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Track & Wheel Standards
Basic Design Dimensions for Standard Gauge
Do not be misled by the large number of decimal places in some dimensions. This does not imply an accuracy that cannot be achieved. The figures have been produced for the purposes of establishing the ScaleSeven Standards and have been calculated to a high degree of accuracy to ensure that the use of the scale ratio does not introduce undesirable distortions.
These standards are for Standard Gauge (4ft 8-1/2in). Use these links for Irish 5ft 3in gauge or GWR Brunel 7ft 0-1/4in broad gauge standards.
Dimension |
Prototype |
7mm Equivalent |
Prototype |
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Size |
Exact |
Rounded |
Equivalent (inches) |
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1 |
Track Gauge (min) |
56.5 |
32.9583 |
33.00 |
56.572 |
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2 |
Gauge Widening (max) |
0.750 |
0.4375 |
0.45 |
0.771 |
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3 |
Tyre Width |
locomotive (nom) |
5.500 |
3.2083 |
3.21 |
5.503 |
wagon and coach (min) |
5.00 |
2.9167 |
2.90 |
4.971 |
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4 |
Back-to-back (max) |
53.625 |
31.2812 |
31.30 |
53.657 |
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5 |
Effective flange |
1.125 |
0.6562 |
0.68 |
1.131 |
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6 |
Back-to-back + effective flange (4+5) |
54.750 |
31.9375 |
31.98 |
54.823 |
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7 |
Check gauge (min) |
54.750 |
31.9375 |
31.98 |
54.823 |
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8 |
Crossing flangeway (min) |
1.750 |
1.0208 |
1.00 |
1.714 |
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9 |
Over check rail faces (max) |
53.000 |
30.9166 |
31.08 |
53.280 |
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10 |
Crossing flangeway – effective flange (8–5) |
0.625 |
0.3646 |
0.32 |
0.549 |
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11 |
Check gauge – (back-to-back+one effective flange) (7–(4+5)) |
0.000 |
0.000 |
0.00 |
0.000 |
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12 |
Track gauge – (back-to-back+two effective flanges) (1–(4+(2x5))) |
0.625 |
0.3646 |
0.34 |
0.583 |
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13 |
Back-to-back – over check rail faces (4–9) |
0.625 |
0.3646 |
0.22 |
0.377 |
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14 |
Track gauge + gauge widening – (back-to-back + two effective flanges) ((1+2) – (4+(2x5))) |
1.375 |
0.8021 |
0.79 |
1.354 |
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15 |
Over tyre faces |
locomotives |
64.625 |
37.6978 |
37.67 (min) 37.77 (max) |
64.577 (min) 64.745 (max) |
wagon and coach |
63.625 |
37.1145 |
37.10 |
63.600 |
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