﻿GET_GEVOMechL2_06_01_01_12 - ANIMATION Screen
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Wear and wheel change-outs may cause wheel diameters to become unequal, resulting in greater differences in weight distribution between the axles. 

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Using shims allows greater differences in wheel diameters between wheel sets while keeping axle loading more uniform.

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Shims are inserted between the coil springs and the spring pads.

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<b>Note:</b> FRA Rule 229.73b limits differences in diameter between any two wheel sets in a truck to 3/4 inch (19.1 mm) if shimming is not used.

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If shims are used at the axle bearing housing springs, the rule permits a difference up to 1-1/4 inches (31.8 mm). 

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The same 1-1/4 inch (31.8 mm) difference is allowed between any two wheel sets on different trucks.

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<b>Note:</b> Although 1-1/4 inch (31.8 mm) difference in wheel diameter is acceptable as an FRA limit, wheel diameter variations greater than 1 inch (25 mm) can reduce locomotive performance.

