MIL-DTL-82020C(YD)
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 D, 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
(48 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 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 non-standard railroad wheel flangeway ramps are
employed in the railroad wheel flangeways providing depths varying from not greater than
1.375 inches (35 mm) to not less than 0.875 inches (22 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. When stub rails shall not be cast with holes in the web for joint bar installation (see 3.1).
e. Number of pieces switch is to be cast (see table I, option 1).
f. If switch shall be provided with cover plates (see table I, option 2).
g. If the switch pivot pin shall be provided with bronze pivot bushing (see table I, option 3).
h. Whether switch throw mechanisms shall be power or manually operated (see table I,
option 4).
i. If stub rails are required on frogs and intended method of connection of stub rails or field
rails to base plate (see table II, option 1).
j. Frog angle (angle of track intersection) (see table II, option 2).
k. Whether straight frog or radius frog is required and radius of curvature of radius type frog
(see table II, option 3).
l. If half-crossings are to be provided with double flangeway extension and method of
attachment of extension of each base plate (see 3.1.3 and table II, option 4).
m. When track connection points are provided with bolt holes for bolted connection to tracks
or with ends beveled for arc welding (see 3.1.3).
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