October 31, 1991

CIRCULAR LETTER
(C-7730)

SUBJECT:Implementation of Letter Ballot Proposal 5 -- Revision to Section H-Part II, Rule 1.15 Reparation of Raceway Spalls.

TO:Members and Private Car Owners

GC-1463
TWBL-25
(C-7730)

Circular Letter c-7640, dated April 10, 1991, enlisted the views of interested and involved parties on proposed rule changes to lower bearing failure rates as caused by spalls on raceway surfaces. The proposed changes sought to attain meaningful improvement in performance by tightening the allowable frequency of repaired spalls in a defined area and by requiring that certain previously unrepaired spalls on the inner raceway be repaired.

Thereafter, on July 19, 1991, this proposition intended as an initial step toward reduction of bearing faulure rates, was duly submitted to the vote of members via Proposal No. 5 in Mechanical Division Letter Ballot Circular No. D.V. 2190.

The resultant balloting was in favor of adoption; and after consideration of recommendations and/or reasons advocating modifications advanced in the responses, the General Committee unanimously adopted the proposal.

As a result, the Wheels, Axles, Bearings and Lubrication Subcommittee of the Car Engineering Committee has approved the following revisions:

Summary of Section H-Part II, Rule 1.15

Allow not more than two spalls 1/16" by 1/16" or less be repaired by grinding in a 2" circumferential section of a raceway.

The total number of repaired spalls may not exceed six in any raceway.

Small spalls on the bearing inner ring raceway less than 3/32" by 3/32" in size, must be repaired before being returned to service.

Repairable spalls specified by this rule must be marked in a location near the spall, but not on the raceway, by the approved shop performing the repair. The mark shall be made in such a fashion as not to nick or further damage the raceway.

These revisions are effective January 1, 1992 and detailed standards will be incorporated in a subsequent publication of revised pages to Section H-Part II of the Manual of Standards and Recommended Practices.

Sincerely,

Leavitt A. Peterson