EM gauge
Encyclopedia
EM gauge is a variant of 4 mm to a foot (1:76) scale used in model railways.
EM was developed because OO gauge
, favoured by manufacturers of British prototype models, utilised track that was too narrow. OO was developed in the UK in the 1930s as a response to manufacturers finding they were unable to fit the motors of the time into British prototype small boilered locomotives when scaled at the globally popular HO scale
's 3.5 mm to a foot (1:87). As the scale was increased to 4 mm to the foot to make the locomotives larger, the track gauge was left at , and hence is too narrow (by a scale 178 mm (7 in)) to correctly depict the prototype's track gauge
of .
EM gauge was founded in the 1950s, originally with gauge track and rolling stock
wheelsets based upon the crude and massively out-of-scale products of the contemporary OO model manufacturers.
Since then wheelset standards have become more fine, allowing EM to evolve into gauge track (for a while called EEM gauge until it was adopted into the mainstream standard). Some modellers were still not happy with this, it is still a scale 1.9 inches (48.26 mm) too narrow, and developed P4 scale
standard ( gauge).
Most EM modellers will have started off using OO gauge and having acquired the necessary modelling skills, then advanced into EM. Modellers in EM typically re-wheel their rolling stock and hand-build their trackwork, although pre-built track is available from specialist suppliers. There are also many 4 mm scale kits which can be used by all 4 mm scale gauges, and since the advanced skills, advanced kitbuilding and scratchbuilding are also common.
EM standards are set by the EM Gauge Society, defining gauge and wheel dimensions to ensure compatibility across layouts.
EM was developed because OO gauge
OO gauge
OO gauge or OO scale model railways are the most popular standard-gauge model railway tracks in the U.K. This track gauge is one of several 4mm-scale standards used, but it is the only one to be served by the major manufacturers...
, favoured by manufacturers of British prototype models, utilised track that was too narrow. OO was developed in the UK in the 1930s as a response to manufacturers finding they were unable to fit the motors of the time into British prototype small boilered locomotives when scaled at the globally popular HO scale
HO scale
HO or H0 is the most popular scale of model railway in the world.According to the NMRA standard S-1.2 predominantly used in North America, in HO scale, represents 1 real foot ; this ratio works out to about 1:87.1. According to the MOROP standard NEM 010 predominantly used in Europe, the scale is...
's 3.5 mm to a foot (1:87). As the scale was increased to 4 mm to the foot to make the locomotives larger, the track gauge was left at , and hence is too narrow (by a scale 178 mm (7 in)) to correctly depict the prototype's track gauge
Rail gauge
Track gauge or rail gauge is the distance between the inner sides of the heads of the two load bearing rails that make up a single railway line. Sixty percent of the world's railways use a standard gauge of . Wider gauges are called broad gauge; smaller gauges, narrow gauge. Break-of-gauge refers...
of .
EM gauge was founded in the 1950s, originally with gauge track and rolling stock
Rolling stock
Rolling stock comprises all the vehicles that move on a railway. It usually includes both powered and unpowered vehicles, for example locomotives, railroad cars, coaches and wagons...
wheelsets based upon the crude and massively out-of-scale products of the contemporary OO model manufacturers.
Since then wheelset standards have become more fine, allowing EM to evolve into gauge track (for a while called EEM gauge until it was adopted into the mainstream standard). Some modellers were still not happy with this, it is still a scale 1.9 inches (48.26 mm) too narrow, and developed P4 scale
P4 gauge
P4 or Protofour is a set of standards for model railways allowing a more accurate construction of models to a scale of 4 mm to 1 foot , the predominant scale of model railways of the British prototype...
standard ( gauge).
Most EM modellers will have started off using OO gauge and having acquired the necessary modelling skills, then advanced into EM. Modellers in EM typically re-wheel their rolling stock and hand-build their trackwork, although pre-built track is available from specialist suppliers. There are also many 4 mm scale kits which can be used by all 4 mm scale gauges, and since the advanced skills, advanced kitbuilding and scratchbuilding are also common.
EM standards are set by the EM Gauge Society, defining gauge and wheel dimensions to ensure compatibility across layouts.