March 21, 1988

SUBJECT: Elimination of Requirement for Application of Roller Bearing Cap Screw Seal Rings
TO: The Member and Private Car Owners Roller Bearing Manufacturers and Reconditioners

GC-1463
TWBL - 23A
(c-7269)

Gentlemen:

In a continuing effort to improve roller bearing performance and to decrease the occurrences of overheated bearings, the AAR Wheels, Axles, Bearings and Lubrication Committee has decided to remove the requirement for and prohibit the further application of cap screw seal rings in the assembly of new, reconditioned and secondhand roller bearings.

Tests have conclusively verified that, significant undesirable reduction in clamp force levels on the bearing is directly attributable to adverse seal ring compression properties during tightening of the cap screws. Most importantly, this condition can lead to loosening of components which can produce overheating in service. Further, the Roller Bearing Manufacturers' Engineers' Committee (RBMEC) attests that the use of cap screw seal rings dows not in fact provide meaningful benefits in resistance to water intrusion as originally anticipated.

Accordingly, in consideration of testing results and other evidence that roller bearing performance will be enhanced, effective with the receipt of this notification, cap screw seal rings need not be applied. Additionally, after May 1, 1988, application is prohibited.

In accordance with the provisions of AAR Standard S-050, the comments of all affected or interested parties in regard to the indicated prohibition are herewith solicited. Responses should be submitted to the Association of American Railroads to the attention of the Secretary, Mechanical Division, within 30 days of the date of this circular.

Sincerely,

Leavitt A. Peterson