§ 229.73 Wheel sets.
Current through Sep 25, 2026 · Read all of Part 229
(a) The variation in the circumference of wheels on the same axle may not exceed 1/4 inch (two tape sizes) when applied or turned.
(b) The maximum variation in the diameter between any two wheel sets (the average diameter of the two wheels on an axle) shall not exceed the following:
(1) Within the same three-powered-axle truck, 3/4 inch, except that when shims are used at the journal box springs to compensate for wheel diameter variation, the maximum variation may not exceed 1 1/4 inches.
(2) On different trucks on a locomotive that has three-powered-axle trucks, 1 1/4 inches.
(3) For powered axles on locomotives equipped with alternating current traction motors that utilize individual truck or single axle control technology, 1 1/2 inches, with or without shims. For non-powered axles in the middle of two powered axles, this paragraph (b) does not apply.
(c) On standard gauge locomotives, the distance between the inside gauge of the flanges on non-wide flange wheels may not be less than 53 inches or more than 53 1/2 inches. The distance between the inside gauge of the flanges on wide flange wheels may not be less than 53 inches or more than 53 1/4 inches.
(d) The distance back to back of flanges of wheels mounted on the same axle shall not vary more than 1/4 inch.
[45 FR 21109, Mar. 31, 1980, as amended at 91 FR 55779, Aug. 31, 2026]