Tender (rail)

"Coal car" redirects here. For the modified automobile once popular in Vietnam, seeXe than.For freight cars that carry coal, seeHopper car,Gondola (rail),andOpen wagon.

Sierra Railway No. 3tender

A BritishSECR O1 classruns tender-first at theBluebell Railway

Cutawaycross section showing a Spanish tender designed for fuel oil. Green areas hold water and brown areas hold fuel oil. There is a special arrangement to prevent sloshing around during the movement of the train.

Atenderorcoal-car(US only) is a specialrail vehiclehauled by asteam locomotivecontaining itsfuel(wood,coal,oilortorrefiedbiomass) and water. Steam locomotives consume large quantities of water compared to the quantity of fuel, so their tenders are necessary to keep them running over long distances. A locomotive that pulls a tender is called atender locomotive.Locomotives that do not have tenders and carry all their fuel and water on board the locomotive itself are calledtank locomotivesor tank engines.

Acorridor tenderis a locomotive tender with a passageway to one side, allowing crew changes on the fly.

Abrake tenderis a tender that is heavy and used (primarily) to provide greater braking efficiency.

General functions

The largest steam locomotives are semi-permanently coupled by adrawbarto a tender that carries the water and fuel. The fuel source used depends on what is economically available locally. In theUKand parts ofEurope,a plentiful supply ofcoalmade this the obvious choice from the earliest days of the steam engine. Until around 1850 in theUnited States,the vast majority of locomotives burned wood until most of the eastern forests were cleared. Subsequently, coal burning became more widespread, and wood burners were restricted to rural and logging districts.

Water supply

SNCF 241P Classwith 34P bogie tender, being filled from a water crane (Nantes Blotterau, France, August 1969)

Shay locomotiveDixianaat theRoaring Camp and Big Trees Narrow Gauge Railroad,Felton, California,with woodenwater towerand extendablespigotvisible in the background

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 [0.45 kg] of coal could turn six pounds of water (0.7 gallons) [2.7 kg] to steam. Therefore, tender capacity ratios were normally close to 7 tons (14,000 lb) [6,400 kg] of coal per 10,000 gallons [38,000 L] of water.

The water supply in a tender was replenished at water stops and locomotive depots from a dedicatedwater towerconnected towater cranesor gantries. Refilling the tender is the job of thefireman,who is responsible for maintaining the locomotive's fire, steam pressure, and supply of fuel and water.

Water carried in the tender must be forced into theboiler,to replace that which is consumed during operation. Early engines used pumps driven by the motion of the pistons. Later,steam injectorsreplaced the pump while some engines usedturbopumps.

With track pans or water troughs

In the UK, the US and France,water troughs(in the US, track pans) were provided on some main lines to allow locomotives to replenish their water supply while moving. A "water scoop" was fitted under the tender or the rear water tank in the case of a large tank engine; the fireman remotely lowered the scoop into the trough, the speed of the engine forced the water up into the tank, and the scoop was raised once it was full.

The fuel and water capacities of a tender are usually proportional to the rate at which they are consumed, though there were exceptions. ThePennsylvania Railroadand theNew York Central Railroadusedtrack panson many of their routes, allowing locomotives to pick up water at speed. The result was that the water tanks on these tenders were proportionally much smaller.

In theUKwater troughs were used by three of theBig Fourrailways. The exception was theSouthern Railway– mainly because the majority of the Southern's operations were based around short-distance commuter, suburban and rural services with frequent station stops where water could be taken on fromwater columns.The Southern's decision toelectrifyits routes intoLondonwith athird railsystem also made the installation of water troughs impractical. Only on the formerLondon and South Western Railwayroutes west ofSalisbury,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-axlebogies.These were known to railwaymen as "water cart" tenders.

