May 28, 1976

Subject:Summary of Application and Maintenance Practices for the No-Field Lubrication (NFL) Bearing

TO THE MEMBERS AND PRIVATE CAR OWNERS

File No. C-6033

Gentlemen:

The NFL Bearing has been approved by the AAR for interchange service. This bearing is not to be lubricated in the field. Bearing manufacturers have been authorized to begin delivery of new and reconditioned NFL bearings as early as June 1, 1976, with December 1, 1976 as the mandatory date.

The purpose of this letter is to alert member companies to some of the changes in bearing application and maintenance practices which will be described in detail in the Field Manual and in the Roller Bearing Manual, which should be distributed in mid-June 1976. Pertinent information is also available in the Annual Report of the Wheels, Axles, Bearings and Lubrication Committee (Circular No. D.V. 1869, dated May 23, 1976).

Companies may apply and/or repair NFL bearings as soon as they have the necessary instructions and materials.

The distinguishing characteristics of the NFL bearing are:

1. End cap without lubrication fitting - see the Roller Bearing Manual, Appendix B, or Circular No. D.V. 1869, page 60.

2. Elastomeric cap screw seal rings on cap screws between end cap and end of axle - see Roller Bearing Manual, Appendix B, or Circular No. D.V. 1869, page 60.

3. Only approved greases to AAR Specification M-942 may be used and the amounts are specified in Roller Bearing Manual, Figure 5.23 (Currently approved greases are Exxon ARAPEN RB-320 and Shell ALVANIA-D)

Application
The NFL bearing requires caulking at the backing ring - axle dust guard seat juncture after mounting, unless a fitted backing ring is used. The currently approved caulking compounds are Alumilastic C (PARR Inc.), Weatherban 202 (3M Company), White Butyl Caulk (Rutland Prod.) and Mortell #44 Rubberized Caulk-White (extruded form). Cap screw seal rings must be in place prior to applying end cap. These seal rings are not reusable.

Car Stenciling
Stenciling for the NFL bearing is the same as for Cars Equipped with Bearings Not Requiring Lubrication, Field Manual, Rule 26, A.1.f.

Wheel Shop
NFL bearings mounted on one-wear wheels are not to be lubricated. Bearings mounted on two-wear and multiple-wear wheels will be lubricated only if the service metal after turning is 7/16 or less. A special lubrication fixture is required (see Roller Bearing Manual, Figure 3.2). Amount of AAR M-942 grease to add is 6 ounces for size 11 bearings or less and 10 ounces for all 12 bearings.

Bearing Repair Shops
Bearings converted to the NFL configuration must meet the current Roller Bearing Manual inspection criteria and be lubricated with AAR M-942 grease in amounts specified in the Fifth Edition (1976) of the Roller Bearing Manual, Figure 5.23. Lubrication fittings must be removed and replaced with a non-removable plug of one of the types specified in Appendix B of the Roller Bearing Manual.

It is imperative that no attempt be made to repair NFL bearings or to convert bearings to the NFL configuration until the instructions contained in the Fifth Edition of the Roller Bearing Manual are available and the proper materials are on hand.

Sincerely,

R. C. Reber
Secretary