The technology used in making model trains run has evolved over time. In the beginning model trains were completely stationary, but then innovations gave way to push along model trains such as the Airfix and Lone Star models. After this came the model trains that could be run automatically using different kinds of powering methods.
The early model trains employed clockwork in their mechanisms. The locomotives were controlled by levers, but the disadvantage was that this made the method of control slightly crude. Nonetheless, the large scale models in which this technology was used were deemed as practical, and after some time, manufacturers were also able to slow down and stop trains at stations through multiple levers.
The industrial revolution gave way to model trains being powered by live steam. This method was often used in model trains that were constructed in gauges of 5 and 7 ½ inches and were run outdoors. Live steam model strain have also been built in scales of HO, OO and N. In Australia, Z scale model trains that run on live steam are still manufactured.
Nowadays, electricity is being used as the prime way to power model trains. Though most companies use direct current that is supplied through the rail tracks, some companies like Lionel and Marklin use alternating current.
A three-rail system was used in the early electrical models. Metal sleepers on the outer tracks conducted power and the middle track provided this power to the locomotive in order to make it skid along. Since the models at that time were made of metal, conductivity issues were not a problem. Sometimes, metal studs were used in place of the center track to make it more realistic. However, the use of metals in the manufacture of these locomotives did make them bulky and heavy and then there was also the issue of insulation and safety hazards. A variation that came of being as a result of these issues was the two-rail model tracks. In these, the wheels were kept separate from one another and the rails carried along the negative or positive power supply.
Another method of powering model trains is using overhead line. This allows the control of two trains on the same track. One train would be supplied power through the over head wire cable and the other would be supplied power through the running rail tracks.
Batteries are a more hassle free and safe method of powering model trains. These were initially used in the late 19th century and at the start of the 2th century because at that time, not many homes has electricity supplied to them. Internal rechargeable batteries can also be used so do away with the worry of having to constantly replace worn out batteries. Often, large scale battery powered model trains are controlled by radio.
Sometimes, companies such as Pilgrim Locomotive Works sell locomotives that draw inspiration from diesel-electric model trains. Model trains that run on internal combustion engines, as well as petrol-hydraulic versions are unusual and thus more expensive than the readily available electrically powered model trains.