Eccentric adjustment for vehicle axle suspensions

The background disclosure is of a somewhat typical tandem-axle vehicle suspension, especially for motor trucks, made up of a pair of spring-supported, fore-and-aft walking beams and a pair of transverse rear axles. The improvement resides in structure interconnecting the axle housing and walking beams to provide for fore-and-aft adjustment of the axle housing relative to each other and to the walking beams so as to assure or at least approach parallelism of the axle housing with respect to each other and perpendicularity thereof to the vehicle fore-and-aft centerline. Each end of each walking beam is connected to its associated axle housing portion by a pair of relatively angularly cooperative members of circular configuration but having eccentric axes so that when one member is turned relative to the other, the fore-and-aft relationship of the adjusted axle housing changes. The improved interconnecting structure ties in closely with existing parts, at least in some known designs of typical suspensions, mainly using rubber bushings in the interconnections so that each end of an axle housing may be adjusted relative to the other without imposing undue stresses.

BACKGROUND OF THE INVENTION 
A typical tandem-axle motor vehicle rear suspension will include right and 
left walking beams pivotally carried intermediate their front and rear 
ends on the vehicle frame, usually by means of leaf springs or the like. A 
pair of transverse axle housings is arranged to span the walking beams 
adjacent to their front and rear ends. Conventional connecting structure 
between the axle housings and walking beams includes, at each end of an 
axle housing, a pair of ears welded to the housing and spaced apart 
laterally so as to straddle the associated end of the walking beam. These 
ears are provided with circular openings coaxial with a transverse bore 
through the end of the walking beam and appropriate bushings and tie means 
are utilized to pivotally interconnect the housings and beams for relative 
movement about several transverse axes. 
The basic problem encountered in systems of this type arises from the fact 
that the axle housing ears are seldom accurately positioned relative to 
the housing before welding and, if they are, the heat generated by the 
welding operation quite often distorts the relationship, with the end 
result that the suspension, when ultimately assembled, includes axle 
housings out of parallelism and one or the other or both housings are 
non-perpendicular to the fore-and-aft centerline of the vehicle. 
Substantial misalinement, distortion and other forms of inaccuracies lead 
to excessive wear on the vehicle tires, bearings and power train. Certain 
of these inaccuracies lend themselves to correction by cutting the 
offending ears off the housing and re-welding them. This type of 
correction is costly, time-consuming and more often than not fails to 
completely solve the problem. 
According to the present invention, the suspension is improved by replacing 
each connection between walking beam and axle housing with a connection 
having provision for adjustment of the axle housings relative to each 
other and to the walking beam by simple adjusting means operative without 
re-welding or otherwise interchanging parts. The preferred form of the 
invention utilizes a pair of eccentrically related members which, when 
moved angularly relative to each other, create fore-and-after movement of 
that end of the axle housing previously determined to be out of line. 
Provision is made for effecting the adjustment by a simple tool, such as a 
wrench or the like. Tie means is provided for securing the adjustment 
after it is made. Further means is provided for easily releasing the parts 
for readjustment. 
Further details of the invention and features and advantages thereof will 
become apparent to those skilled in the art as a preferred embodiment of 
the invention is set forth below.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
Reference will be had first to FIGS. 1 and 2 in terms of background for the 
invention. Those versed in the art will recognize the rear part of a motor 
vehicle or like main frame 10 having at each side thereof typical leaf 
spring means 12, each of which, via a transverse pivot 14, carries an 
equalizing or walking beam 16. The walking beam extends fore-and-aft 
symmetrically as respects the pivot 14 and has front and rear ends 
connected to and supporting front and rear transverse axle housings 18. 
That one of the housings may house drive axle means is not material here 
and, thus, those details are omitted. As best seen in FIGS. 2, 3, 6 and 7, 
each axle housing carries rigidly therewith at each outer end portion a 
pair of laterally spaced apart ears 20 which straddle the proximate end 
portion of the associated walking beam. Each ear has therein a circular 
opening 22, and these are of like diameter and coaxial on a transverse 
axis theoretically parallel to the axis of its axle housing. In the form 
of the invention chosen for purposes of the present disclosure, each end 
of the walking beam is provided with an elongated through bore or opening 
24 which is fitted interiorly with a resilient bushing 26 of rubber or 
like material. Such bushings in general are known in conventional 
suspensions, especially that known as the Hendrickson Tandem. Similar 
arrangements involving axle-to-walking beam or equivalent fixed-length 
supports by means such as bushings of rubber or the like, are found in 
other tandem-axle suspensions; e.g. the Neway design. In any event, the 
bushing itself, of course, provides a through bore 28. 
