Editing TT scale (section)

== Standards ==
Standards useful to both manufacturers and modellers are maintained by [[MOROP]] in Europe.  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. 

TT scale locomotives are powered by [[Direct current|DC]] motors which accept a maximum of 12&nbsp;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, where the positive rail is on the right, in direction of movement. Digital train control systems have, just as in other scale, become more and more common. The most popular digital control systems used in TT scale model railways is [[Digital Command Control|NMRA-DCC]], most commonly using systems from Roco, Uhlenbrock, Kuehn, Piko or Tillig. 

There are several coupler systems used in TT. Rokal and Zeuke had simple hook-and-ring systems for their model, but these are rarely used anymore. Berliner TT Bahnen introduced a modernized coupler in the 70s, and this is still today the standard coupler on models from some manufacturers. The most common today, however, is the Tillig close-coupler system, and most ready-to-run models are equipped with this. There are also different systems for magnetic couplers, permanent couplers and so on, and some modellers also use Kadee-style couplers.

[[File:Tt-modell e 94.jpg|thumb|A DR class 94 from Berliner-TT-bahnen. The older hook-and-ring coupler is still in use by PIKO, while most other manufacturers use versions of Tillig's close-coupler]]

Most TT scale rolling stock made today is equipped with coupling pockets according to the standard NEM358, so all models have interchangeable couplings.