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MRP-1.1 Narrow Gauge, Modules
Recommended Practices are only less mandatory than Standards by virtue of their slightly less critical subject matter and/or the fact that deviation for specific reason is permissible.
(*)denotes change from previous issue.
| Scale | Parallel Tangent Track Length | Maximum Mainline Grade | Minimum Mainline Turnout | Minimum Mainline Radius** |
|---|---|---|---|---|
| Zn3 | 3-1/4" (82.6mm) | 4% | #4 | 5" (127mm) (1.) |
| Nn3 | 4" (101.6mm) | 4% | (*)#4 | 7-1/2"(196mm) |
| HOn2 | 3" (76.2mm) | 4% | #6 | 18" (457.2mm) |
| HOn 2-1/2 | 3-1/2" (88.9mm) | 4% | #6 | 20" (508mm) |
| HOn3 | 3-1/2" (88.9mm) | 4% | #6 | 20" (508mm) |
| Sn2 | 3-5/8" (92.1 mm) | 4% | #6 | 27" (685.8mm) |
| Sn2-1/2 | 3-5/8" (92.1 mm) | 4% | #6 | 31" (787.4mm) |
| Sn3 | 3-5/8" (92.1 mm) | 4% | #6 | 31" (787.4mm) |
| On2 | 3-3/4" (95.2mm) | 4% | #6 | 40" (1016mm) |
| On2-1/2 | 3-3/4" (95.2mm) | 4% | #6 | 30" (762mm) |
| On3 | 3-3/4" (95.2mm) | 4% | #6 | 42" (1066.8mm) |
MODULE WIDTH FOR ALL SCALES EXCEPT Nn3 should be 24" MINIMUM, 36" MAXIMUM: Nn3 should be 1'-4" unless dual gauge, i.e., standard N gauge in front, at which time standard N gauge width of 24" minimum, 36" maximum should apply.
RECOMMENDED PRACTICES FOR ALL SCALE, ITEMS 2-11, WILL ALSO APPLY TO NARROW GAUGE. PLEASE SEE MRP-1 FOR ADDITIONAL RECOMMENDED PRACTICES.
** Larger radius permissible.
(1.) Zn3 is not available at this time. Figures included for possible future use.