Resource Guide "O" Gauge Model Trains - 1:48 Variations - Part 1

Traditional O gauge models in the U.S. are built to a scale of 1:48, or ¼ inch per foot, with a track gauge of 1¼ inch.

Tinplate.

The term ―tinplate‖ originated with trains manufactured as toys during the 1920s and 30s. Many of these early trains were made of tinplate with lithographed lettering and details. During the late 30’s most of the major manufacturers began producing much more detailed rolling stock and die cast locomotives, but the ―tinplate‖ name stuck and still is used in referring to three-rail O gauge and to American Flyer two-rail S gauge trains and their accessories.

O and O-27 three-rail tinplate.

The 27 in and O-27 refers to the 27 inch diameter of a standard circle of track. Both O-27 and O gauge track are 1¼‖ between the outside rails, but traditional O gauge track has a standard circle diameter of 31 inches and is taller and more heavily built than O-27. O-27 was originally introduced as a smaller, less expensive version of O, with undersize equipment designed to operate on tighter 27‖ diameter curves.

Nearly all O-27 equipment will run on O gauge track, but the larger O gauge cars and locomotives may not perform well through O-27 curves and switches. Most manufacturers now include several choices of

track diameter. The new Atlas line, for example, offers diameters of 27‖, 36‖, 45‖, 54‖, 63‖ and 72‖ (027, 036, 045, 054, 063, and 072). Several companies offer flexible three rail track so you can build any diameter curve you want.

Lionel, the best known producer of O and O-27 tinplate, went through a difficult period after the
founder, Lionel J. Cowen, sold his stock in 1959. Saddled with a series of owners that seemed to be
interested only in short-term profit, quality suffered along with sales and the company’s reputation.
Today, Lionel is back in the mainstream with advanced technology and a whole range of new ideas and products in addition to many old favorites.

At the same time, K-Line, MTH, Weaver, and Williams are providing some stiff competition, improving the quality of their products and offering increased value and a wider selection. Atlas, a major HO manufacturer and a one-time  producer/importer of inexpensive two rail O scale, has created a brand new company, Atlas O, devoted to developing an entirely new line of two and three-rail scale locomotives and cars, as well as railroad structures and an innovative new three-rail track system.

Louis Marx & Company stopped production of electric trains in the 1970s, but the Marx name has been revived. Ameritrains produces a specialty line of tin lithographed locomotives, cars, and train sets similar to the original tinplate products, but designed primarily for the collector. All of this activity has contributed to a surge of interest in three-rail trains, with the potential to recruit an army of youngsters who could become tomorrow’s modelers.

Hi-Rail

Hi-rail is three-rail tinplate, but with emphasis on a more realistic appearance, often including special track work  and switches, sometimes with the third rail blackened to make it less obvious. Atlas, Curtis, Gargraves, K-Line, MTH, and Ross, all manufacture this type of track. Hi rail curves are usually broader, scenery and structures are often more detailed, and a serious effort is made to keep everything closer to scale.

While some three-rail cars and engines take obvious liberties with dimensions, design, and construction to allow operation on 27‖ and 31‖ diameter curves, others are built nearly to scale with very few compromises. Many of these scale and nearly-scale-length models require more generous curves with a diameter of 54‖ or more. Imported brass models, once manufactured exclusively for two-rail in O scale, are now nearly always available in three-rail as well and may require even larger diameter curves.

O Scale

O scale uses two-rail track with scale length locomotives and cars. Few, if any, compromises are made in the design of scale rolling stock to accommodate sharp curves, so a 36‖ radius is about as tight as most O scale modelers want to go, even with short switching locomotives and older style 40’ cars.
In O scale, curvature is indicated by radius instead of diameter, which creates no end of confusion for those new to the hobby. A 36‖ (radius) curve in O scale is the same as an O72 (72‖ diameter) curve in three rail. Standard O scale wheel treads and flanges are nearly  scale size. The oversize wheels and flanges of three-rail equipment make it easier for children to manipulate and help keep the trains on the rails at high speeds. Tinplate couplers are much larger and more rugged than scale couplers and are usually mounted on the truck, providing more swing in tight curves. Scale couplers, like the prototype, are mounted on the body of the car. Track is another obvious difference. Until recently, nearly
all three-rail O gauge track was made up of rounded, tubular rail. By contrast, scale rail is solid with a shape and height that matches the prototype. O scale trains operate on 12 volts direct current (D.C.)
while three-rail uses 6 to 20 volts of alternating current (A.C.).