December 2, 1991

CIRCULAR LETTER
(C-7751)

SUBJECT: Cone Face Wear Groove Limit

TO: Members and Private Car Owners

GC-WABL
TB-10B
(C-7751)

In order to define limits for the journal roller bearing cone wear groove which results from fretting action between the cone face and the seal wear ring due to axle flexure in service, the Wheels, Axles, Bearings and Lubrication Subcommittee advanced revisions to Section H-Part II, Rule 3.21 and established a new Figure 3.6.a as shown on the attached pages.

These revisions are effective March 1, 1992 and 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

Section H-Part II

Present

Rule 3.21
Inner Ring: Inner rings must be inspected for the same defects as outer rings (See Rule 3.20). The inner ring must be inspected as shown in Figures 3.7 and 3.8 or by any suitable method which will indicate condition of inner race. The inside diameters must be checked with dial bore gage (Figure 3.6) or other gages.

Proposed

Rule 3.21
Inner Ring: Inner rings must be inspected for the same defects as outer rings (See Rule 3.20). The inner ring must be inspected as shown in Figures 3.7 and 3.8 or by any suitable method which will indicate condition of inner race. The inside diameters must be checked with dial bore gage (Figure 3.6) or other gages. Cone
face wear depth shall not exceed 0.010 - inch as illustrated in Figure 3.6.a.

Present

Figure 3.6.a Vacant

Proposed