A tender or coal-car, is a special rail vehicle hauled by a steam locomotive containing the locomotive's fuel (wood, coal, or oil) and water. Steam locomotives consume large quantities of water compared to the quantity of fuel, so tenders are necessary to keep the locomotive running over long distances. A locomotive that pulls a tender is called a tender locomotive (or engine), which is commonly considered the standard steam locomotive.
Locomotives that do not have tenders and carry all their fuel and water on board the locomotive are called tank engines.
Locomotives that do not have a seperate tender and carry fuel supplies on articulated sectionsof themselves are called Garrats.
A brake tender is a heavy variant used primarily to provide greater braking efficiency.A Vanderbilt tender is a tender designed by Cornelius Vanderbilt. The tender is mainly meant for hauling or carrying oil or extra water. (The inventor actually named the unique tender after himself.)
Tenders have also been used on Gas-Electric Turbine diesel locomotives, such as the GE GTEL diesel locomotive.