Short hood

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The short hood of a hood unit-style diesel locomotive is, as the name implies, the shorter of the two hoods (narrower sections of the locomotive body in front and behind of the cab) on a locomotive. The short hood contains ancillary equipment, frequently a chemical-retention toilet for crew use, and may contain a steam generator for heating older-style passenger cars.

Normally, the short hood is the front of the locomotive, and may be referred to as the locomotive's "nose". Originally, this was not the case; railroads preferred to have the long hood leading, for additional crew protection in a collision. The requirement for increased visibility conflicted with this and ultimately gained precedence. Many locomotives originally had a short hood the full height of the locomotive (a high short hood). This gave extra equipment room and was often used to house a steam generator. Once the short hood was established as the front of the locomotive, manufacturers began to offer a low short hood, which was below the level of the locomotive's cab windows and allowed for center windows for better forward visibility. Many older locomotives were modified to have a low short hood and were referred to as chop-nosed.

More recently, it has become the standard for the locomotive's nose to be built full-width, instead of having a narrow short hood. This is officially known as a "safety cab" (sometimes "Canadian safety cab" since Canadian railroads were the first to specify these) and is often, but inaccurately, described as "wide cab" by railfans (the cab is no wider; it is the nose or short hood that is wider).