Railway modelling has long used a variety of scales and gauges to represent its models of real subjects. In most cases, gauge and scale are chosen together, so as to represent Stephenson standard gauge. By choosing a smaller gauge than this for a particular scale, the model represents a narrow-gauge example.[1][2]
Such gauge and scale combinations are of course used for the deliberate modelling of particular narrow-gauge subjects, where the choice of subject is behind the choice of combination. Narrow-gauge modelling has also become especially popular from the purely modelling aspects: it combines a conveniently visible large scale that is easier to work on, with a narrow model gauge that allows tighter radius curves and so fits layouts into smaller spaces. This has been a particular reason in Europe where, houses being generally smaller than in the US, there is rarely space for 0 gauge and even 00 gauge is restricted in the size of curves.
At times, particularly in the early days before the inertia of popular scales developed, modellers would choose seemingly random scales in order to model a particular prototype and its original gauge whilst using a readily available gauge.[3] As the range of commercial products increases, both for gauges and scales, it is easier to find a combination that is already supported and so there is less need to scratch-build everything.[1]
Namingedit
Naming of these gauge and scale combinations follows a few broad rules, but not always consistently. Some, such as G gauge and SM32 were defined from the outset as narrow-gauge scales and so have a single component to their name.
Britishedit
Many names, particularly those of British origin, such as O14 and 00-9 combine the name of the scale used with the physical measurement of the gauge, i.e. the 7mm to the foot scale from standard O gauge with a rail gauge of 14mm, giving a precise representation of 2 ft (610 mm) prototypes. As it is the scale that controls interoperability between models and also the manufacture of non-railway scenery etc., it is the scale rather than the gauge that takes the primary position in names.
Europeanedit
MOROP, the European model railway standards organisation, issues standards documents called NEMs . NEM010 defines the main model railway gauges, including narrow gauges.[2] Unusually, unlike the British model railway trade, this recognised narrow-gauge modelling from the outset. This may be because of Europe's greater prototypical use of the larger narrow gauges for smaller branch lines.
NEM010 defines and names narrow gauges for all the supported scales although it takes a broad approach and groups the prototypes into 'nominal size' ranges or 'Nenngröße'. It defines these prototype gauge ranges as:[2]
Names are of the form 'H0e gauge', comparable to 00-9, as 'Narrow gauge in H0 scale'. Thus the scale and approximate prototype gauge are represented, with the model gauge used (9mm for H0e gauge; 6.5mm for H0f gauge) being implied.[2]
The scales used include the general European modelling range of Z, N, TT, H0, 0 and also the large model engineering gauges of I to X, including 31⁄2", 5", 71⁄4" and 101⁄4" gauge. As 00 is a particularly British scale, it is not included within this pan European standard. However the predominantly US imperial-based S scale (1:64) does feature.
United Statesedit
US gauges are named as On30 or Sn3, composed of the scale, 'n' for narrow gauge and the dimensions of the prototype gauge being modelled. These are universally in imperial units rather than metric, but there is no consistency between using inches or feet. Both On42 and On2 are used, but when referring to the prototype gauge, e.g. On30 / On21⁄2, the gauge is usually given in inches.
^ abOn42 – 7mm S7 scale used for Richard Chown's[14] Fangfoss,[15][16] Norwegian 3 ft 6 in (1,067 mm). 1:48 1⁄4" scale used for Queenslandsugar cane railways[17] and US subjects[18] of 3 ft 6 in (1,067 mm)
^On3 – Using US O scale (1:48 ratio) with 0.75 in gauge track to represent 3 ft (914 mm). Probably the second most popular US scale for 3 ft (914 mm).
^On30 – 1:48 scale with 16.5 mm track to represent 2 ft 6 in (762 mm), in practice anything between 2 ft (610 mm) and 3 ft (914 mm). On21⁄2 is another name for the same standard. Commercial support, particularly from Bachmann, is available.
^On2 – Precise modelling of USA 2ft gauge using 1:48 O scale and a unique 12.7 mm gauge. This may be considered a Finescale version of On30. There is little to no commercial support for the mechanical aspects of this unique gauge but it is sometimes possible to re-use or re-gauge commercial models for On30.
^On20 – Extremely rare gauge primarily for modeling 20" mining railroads in the USA
^Pempoul – Finescale modelling of French metre gauge at 1:50 scale on 18.2 mm Finescale EM gauge. So far only used by Gordon & Maggie Gravett.[22][23]
^Towy Valley Tramway – Finescale modelling of 2ftt gauge on 12mm.[24]
^ ab5.5 mm – Used to represent both 3 ft (914 mm) (on 16.5mm) & 2 ft (610 mm) (on 12mm) gauges. British outline two foot gauge[25] is one of the oldest narrow gauge modelling scales, when the GEM company in 1963 launched white metal kits to represent Welsh slate railways, using readily available TT gauge parts. Three foot gauge in this scale is mostly US[26] and has little in common with the two foot.
^HOn3 – Using HO scale (1:87 ratio) with 10.5 mm gauge track. Historically the most popular of the scale/gauge combinations for modelling 3 ft gauge in the USA.
^H0f (H0i) – 1:87 6.5 mm (Z gauge) 400 to 650 mm; Continental European.
^HOn2 – 1:87 7 millimetres (0.276 in) 2 ft (610 mm) American
^TTn3 – 3 mm scale on 9 mm gauge to model 3ft prototypes. Some use in Australasia at TTn31⁄2 for their 3 ft 6 in (1,067 mm) lines, and known as NZ120 in New Zealand[27]
Wikimedia Commons has media related to Model railway scales.
^UK O gauge uses a scale of 7mm/foot, Europe uses 1:45 and the US 1:48
^T gauge is a constant 3 mm gauge, although it defines two scale standards: 1:480 for modelling Stephenson gauge and 1:450 for Japanese 3 ft 6 in (1,067 mm).
Referencesedit
^ abc"Modelling the Narrow Gauge". The 7mm Narrow Gauge Association.
^ abcdefghi"Normen Europäischer Modellbahnen Maßstäbe, Nenngrößen, Spurweiten" (PDF) (in German). NEM. 2011. Retrieved 2014-05-15.
^Cyril R. Burch (March 1963). "Building Glyn Valley Tramway coaches". Narrow Gauge Journal. Ynys Gwyntog. 1. (6).
^Gauge is defined by NEM 010, but not as a standard gauge for any scale.