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RP-12.3 Turnout Dimensions

HO Scale

RP-12.3

Turnout Diagram

Look here for a larger printable copy of this diagram.

Original Calculation by E. R. Frase
New Design by Clarence H. Hill

Jump to Frog Numbers 8, 9, & 10.

(1) FROG NUMBERS 4 5 6 7
PROPERTIES OF CURVED SWITCHES
(2) Rail Length 2-1/8" 2-1/8" 2-1/8" 3-3/16"
(3) Point Angle * 2d 01' 2d 01' 2d 01' 1d 20'
(4) Heel Spread [+] 1/8" 1/8" 1/8" 1/8"
(5) Heel Angle * 4d 51' 4d 51' 4d 51' 2d 53'
(6) Switch Radius 43" 43" 43" 117"
(7) Mid-Ordinate .013" .013" .013" .011"
LEAD TO THEORETICAL POINT OF FROG
(8) Lead 5-1/16" 5-11/16" 6-1/4" 8-7/16"
CLOSURE DISTANCE
(9) Straight Rail 2-3/8" 2-15/16" 3-7/16" 4-1/2"
(10) Curved (Length) 2-7/16" 2-31/32" 3-15/32" 4-17/32"
(11) Rail (Radius) 15" 26" 43" 49"
GAGE LINE OFFSETS ON CURVED CLOSURE RAIL
(12) 1st Point Y1 [+] 15/64"
(13) 1st Point X1 4-7/8"
(14) Mid-Point Y2 [+] 19/64" 19/64" 19/64"
(15) Mid-Point X2 3-1/2" 3-5/8" 3-3/4"
(16) 3rd Point Y3 [+] 3/8"
(17) 3rd Point X3 6-1/4"
PROPERTIES OF FROGS
(18) Frog Angle * 14d 15' 11d 25' 9d 32' 8d 10'
(19) Overall Length 1-1/2" 1-11/16" 1-7/8" 2-1/16"
(20) Toe Length 9/16" 5/8" 11/16" 3/4"
(21) Heel Length 15/16" 1-1/16" 1-3/16" 1-5/16"
(22) Toe Spread 9/64" 1/8" 7/64" 7/64"
(23) Heel Spread 15/64" 7/32" 13/64" 3/16"
POINT OF FROG TO INTERSECTION OF CENTER LINES
(24) PF to ICL 2-19/32" 3-1/4" 3-29/32" 4-9/16"
DATA FOR CROSSOVERS -- PF to PF ON PARALLEL TRACKS
Distance for 2" Track Centers Along:
(25) Straight Track 2-11/16" 3-3/8" 4-1/8" 4-13/16"
(26) Crossover Track 2-15/16" 3-5/8" 4-1/4" 4-15/16"
Increment for 1/8" Change in Track Centers Along:
Straight Track 1/2" 5/8" 3/4" 7/8"
Crossover Track 1/2" 5/8" 3/4" 7/8"

Return to Frog Numbers 4, 5, 6, 7

(1) FROG NUMBERS 8 9 10
PROPERTIES OF CURVED SWITCHES
(2) Rail Length 3-3/16" 3-3/16" 3-3/16"
(3) Point Angle * 1d 20' 1d 20' 1d 20'
(4) Heel Spread [+] 1/8" 1/8" 1/8"
(5) Heel Angle * 2d 53' 2d 53' 2d 53'
(6) Switch Radius 117" 117" 117"
(7) Mid-Ordinate .011" .011" .011"
LEAD TO THEORETICAL POINT OF FROG
(8) Lead 9" 9-9/16" 10-1/16"
CLOSURE DISTANCE
(9) Straight Rail 4-15/16" 5-3/8" 5-3/4"
(10) Curved (Length) 4-31/32" 5-13/32" 5-25/32"
(11) Rail (Radius) 67" 89" 117"
GAGE LINE OFFSETS ON CURVED CLOSURE RAIL
(12) 1st Point Y1 [+] 15/64" 15/64" 15/64"
(13) 1st Point X1 4-15/16" 5" 5-1/16"
(14) Mid-Point Y2 [+]
(15) Mid-Point X2
(16) 3rd Point Y3 [+] 3/8" 3/8" 3/8"
(17) 3rd Point X3 6-1/2" 6-3/4" 6-15/16"
PROPERTIES OF FROGS
(18) Frog Angle * 7d 09' 6d 22' 5d 43'
(19) Overall Length 2-3/8" 2-11/16" 3"
(20) Toe Length 7/8" 1" 1-1/8"
(21) Heel Length 1-1/2" 1-11/16" 1-7/8"
(22) Toe Spread 7/64" 7/64" 7/64"
(23) Heel Spread 3/16" 3/16" 3/16"
POINT OF FROG TO INTERSECTION OF CENTER LINES
(24) PF to ICL 5-3/16" 5-27/32" 6-1/2"
DATA FOR CROSSOVERS -- PF to PF ON PARALLEL TRACKS
Distance for 2" Track Centers Along:
(25) Straight Track 5-9/16" 6-1/4" 6-15/16"
(26) Crossover Track 5-11/16" 6-3/8" 7-1/16"
Increment for 1/8" Change in Track Centers Along:
Straight Track 1" 1-1/8" 1-1/4"
Crossover Track 1" 1-1/8" 1-1/4"

* the d stands for degrees (2d 01' is 2 degrees 01 minutes)

NOTES:
a. Recommended to use gages for dimensions marked [+]
b. Switch heel joints should not be out of square more than 1/32".
c. Refer to RP-15.1 for suitable rails.
d. Slip-on joint bars may be used up to 7/16" long and B&S gage No. 30 thick. The fit must be snug on the base of the rail. At the heel of the switch it may be necessary to cut away a portion of the stock rail base.

Return to Frog Numbers 4, 5, 6, 7 or 8, 9, & 10.