Model Trains aren't just kids' toys. There are some very serious train hobbyists out there. Their involvement ranges from possession of a single train set to spending hours upon hours and large sums on a substantial and exacting models of a railroads and the scenery through which it passes, called a "layout". These hobbyists, called "railway modelers" or "model railroaders", may maintain models large enough to ride on (Garden Railroading). Modelers may collect model trains, building a landscape for the trains to pass through, or operate their own railroad in miniature.
Layout complexity may vary from a simple circle or oval track to realistic reproductions of real places modeled to scale. To enhance their knowledge and experiences, these serious hobbyists gather at model railroad clubs where they talk the talk and walk the walk of model railroad engineers. These clubs often display models for the public. Young and old love these exhibits. The large scale (garden variety) models are usually hand-built and powered by live steam, or diesel-hydraulic, and the engines are often powerful enough to haul dozens of human passengers. Railways of this size are also called miniature railways.
Scales and gauges
The size of locomotive engines depends on the scale and can vary from 700 mm (27.6 in) tall for the largest ridable live steam scales such as 1:8, down to matchbox size for the smallest in Z-scale (1:220). Recently, another scale that was introduced that is also commercially available, called T Gauge, it is 3 mm (0.118 in) gauge track and is a scale of 1:450, basically half the size of Z scale. A typical HO (1:87) engine is 50 mm (1.97 in) tall, and 100 to 300 mm (3.94 to 11.81 in) long. The most popular scales are: G gauge, Gauge 1, O gauge, S scale, HO gauge (in Britain, the similar OO), TT scale, and N scale (1:160 in the United States, but 1:144 in the UK). There is growing interest in Z scale and T Gauge. HO and OO are the most popular. Popular narrow-gauge scales include Sn3, HOn3 Scale and Nn3, which are the same in scale as S, HO and N except with a narrower spacing between the tracks (in these examples, a scale 3 ft (914 mm) instead of the 4 ft 8 1⁄2 in (1,435 mm) standard gauge).
The largest common scale is 1:8, with 1:4 sometimes used for park rides. G scale (Garden, 1:24scale) is most popular for backyard modeling. It is easier to fit a G scale model into a garden and keep scenery proportional to the trains. Gauge 1 and Gauge 3 are also popular for gardens. O, S, HO, and N gauge are more often used indoors. Lionel trains in O scale (1:48scale) are popular toys. S refers to 1:64 scale.
The words scale and gauge seem at first interchangeable but their meanings are different. Scale is the model's measurement as a proportion to the original, while gauge is the measurement between the rails. Your choice of scale has a lot to do with budget and available space. N-Scale is a popular apartment size scale. The key is to stick to your choice once you have decided on a scale, and not mix scales in a single layout.
Couplers and connectors
In addition to different scales, there are also different types of couplers for connecting cars, which are not compatible with each other.
In H0, the Americans standardized on horn-hook or X2F couplers, though these have largely given way to working knuckle couplers which are a close approximation to the "automatic" couplers used on the prototype there and elsewhere. Also in H0, the European manufacturers have standardized, but on a coupler mount, not a coupler: many varieties of coupler can be plugged in (and out) of the NEM coupler box. None of the popular couplers has any resemblance to the prototype three-link chains generally used on the continent.
For British modelers, whose most popular scale is 00, the normal coupler is a tension-lock coupler, which again has no pretense of replicating the usual prototype three-link chain couplers. Bachmann and more recently Hornby have begun to offer models fitted with NEM coupler pockets. This theoretically enables modelers of British railways to substitute any other NEM362 coupler, though many Bachmann models place the coupler pocket at the wrong height. A fairly common alternative is to use representations of chain couplings as found on the prototype, though these require large radius curves to be used to avoid derailments.
Other scales have similar ranges of non-compatible couplers available.
Power Sources
Model railway engines are generally operated by low voltage direct current (DC) electricity supplied via the tracks, but there are exceptions, such as Mrklin and Lionel Corporation, which use alternating current (AC). Modern Digital Command Control (DCC) systems use alternating current. Other locomotives, particularly large models, used steam. Steam or clockwork driven engines are still sought by collectors.
Clockwork
Most early models for the toy market were powered by clockwork and controlled by levers on the locomotive. Although this made control crude the models were large and robust enough that grabbing the controls was practical. Various manufacturers introduced slowing and stopping tracks that could trigger levers on the locomotive and allow station stops.
Electricity
Three-rail
Early electrical models used a three-rail system with the wheels resting on a metal track with metal sleepers that conducted power and a middle rail which provided power to a skid under the locomotive. This made sense at the time as models were metal and conductive. Modern plastics were not available and insulation was a problem. In addition the notion of accurate models had yet to evolve and toy trains and track were crude tinplate. A variation on the three-rail system, Trix Twin, allowed two trains to be independently controlled on one track, before the advent of Digital Command Control.