As noted earlier herein, it is also conventional to provide the apertured 
axle housing ears. Thus, the improvement is able to employ conventional 
background structure, which simplifies its manufacture and use and lowers 
its cost. The novel interconnecting structure includes means providing a 
steel cross element 30 which includes, preferably integral with each 
other, a cylindrical midportion 32 and opposite end cylindrical portions 
34 of reduced diameter. The midportion fits the rubber bushing 28 and the 
end portions project respectively beyond opposite sides or faces of the 
walking beam and respectively into the openings in the axle housing ears 
20. The cylindrical portions are of like diameter which is substantially 
smaller than that of the ear openings. As a further part of the preferably 
one-piece element 32, integral coaxial threaded extensions 36 project 
oppositely outwardly from the cylindrical portions. 
The interconnecting structure further includes a pair of adjustment members 
38, one at each end of the cross element 30. Each such member is of steel 
or like material and has at its inner side a cylindrical pocket or bore 40 
rotatably receivable by the adjacent cylindrical portion 34 of the element 
30. Each adjustment member further has at its inner side a cylindrical 
periphery or surface 42 which is rotatably receivable by the circular 
opening in the adjacent housing ear 20. But the axes of the bore 40 and 
surface 42 are eccentric to each other so that, when the adjustment member 
is manually turned about the cylindrical element portion 34 as a center, 
the eccentricity of the axes causes the cylindrical surface to shift the 
axle housing fore and aft relative to the walking bean within the limits 
established by the offset or eccentricity of the two axes just referred 
to. This will be best understood by viewing FIGS. 6 and 7, where the 
letter A designates the center of the member 30 and the letter B 
designates the center of the adjustment member 38. In FIG. 6, B is to the 
right or ahead of A meaning that the axle housing has been shifted 
forwardly to its maximum forward position. In FIG. 7, the centers are 
reversed to show the maximum rearward shift of the axle housing, both 
adjustments of course being relative to the associated walking position, 
the fore-and-aft position which is of course fixed by the pivot of the 
walking beam at 14. It will be understood that when the adjustment is made 
at one end of the axle housing, the housing in effect "pivots" at the 
rubber bushing at its opposite end. It should also be understood that both 
adjustment members should be turned simultaneously and for this purpose, 
each adjustment member has an integral circular flange 44 provided 
exteriorly with a lug 46 or equivalent tool-receiving part for receiving a 
tool such as a wrench. 
When assembled, the flanges overlie the outer axle housing ears and the 
inner ends of the adjustment members abut the shoulders on the element 30 
at the junctions of the portions 34-32-34 to maintain lateral positioning 
of the parts. Each adjustment member has a central opening 48 through 
which the proximate threaded extension 37 of the element 30 projects. The 
opening 48 terminates exteriorly as a conical cavity 50 and, at each end, 
a conical or "lug" nut 52 is threaded onto the proximate extension, 
seating in the cavity and completing the tie means that ties the structure 
together in the assembled condition shown in FIG. 3. Once the selected 
adjusted position is achieved, it is secured by locking means, here 
comprising a pair of set screws 54 threadedly carried by the adjustment 
member via tapped bores 56 and extending therethrough to engage the 
associated housing ear. Each set screw may be of the type having a 
hardened point so as to bite into the ear in order to prevent accidental 
angular movement of the adjustment member relative to the ear. When it is 
desired to disassemble the structure for replacement, readjustment, etc., 
the tie nuts are removed or loosened and the set screws further tightened, 
which serves to jack the adjustment member out of its dual fit with the 
housing ear and cylindrical portion 34. 
It will be understood that the foregoing has proceeded on the basis of a 
preferred embodiment of the invention and it follows that many 
modifications may be made in that structure without departing from the 
spirit and scope of the invention.