Lessons in the Scale, Gauge, Track and Power

The terms “O Scale” and “O Gauge” describe trains that run on 1 ¼” gauge track and are often used interchangeably. However, each term carries a different connotation of what those trains are.

“O Gauge” refers to trains that run on 1 ¼” wide 3-Rail track. The track is powered by an AC transformer, with the center rail being the power rail (positive) and the outer two rails being the grounded rail (negative). These trains tend to have “out-of-scale” or “semi-scale” proportions in order to navigate very tight curves. Such toy trains have “toy” aesthetics and are designed with durability and play value in mind (such as having stock cars hauling giraffes whose necks lower as they approach an obstacle). Toy trains take inspiration from a prototype, but are often shorter caricatures with only the minimal recognizable features, such as the Lionel 4-4-2 Atlantic (loosely based off of the NYC Hudsons), which was a staple of their starter sets. They can also be based on a prototype, such as the O-27 version of the Pennsylvania Railroad GG1 (as seen below).

Toy trains can have out of scale details, such as thick pipe detail and metal bodies with cast-in details. They can also include designs that are entirely fictitious with fantasy paint schemes. O Gauge trains have oversized couplers and large flanges on the wheels that are designed to run on oversized rails (tubular rail or enlarged “I-Beam” rail) at high speeds often in excess of 80 scale MPH. Such toy trains are a great place to start, and some adults continue in 3-Rail. However, the limitations for true prototypical operations are obvious.

“O Scale” refers to trains that are modeled in one quarter inch to the foot (1:48) and run on 2-Rail track. The track is either powered by a DC power pack, or Digital Command Control electronics, with either rail being positively or negatively charged, so long as opposing rails are opposite charges. Sometimes, the track isn’t powered at all; this is called Dead Rail (Power Onboard Radio Control). In O Scale, every model (the trains, track and approach to layout design) are generally based on a prototype. Such models are finely detailed and are true scale representations of their prototypical counterparts. Design compromises seen on 3-Rail locomotives are not features on scale models (ex. swinging pilots, thick flanges and wheels, construction with durability in mind and oversized couplers). Scale models are built from prototype blueprints and photographs. While every scale reproduction requires some compromises, scale modelers attempt to reproduce the prototype as accurately as possible in miniature (as seen below).

The contrast between scale models and toy trains is dramatic in O. Lionel, MTH, Williams, K-Line and other manufacturers make a variety of toy trains. These sturdy toys are terrific to get started with model trains. While there are some exceptions to this description, this is the most basic distinction between O Gauge and O Scale. This is not to “knock” or “dismiss” people who enjoy the 3-Rail segment of the hobby; many an O Scaler get their start with 3-Rail toy trains. This is simply to describe the differences between those who scale model and those who have an interest in classic toy trains. One is not better than the other, one is simply more realistic.