COUPLING AS 9X7595 - Caterpillar

Service Interval for Front Axle Idler Hubs
Front idler bearing life on Challenger 65, Challenger 65B, and Challenger 75 Agricultural Tractors typically appears to be between 2000-2500 hours. The reference article dated January 20, 1992, recommends that machines with over 2000 hours have spindle bearings replaced. The service replacement parts may be the original bearing cups and cones, but it is recommended they be the new longer life "P900" bearings (see description in the Bearing section).
One difficulty in diagnosing bearing condition was the lack of maintenance requirements for the front hub assembly. The original Operation & Maintenance Manuals did not require an oil change interval for the front idler hubs. Rather, a visual oil check was all that was required. This made early diagnosis of imminent bearing failure difficult, as oil changes/Scheduled Oil Samples (S O S) did not occur.
As a result, a Service Magazine article dated January 20, 1992 also added a scheduled oil change for the front idler hubs at 500 hours or annually. This new interval applies to all Challenger 65, Challenger 65B, and Challenger 75 Agricultural Tractors. The oil should be checked visually or by S O S oil analysis for the presence of steel flecks or for excess iron which could indicate a bearing failure in progress. If replacement is indicated, refer to the Service Magazine article dated December 27, 1993, for procedures to check reusability of the spindle and hub assembly and for proper installation instructions.
Changes to Front Axle Components
The changes to the hub assembly, spindle, and bearings are summarized in the following chart.
A detailed description of each of the changes shown in the chart is described in the following paragraphs.
8R-0625 Spindle
The 8R-0625 Spindle was originally specified with a larger diametrical tolerance and a rougher surface finish in the inner and outer bearing cone contact areas. The surface finish specification allowed undesirable machine turning grooves which met specifications, but engaged bearing cones only on the top edge of the machining grooves. This minimal surface engagement with the spindle increased the likelihood of bearing cone spinning on the spindle. As a result, a new 106-1597 Spindle was used that had refined tolerances and surface finish specifications that disallowed turning grooves to be present.
8R-5037 Hub Assembly.
The 8R-5037 Hub Assembly was originally equipped without a drain plug. A magnetic drain plug was subsequently added in production and announced with the Service Magazine article dated January 20, 1992. At about the same time, Hub Assemblies were found to have inadequate cup retention and were to be inspected for possible loose press of the bearing cups at the next service check. See the Service Magazine article dated March 2, 1992. With the added drain plug, the hub assembly oil could be easily changed at the recommended 500 hour service interval. The magnetic plugs collect material that could indicate an imminent bearing failure before it occurs.
Subsequently, the 8R-5037 Hub Assembly was canceled and replaced by the 8R-6631 Hub, magnetic drain plug, new "P900" bearing cups (see bearing section), and