are stamped on the back face of the wheel rim approximately one-fourth inch from the inner edge of the rim.
(2) On AAR-MW wheels, the month and year of manufacture, the brand and serial number of the
manufacturer, the heat number, and the class (A, B, or C) along with the method of heat treatment are stamped
on the back face of the rim approximately one-fourth inch from the edge of the rim. The method of heat
treatment mentioned here and in the preceding paragraph and the class of the wheel are marked together. The
following list shows these marks and what they mean.
AR - Class A, rim treated.
AE - Class A, entire wheel treated.
BR - Class B, rim treated.
BE - Class B, entire wheel treated.
CR - Class C, rim treated.
CE - Class C, entire wheel treated.
Note: Class U, untreated wheels, are not marked for class.
2.7. LIMITS OF WHEEL WEAR AND WHEEL DEFECTS
Now that you are familiar with the types of wheels, we are ready to examine how much each type of wheel
may be worn before it is removed from service or restored to original contour. The next paragraphs describe,
first, the wheel gages used in measuring wear on different parts of a wheel; second, the most common defects
found in cast-steel wheels; and third, those in wrought-steel wheels.
The tools you use to find out the amount of wheel wear and the extent of defects are gages. Only four
gages are described here; they are the most frequently used. There are others which you might have to use if
you were inspecting wheels, especially new ones.
Used for a number of inspections, as you can tell from its long name, is the gage called the wheel defect,
worn coupler limit, worn journal collar, and journal fillet.
It is shown in the top sketch in figure 2.3.
Throughout the rest of the discussion on wheels, this gage is referred to only as the wheel-defect gage; in later
parts of your text, its other uses are explained. The wheel-defect gage is used mainly on cast-steel wheels. Two
other gages, the tread-worn-hollow and the out-of-round, measure the two defects of the