A water crane is a device used for delivering a large volume of water into the tank or tender of a steam locomotive.[1] [2] [3] The device is also called a water column in the United States and Australia.[4] As a steam locomotive consumes large quantities of water, water cranes were a vital part of railway station equipment, often situated at the end of a platform, so that water could be refilled during a stop at the station.
Generally, water cranes consist of an upright steel pipe about 8inchesto12inchesin (toin) in diameter with a horizontal, pivoting pipe connected to its upper end so as to form a swinging arm. The swinging arm is usually designed to rest parallel to the rails when not in use.[5] Water cranes may be able to deliver up to 10abbr=noneNaNabbr=none of water per minute.
In hilly country, natural streams can be dammed and water fed by gravity to the water crane.[6] In flatter country this arrangement is not always possible, so water may be supplied by a tank next to the crane. Water tanks may vary in volume from 190m2 to greater than 757m2. In some cases a well may be used to supply the water to the tank.[7]
Depending on the quality of the water under supply, it may need to be treated chemically to eliminate hardness which induces scale buildup on the inside of the locomotive boiler.[8] The scale which builds up on heat transfer surfaces forms a layer of insulation between the metal of the firebox and the boiler water.[9] This causes metal to overheat or corrode and eventually fail.