Types of locomotives
Prototype steam engines were used for about 130 years, from the first railroads in the 1830s until the early 1960s. The first diesels appeared in the early 1930s and operated side-by-side with steamers on many railroads during the 1940s and early 1950s.
A wide variety of plastic and metal locomotive models is available today. These are generally offered as either ready-to-run models or as kits and are available in various scales. For steam engines, you can find models representing prototype engines built between 1870 and the 1940s. Diesel locomotives continue to be built, and highly detailed models of engines past and current are available from a number of manufacturers.
Electric locomotives were operated in the busy Northeast Corridor from Washington, D.C., to Boston, as well as on some mountain lines. Models of electric locomotives are also available.
Can and open-frame motors
The most common power source used in model locomotives is the can motor. These motors are completely enclosed and have a ring magnet that surrounds the armature. Can motors have smooth running characteristics and require a low current draw.
Older models will often have open-frame motors. On this type of motor the magnet is mounted at one end with iron pole pieces extending to each side of the armature. The armature is visible from the sides, giving the motor the open-frame name. While these motors operate well, they don't start as smoothly as can motors do, and they draw two to three times more current.
The magnetic knuckle coupler, as pioneered by Kadee, is the most widely used model railroad coupler. The coupler's trip pin is made from a curved metal rod made to suggest an air hose. When the trip pin passes over a magnet under the track (called an uncoupling ramp), the rod is pulled to one side, opening the knuckle and uncoupling the cars. See fig. 1.
Older models and inexpensive freight cars often have plastic horn-hook-style couplers, a design that's disappearing today. These have a plastic pin on the bottom of the coupler. When the pin passes through a grooved or spring ramp, the couplers are forced apart and the cars separate. Horn-hook and magnetic couplers are not compatible.
The caboose was the office for the conductor of a freight train and provided shelter for the train crew. A caboose typically offered a rough ride and little comfort to its crew. Those built through the early 1950s had smoky coal stoves used for heat in the winter. Because of the lack of comfort, crews often called cabooses "crummies." Though no longer a common sight, cabooses are still used occasionally where special switching work requires one
During the 1990s, the caboose was replaced with a small box called an end-of-train device (EOT or ETD). These mount on the coupler of the last car in a train and radio information to the locomotive cab about train-related data, such as brake-line air pressure. Some are equipped with a red flashing light
Full-length passenger car models (85 scale feet) can't go around tight curves on layouts. With that in mind, several model manufacturers developed lines of shorty passenger cars that, at 60 to 72 scale feet in length, can navigate the tight curves on smaller layouts.