,12b. The foregoing steps can be performed in any order. 30 A person skilled in the art will appreciate that many embodiments and variations can be made without departing from the ambit of the present invention.
7 In the preferred embodiment, the brackets 34a,b were mounted within the confines of the lugs 22. In an alternative embodiment, the brackets 34a,b can be mounted to the outside of the lugs 22 so that the lugs 22 are located between the brackets 34a,b. 5 In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. It is to be understood that the invention is not limited to specific features shown or described since the means herein described comprises preferred forms of 10 putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted by those skilled in the art.