Tender (rail)
A tender or coal-car (US only) is a special rail vehicle hauled by a steam locomotive containing its fuel (wood, coal, oil or torrefied biomass) and water.
In the UK and parts of Europe, a plentiful supply of coal made this the obvious choice from the earliest days of the steam engine.
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.
Refilling the tender is the job of the fireman, who is responsible for maintaining the locomotive's fire, steam pressure, and supply of fuel and water.
The Southern's decision to electrify its routes into London with a third rail system also made the installation of water troughs impractical.
Only on the former London and South Western Railway routes west of Salisbury, where long-distance express trains operated, was the lack of troughs a problem.
Rather than install troughs the L&SWR (and the Southern) equipped its express locomotives with special high-capacity tenders with a water capacity of 4,000 gallons (18,200 L) running on a pair of twin-axle bogies.
[2] A primitive approach to condensation simply injected the spent steam into the tender tank, relying on the mass of water for cooling.
[2] More sophisticated tenders, such as those used in the South African Railways Class 25 locomotives designed for service in the Karoo, replaced most of the water tank with a huge radiator, in which the steam was cooled and condensed.
Exhaust steam, after passing through an oil-water separator, was conveyed to the tender, where it powered a low-pressure turbine used to drive the radiator fans.
[3] Eventually the SAR examples were converted to conventional locomotives by replacing the radiator with a long water tank.
Much of the fireman's time is spent throwing wood or shoveling coal into the firebox of the locomotive to maintain constant steam pressure.
[5] Consequently, in the United States, various steam-powered mechanical stokers (typically using an auger feed between the fuel bunker and the firebox) became standard equipment and were adopted elsewhere, including Australia and South Africa.
In the early days of railroading, tenders were rectangular boxes, with a bunker for coal or wood surrounded by a U-shaped water jacket.
[6] Vanderbilt was the great-grandson of the founder of the New York Central Railroad; his tender featured a cylindrical body like a tank car with a fuel bunker set into the front end.
[9][10] For the introduction of the London and North Eastern Railway's non-stop Flying Scotsman service on 1 May 1928, ten special tenders were built with means to reach the locomotive from the train through a narrow passageway inside the tender tank plus a flexible bellows connection linking it with the leading coach.
[11][12] Use of the corridor tender for changing crews on the move in an A4 loco is shown in the 1953 British Transport film Elizabethan Express, the name of another London-Edinburgh non-stop train.
In New South Wales these vehicles were called "gins", and were used in the predominantly dry western region and on some branch lines.
Some of the tenders survived the Burlington Northern Santa Fe merger but retain the black and green BN colors.
Tenders have also been developed to carry liquefied natural gas for diesel locomotives converted to run on that fuel.
[14] On British railways, brake tenders were low, heavy wagons used with early main line diesel locomotives.
[18] The body was filled with scrap steel to raise the weight of the vehicle to 35+1⁄2–37+1⁄2 tons; consequently increasing the available brake force.
None survived in preservation but an operational replica has been constructed on the Great Central Railway from the remnants of a Mk1 corridor coach and has been given the next number in the brake tender sequence; B964122.
Powered tenders were used extensively on geared logging steam locomotives like the Shay, Climax, and Heisler types where the steep grades and heavy trains necessitated the extra tractive effort.
The numerous DRB Class 50 (2-10-0) locomotives, for example, were capable of 80 kilometres per hour (50 mph) in either direction, and were commonly used on branch lines without turning facilities.
In some instances, particularly on branch lines having no turnaround such as a turntable or wye at the terminus point, locomotives ran in reverse with the tender leading the train.
