June 20, 1988

SUBJECT: Cap Screw Gage
TO: The Member and Private Car Owners Roller Bearing Manufacturers and Reconditioners

GC-1463
TWBL - 23A
(c-7286)

Gentlemen:

In a continuing effort to improve roller bearing performance and assure a positive clamp force on the roller bearing to prevent the loosening of bearing components which can produce overheating in service, the AAR Wheels, Axles, Bearings and Lubrication Committee is revising Section H-II, Rule 3.27, as shown below, to include the use of a cap screw gage, shown in Figure 3.18, to check for cap screw body stretching or bent condition.

Present

Rule 3.27
Cap Screws: Check threads for damage and wear. Check cap screw body for stretching or elongation (this usually will show in the first 1" length of cap screw under head, as an elongation of pitch, which can be compared to that of a new cap screw). Reject for burrs extending beyond the washer face on the underside of the cap screw head as these will damage the locking plate. If any defect is found in cap screw it must be rejected.

Revised

Rule 3.27
Cap Screws: Check threads for damage and wear. Check cap screw body for stretching or bent condition using gage shown in Figure 3.18 or other AAR approved method. Reject for burrs extending beyond the washer face on the underside of the cap screw head as these will damage the locking plate. If any defect is found in cap screw it must be rejected.

This revision will be effective August 1, 1988 and will be placed in the next revision of Section H of the Manual of Standards and Recommended Practices.

Sincerely,

Leavitt A. Peterson