d. Out-of-round (Rule 73--AAR symbol 73).
Although not dangerous, the out-of-round defect is
undesirable because of the damage it can cause to equipment, track, and lading when the car it is under is
traveling at high speeds. When the flattened area, regardless of the cause, is in excess of 3/64 inch within an arc
of 12 inches or less, measured in the center of the tread, the wheel is condemnable. Figure 2.3 shows the
application of the out-of-round gage for a wheel with a 33-inch diameter. Wheels with larger diameters must be
gaged with out-of-round gages made especially for wheels of their diameter; however, the size of the wheel for
which the gage is made is stamped on the gage.
e. Vertical Range (Rule 74--AAR symbol 74-V). The inserted sketch shows a wheel-defect gage applied to
the flange of a new
wheel; note that the spot marked "limit point" does not touch the flange. As the wheel
the rail, friction tends to wear down or flatten the inside vertical surface of the
flange, creating the defect called vertical flange or sharp flange. The sketch at
the top of figure
2.7 shows the wheel-defect gage applied to a flange worn
vertically; note here that the gage's limit point now touches the flange.
There are two limit points, a 1" limit and a 7/8" limit as seen in used
for two different car capacities: less than
pounds and 80,000 pounds or more. The
danger of the vertical flange defect is that the flange may split a
switch (take the wrong side of the switch point) and derail the
equipment or break the switch point.
On cars of less than 80,000-pound capacity, a wheel is condemned when
the flat vertical surface of the flange extends 1 inch or more above the tread and thus
touches the gage at the 1-inch limit point.
(2) On cars of 80,000-pound capacity or more, a wheel is condemned when the vertically worn surface
of the flange extends 7/8 inch above the tread and touches the gage at the 7/8-inch limit point.