Steam Engine Tender - American Flyer
Steam Engine Tender – American Flyer

By the mid-1800s most steam locomotive tenders consisted of a fuel bunker (that held coal or wood) surrounded by a “U” shaped (when viewed from the top) water jacket. The overall shape of the tender was usually rectangular. The bunker which held the coal was sloped downwards toward the locomotive providing easier access to the coal.
The ratio of water to fuel capacities of tenders was normally based on two water-stops to each fuel stop because water was more readily available than fuel. One pound of coal could turn six pounds of water (0.7 gallons) to steam. Therefore, tender capacity ratios were normally close to 14 tons of coal per 10,000 gallons of water. One exception to this were the NYC tenders which were designed to pick up water at speed from track pans. These tenders had a much larger coal to water ratio.

Other factors which determined the size of tenders were turntable length. Some railroads bought large locomotives with small tenders so that they could still be turned on their existing turntables. In many cases, these tenders were replaced with larger ones as larger turntables became available. Construction styles also determined tender size. In 1927 the first solid steel cast tender frame made it possible to attach a single large tank called a “water bottom”. These tenders could hold 1,500 to 2,000 more gallons of water then previous tenders could.

There were a number of variations of tender design.