AAR Circular Letter
C-8751

August 15, 1997

CIRCULAR LETTER

(c-8751)

Subject: Section G, Part II, End Cap Application Requirements

TO MEMBERS AND PRIVATE CAR OWNERS

File Number: TB-1.1

The Wheels, Axles, Bearings and Lubrication Committee has approved the following revision to Section G, Part II, Rule 1K11 as follows:

Rule 1K11

End cap application is one of the most critical wheel set processes. Any improvements in clamping forces made here is likely to extend the application life of the bearing. Improper application is certain to reduce application life and may cause catastrophic failure. The following optimizes bearing performance:

New locking plates, marked in accordance with Fig. 4.57, must be used in all bearing applications
When possible, end caps should be of the same manufacturer as the roller bearing applied. When this is not the case, end caps must meet the requirements of Rule 1K19.
End caps must not have a lubricant fitting.
New cars must be equipped with new bearings, new end caps and new cap screws. These bearings must be torqued to the higher torque values listed in the "NEW END CAP / CAPSCREWS" column of Fig. 4.43.
Mounting shops may choose to apply any or all bearings using the torque values listed in the "NEW END CAP / CAPSCREWS" column of Fig. 4.43 provided new end caps and capscrews are used.
In all other applications, new or secondhand end caps and new or secondhand cap screws may be intermixed with new or reconditioned bearing. Because some used end caps and cap screws cannot tolerate the higher torques, these bearings must be torqued to the lower torque value listed in the "SECONDHAND END CAP / CAPSCREWS" column of Fig. 4.43.

Note: See Fig. 4.42 for Amtrak Passenger Car End Cap Application

Association of American Railroads

Wheel and Axle Manual

FREIGHT CARS

Class (Journal Size)	Cap Screw Size	Secondhand End Cap / Capscrews – Torque	New End Cap / Capscrews – Torque
D (5 ½ X 10)	⁷/₈" X 9	145	200
E ( 6 X 11)	1" X 8	265	295
F (6 ½ X 12)	1 ¹/₈" X 7	385	420
G (7 X 12)	1 ¼" X 7	450	530

AMTRAK CARS

G (6 ½" Diameter)	⁷/₈" X 9 High Strength	315	315
	⁷/₈" X 9	145	145
EE (6" Diameter)	⁷/₈" X 9	145	145
EE (5 ½" Diameter)	¾" X 10	115	115

Cap Screw Torque in Foot Pounds To Bo Posted in Work Area In Roller Bearing Mounting Shops

Torque wrenches must be accurate within +/- five percent.

The Committee believes that this rule change will improve clamp force and extend the application life of the roller bearing.

In accordance with the provisions of AAR Stands S-050, your comments on this proposal are solicited. All comments received will be considered by the Committee prior to finalizing the proposed specification changes. Replies should be addressed to the Director – Equipment Performance, and be received within thirty days of the date of this Circular.

Sincerely,

David C. Meeks

Director – Equipment Performance