MIL-DTL-29229B(YD)
6. NOTES
(This section contains information of a general or explanatory nature that may be helpful, but is
not mandatory.)
6.1 Intended use. These crane track fittings are the standard design of the NAVFAC for two-rail,
double flange wheel, portal crane trackage and conform to NAVFAC criteria for portal crane
track alignment. They are intended for use in new construction and in rehabilitation of existing
trackage, where conditions will permit. While a similar commercial product may be available in
railway practice for single flange wheels, equivalent designs for double flange wheels are not
commercially available.
6.1.1 Rigid frogs. Class B, styles 1 and 2, rigid frogs are two alternative designs which differ in
the cross section of the flangeway for use by standard gage railroad wheels.
6.1.1.1 Style 1. The style 1 rigid frog provides a standard AREA flangeway (1.875 inches
(47.625 mm) deep) through the entire railway intersection. Railroad wheel loads are carried in
normal fashion, bearing only on the treads of the wheels. No ramps for railroad wheel flange
bearing across the area of railway intersection are provided. This results in a notch through the
crane wheel flangeways (0.875-inch (22.225 mm) deep) due to the difference in depth of railroad
and crane wheel flanges.
6.1.1.2 Style 2. The style 2 rigid frog utilizes a nonstandard railroad wheel flangeway. Ramps
are employed in the railroad wheel flangeways providing depths varying from not greater than
1.375 inches (34.925 mm) to not less than 0.875 inches (22.225 mm); and railroad wheel flanges
bearing is required across the area of the railway intersection.
6.1.2 Half-crossing. Where a standard gage track intersects a crane rail, two rigid frogs are
located in close proximity and are usually designed as an integral unit called a half-crossing.
6.2 Acquisition requirements. Acquisition documents must specify the following:
a. Title, number, and date of this specification.
b. Type, class, and style required (see 1.2).
c. Issue of DoDISS to be cited in the solicitation, and if required, the specific issue of
individual documents referenced (see 2.2).
d. Whether stub rails are required on switches and intended method of connecting fitting to
field rails (see table I, option 1).
e. Whether cover plates is to be hinged or bolted in place (see table I, option 2).
f. Whether stub rails are required on rigid frogs and intended method of connecting field rails
(see table II, option 1A).
g. Frog angle (of rail intersection) (see table II, option 2).
h. Whether straight or radius frog is required and radius of curvature for radius type frog
(see table II, option 3).
i. Method of connecting field rails to stub rails on turntable frogs (see table III, option 1).
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