N scale is a popular model railway scale/track gauge. Depending upon the manufacturer (or country), the scale ranges from 1:148 to 1:160. In all cases, the gauge (the distance between the rails) is 9 mm. The term N gauge refers to the track dimensions, but in the UK in particular N gauge refers to their 1:148 scale, 9 mm track gauge modeling. The terms N scale and N gauge are often used interchangeably. An advantage of N scale is that it allows hobbyists to build layouts that take up less space than HO scale, or put longer track runs into the same amount of space, because the models are smaller (by nearly a half) than they are in HO scale (1:87). The name comes from an abbreviation for Nine millimetres, which is the distance between the inside edges of the rails. N scale however, is not the smallest commercially available scale, as Z scale is smaller yet at 1:220.
Although trains and accessories of similar gauge and/or scale existed as early as 1927, modern commercially produced N scale models only appeared in 1962. Unlike other scales and gauges, which were de facto standards at best, within two years N scale manufacturers defined the gauge, voltage, as well as the height and type of couplers.
N scale has a large worldwide following. Models are made of very many standard gauge prototypes from every continent. N scale's popularity is second only to HO scale's. In Japan, where space in homes is more limited, N scale is the most popular scale, and HO scale is considered large. Not all modellers select N because they have small spaces, some use N scale in order to build more complex or more visually expansive models.
N scale in Australia has become more popular over the years, with modellers modelling mainly US, British and European prototypes, and until recently, the Australian market has had no N scale models of local prototype, which is now a flourishing "cottage" industry, Australia N scale modelling becoming more popular each year.
N gauge track and components are also used with larger scales, in particular HOe and OO9 scale for modelling narrow gauge railways. N scale models on Z scale track are used to model metre gauge (Nn3). A small amount of 2' industrial narrow gauge modelling in N scale using custom track is done but there are few suppliers of parts. And N scale trains and structures are often used on HO or larger layouts to create forced perspective, or the illusion that an object is further away than it actually is.
Standards useful to both manufacturers and modellers are maintained by MOROP in Europe and the NMRA in North America. These standards are generally the same for such elements as track gauge, scale ratio, couplings, and electrical power and differ for clearances and other factors that are specific to the prototype being modelled.
N scale locomotives are powered by DC motors which accept a nominal maximum of 12 V DC. In traditional DC control, the speed of the train is determined by the amount of voltage supplied to the rails. The direction of the train is determined by the polarity of the power to the rails. Since the end of the 20th century, an increasing number of enthusiasts have started using Digital Command Control (DCC) to determine the speed and direction of their trains. This has in part been made possible by surface mount technology and new motors that draw very little current (typically 0.2amps).
The initial agreed-to standard coupling is known as a 'Rapido' coupler from the manufacturer (Arnold). Most companies developed their own variants of this coupler to avoid Arnold patents on the spring system. Graham Farish initially adopted a plastic flexible U rather than a spring, Peco used a compatible weighted coupler system (Elsie) and Fleischmann cunningly sidestepped the problem by using a sprung plate. All however were compatible.
The Rapido coupler system works well but is difficult to use for automatic uncoupling and also relatively large. U.S., Canadian and Australian modellers are making more and more use of a more realistic looking proprietary coupler system, available from Micro-Trains Line Co.. The MT couplers (as they are known) are more delicate and closer to scale North American appearance than Rapido couplers. Other manufacturers are now making couplers that mate with Micro Trains couplers although without all the features of the MT couplers due to MTL owned patent rights.
European modellers have the option to convert the couplings on their rolling stock to the Fleischmann Profi-Coupler system for more reliable operation should they wish to do so, but most N scale rolling stock continues to be manufactured with Rapido couplers - a design which is fairly robust and easy to mold. Modern N scale stock uses a standard NEM socket for couplers which allows different coupling designs to be used by simply pulling out the old coupler and fitting a new one of a different design.
In the United States and Europe, models of standard gauge (4ft 8.5in) trains are built to 1:160 scale and made so that they run on N gauge track, but in some other countries changes are made. Finescale modellers also use variants of normal N scale.
In the United Kingdom a scale of 1:148 is used for commercially produced models. In Japan, a scale of 1:150 is used for the models of 3 ft 6 in gauge trains, while a scale of 1:160 is used for models of standard gauge Shinkansen (Bullet Train) models. In the U.S. and Europe, a scale of 1:160 is used for models of trains, irrespective of the gauge of the real trains they are scaled from. All of these scales run on the same 9mm track gauge (N gauge). This means the track is a little too narrow for 1:148/1:150 but the difference is usually considered too small to matter. Strict 2mm fine scale modellers use slightly wider and usually hand built track.
In Britain, some N scale models are built to "2 mm scale" for "2 mm to the foot" which calculates to a 1:152 proportion. Early N scale was also known as "OOO" or "Treble-O" in reference to O and 00 and was also 1:152, though for an entirely different reason.
Electrified models followed soon after. The track gauge was widened to a nominal 9 mm and rails were isolated with non-conductive ties (sleepers) for DC operation. A different coupling based on a shrunken OO scale coupling was fitted. The OOO couplings and specifications have long since been replaced by commercial N scale manufacturers.
Most models come out of the packaging looking brand new. Most real trains however, are affected in some way by the weather from the moment they are rolled out of the paint-shop. After even a short period of time, most real trains become very dirty, especially if they are not subjected to a regular cleaning schedule. For many years model train enthusiasts have been detailing their locomotives and rolling stock to look like real trains, and this includes adding the accumulation of dirt and grime that can be seen on real trains. Weathering makes the tiny details on N scale models more visible and makes the models seem more "real" to the casual observer.