Axle

Part Reference
The axle is the portion of a wheelset upon which the wheels and bearings[kw] are mounted.

Condemning Criteria

Condemning criteria are outlined in [kw]AAR Field Manual Rule 43 ("Axles")

Axle Sizes

Axle dimensions are standardized by the AAR in MSRP Section G, Specification M-101. These include:
  • Class D (5-1/2 x 10)*
  • Class E (6 x 11)
  • Class F (6-1/2 x 12)
  • Class K (6-1/2 x 9)
  • Class G (7 x 12)
  • Class L (6 x 8)*
  • Class M (7 x 9)
* - No longer used in North American Interchange Service

Production of New Axles

New axles can be forged or rolled from either cast ingots or from strand-cast blooms. Once the rough shape is attained through forging or rolling, the axle is straightened, heat-treated, and machined. Before being released for shipment to wheel shops, all axles undergo a rigorous evaluation process which includes both radial and axial Ultrasonic Testing. Each axle is stamped with a unique serial number, manufacturer's name, month and year made, grade of axle (type of heat treat), and heat identification number.

AAR Technical Committee

The AAR Technical Committee overseeing axles is the WABL (Wheels, Axles, Bearing, and Lubrication) committee