AY Honors/Model Railroad/Answer Key

A modern tank car in a westbound UP train at Rochelle Railroad Park, Rochelle, Illinois, on May 29, 2005.

A tank car on display at the Mid Continent Railroad Museum in North Freedom, WI.

A tank car is a piece of railroad rolling stock designed to carry liquified loads. Many variants exist due to the wide variety of liquids that can be transported. Tank cars can be insulated or non-insulated, pressurized or non-pressurized, and designed for single or multiple loads. Non-pressurized cars have a prominent dome at the top to allow for thermal expansion of the contents, and plumbing at the bottom for unloading. Pressurized cars have a sealed manhole at the top. Loading and unloading are done through this opening. Insulated cars are used when the contents must be kept at a certain temperature. Cars designed for multiple loads have internal bulkheads to separate the contents. Non-pressurized multiple load cars are easy to spot as each compartment has an expansion dome.

Some truly gigantic tank cars have been built, riding on as many as eight axles. No more of these "rail whales" will be built, however. New regulations prohibit new ones from being built, and existing giants must eventually be retired.