| When you say you are modeling in HO scale what | | | | 1:48. Even though you have these different scales in |
| does scale mean and what is the difference between | | | | the O, they all run on the same gauge of track 1.25 |
| scales and gauge? In model trains began with what | | | | inches between rails. The chart below gives you an |
| was called Carpet Railways. These were built usually | | | | idea of gauge and scale. |
| out of brass, and were basically a boiler on wheels. | | | | Gauge Designation Space Between Rails Scale |
| The boiler was filled with water and the burner was lit. | | | | (fractional equivalent) |
| The engine ran until it ran out of fuel or hit a piece of | | | | Standard ** 2.125\" (54mm) 1:24** |
| furniture sometimes turning over and spilling flaming fuel | | | | G 1.75\" (45mm) 1:22.5 or 1:20.3 |
| over the floor. These trains had no scale they were | | | | No. 11.75\" (45mm) 1:29 or 1:32 |
| whatever size the modeler made them. Electric trains | | | | O** 1.25\" (32mm)* 1:48** |
| appeared around the turn of the 20th century, but | | | | Proto-48 1.169\" (43mm) 1:48 |
| these trains still had no certain size or scale. Even after | | | | S .875\" (22.5mm) 1:64 |
| manufacturers began making commercially produced | | | | OO 3/4\" (19mm) 1:76 |
| model there was a difference between model sizes | | | | HO .650\" (16.5mm) 1:87 |
| according to the maker. It could be very frustrating to | | | | TT .471\" (12mm) 1:120 |
| buy the track and maybe the rolling stock from one | | | | N .354\" (9mm) 1:160 |
| company saying it was O scale, and buying the | | | | Z .256\" (6mm) 1:220 |
| locomotive from another manufacture as an O scale. | | | | * O gauge measures from the center of the two |
| You get the locomotive home and it would not fit your | | | | outside rails. |
| track. | | | | ** These gauges of track are used by toy trains |
| The NMRA (National Model Railroad Association) was | | | | without much attention to scale. Closest |
| formed in 1935 in the USA. They started trying to get | | | | approximations would be as shown, though they can |
| a standard set of rules set up to govern the | | | | vary quite a bit. |
| manufacturing of model trains. Also the MOROP was | | | | So you see that there is a big difference between |
| founded in Genoa Italy in 1954 that began setting | | | | scale and gauge. When you begin to model your train |
| standards for European manufacturers. The scale of a | | | | layout always make sure that the ratio is the same if |
| model is usually defined by the ratio of the model to | | | | you want everything in proportion. Especially when it |
| the real prototype. For example, Z scale in the USA | | | | comes to automobiles and other equipment you need |
| has a ratio of 1:220, with N scale being 1:160, and HO | | | | to be careful there is a great range of sizes that claim |
| scale 1:87 ratio. Even with these rules in affect there | | | | to be the same scale. Just remember the main thing |
| are still some differences in scale. In O scale the ratio | | | | about model trains scale is to always have fun |
| can range from 1:43.5 for models in Great Britain and | | | | modeling. |
| France to 1:45 in Germany and in the USA the ratio is | | | | |