MIL-DTL-82020C(YD)
2.3 Order of precedence. In the event of a conflict between the text of this document and the
references cited herein, the text of this document takes precedence. Nothing in this document,
however, supersedes applicable laws and regulations unless a specific exemption has been
obtained.
3. REQUIREMENTS
3.1 Description. Track fittings shall be as specified herein and shown on NAVFAC drawings
1294420 through 1294422 and 1403326 through 1403330. The equipment specified herein are
specially designed items intended for specific application to portal crane tracks. Unless otherwise
specified (see 6.2), all stub rails shall be cast with holes in the web for joint bar installation.
Examples of various applications of equipment covered by this document are shown in figure 1.
3.1.1 Double tongue track switch. The double tongue switch consists of a cast manganese steel
switch bed supporting a cast manganese steel switch tongue with two rails. These provide a
flangeway on both the gage side and the field side of the running rails, in either operating position.
The switch tongue shall be curved for turnout to the right for class A, or to the left for class B
(see 1.2). The double tongue switch shall be constructed to provide adequate drainage to prevent
ponding of rainwater. Additional options for track switches are listed in table I and depicted on
NAVFAC drawings 1403326 and 1403327.
TABLE I. Options for double tongue track switch (see 6.2).
Option
Choose
Description
Number
one
1
A
One piece casting
B
Two piece casting
C
Three piece casting
2
A
With cover piece
B
Without cover piece
3
A
With bronze pivot bearing
B
Without bronze pivot bearing
4
A
With manually operated throw mechanism
B
With power operated throw mechanism (manual override capability
required)
3.1.2 Rigid frogs. The rigid frogs consist of a one-piece casting of manganese steel. Class C is
designed with two double flangeways for the intersection of two rails. Class D is designed with a
double flangeway for one rail and a single flangeway for the other. This accommodates the
intersection of a crane rail with a standard gage railroad rail. Additional options for rigid frogs
are listed in table II and depicted on NAVFAC drawings 1403328 and 1403330.
4
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