2_gauge References

2 gauge
2 gauge
Scale ratio	ca. 1:22.5
Model gauge	64 mm (2+1⁄2 in); later: 2 in (50.8 mm)
Prototype gauge	1,435 mm (4 ft 8+1⁄2 in) standard gauge

Gauge 2 (also called 2 gauge or II gauge) is a model railway gauge, originally 64 mm (2+1⁄2 in),^[1] then standardised in 1909 at 2 in (50.8 mm), a 20% reduction and a change in definition: from mm to inch.^{[
citation needed]} It has since fallen into disuse. The gauge was introduced by Märklin at the Leipzig toy fair in 1891. Gauge 2 was equivalent to a 1:22.5 scale.

Related scales and gauges

After the change to 2 in (50.8 mm) in 1909, 64 mm (2+1⁄2 in) gauge was standardised as 3 gauge (or III gauge).

European G gauge trains are built to the same II gauge scale, but with a narrow rail gauge of 45 mm (1.772 in) (the same as 1 gauge). This G gauge at 1:22.5 scale represents 1,000 mm (3 ft 3+3⁄8 in) metre gauge narrow-gauge railways. This scale-gauge combination is sometimes called IIm in European literature.

In the UK, Gauge 2 was 2 inches (50.8 mm) while Gauge 3 was 2+1⁄2 in (64 mm). From this, it follows that G gauge is sometimes, albeit rarely, referred to as 3m. A 2 inch (50.8 mm) gauge of standard gauge locos gives a scale of 1:28.25, not so far off the 1/29 used by some manufactures with 45 mm (1.772 in) gauge track. In the grand tradition of model rail gauges often being narrower than the full scale equivalent ( 00 scale being the classic example) this is deemed perfectly acceptable.