Condensing tenders

Tender from anSAR Class 25condensing locomotive; note the large radiator section

Condensing steam locomotiveswere designed to recycle exhaust steam by condensing it into feed water. The principal benefit is conservation of water, but thethermal efficiencyof the engine is also increased, since much of the heat otherwise lost in the exhaust is used to preheat water injected into the boiler.In some cases condensing was employed simply to improve visibility by eliminating clouds of exhaust.

A primitive approach to condensation simply injected the spent steam into the tender tank, relying on the mass of water for cooling.More sophisticated tenders, such as those used in theSouth African RailwaysClass 25locomotives designed for service in theKaroo,replaced most of the water tank with a huge radiator, in which the steam was cooled and condensed. Exhaust steam, after passing through anoil-water separator,was conveyed to the tender, where it powered a low-pressure turbine used to drive the radiator fans. The steam then passed into the radiator. The condensate was injected into the boiler with another turbine-driven pump.This was a quite complex bit of machinery, also requiring another turbine in the smokebox to provide the exhaust draft normally obtained by blowing the exhaust steam up the stack.Eventually the SAR examples were converted to conventional locomotives by replacing the radiator with a long water tank.

Fuel supply

A factor that limits locomotive performance is the rate at which fuel is fed into the fire. Much of the fireman's time is spent throwing wood or shoveling coal into the firebox of the locomotive to maintain constant steam pressure. In the early 20th century some locomotives became so large that the fireman could not shovel coal fast enough.Consequently, in the United States, various steam-poweredmechanical 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.

Tender design variants

A locomotive and tender designed byClaude Verpilleuxaround 1842 for theSaint-ÉtiennetoLyonrailway in France

In the early days of railroading, tenders were rectangular boxes, with a bunker for coal or wood surrounded by a U-shaped water jacket. This form was retained up to the end of steam on many coal-burning engines. Oil-burning engines substituted a fuel tank for the bunker. Variations on this plan were made for operational reasons, in attempts to economize on structure.

Vanderbilt

Cylindrical Vanderbilt tender, of the Canadian National

In early 1901,Cornelius Vanderbilt IIIfiled a patent application covering a new type of tender. Vanderbilt was the great-grandson of the founder of theNew York Central Railroad;his tender featured a cylindrical body like atank carwith a fuel bunker set into the front end. This design was soon adopted by a number ofAmerican railroadswith oil-burning and coal-burning locomotives.

Compared to rectangular tenders, cylindrical Vanderbilt tenders were stronger, lighter, and held more fuel in relation to surface area. Railroads who were noted for using Vanderbilt tenders include:

• Baltimore & Ohio
• Canadian National
• Grand Trunk Western
• Great Northern Railway
• Southern Pacific
• Union Pacific
• New Zealand Railways Department(NZR AB class,NZR J class,NZR G class (1928)).
• Nashville, Chattanooga and St. Louis Railway
• Seaboard Air Line Railroad
• South African Railways

Whaleback

Whaleback tender built for theKahului Railroadin 1928

A form peculiar to oil-burning engines was the "whaleback" tender (also sometimes called a "turtle-back" or "loaf" tender). This was a roughly half-cylindrical form with the rounded side up; the forward portion of the tank held the oil, while the remainder held the water. This form was particularly associated with theSouthern Pacific.

Slopeback

Locomotive with slopeback tender, loading theSunset Limitedonto the train-ferrySolanoatPort Costa,San Francisco,Southern Pacific R.R.

In the United States, tenders with sloped backs were often used for locomotives in yardswitchingservice, because they greatly improved the engineer's ability to see behind the locomotive when switching cars. The reduced water capacity was not a problem, as the tender's water tank could be frequently refilled in therail yard.In the 1880s, numerous locomotive manufacturers were offering tenders with this design on smallswitcher locomotives.

Corridor

Main article:Corridor tender

LNER Class A1No. 4472Flying Scotsmanwith corridor tender

For the introduction of theLondon and North Eastern Railway's non-stopFlying Scotsmanservice 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 bellowsconnectionlinking it with the leading coach. The passageway, which ran along the right-hand side of the tender, was 5 feet (1.52 m) high and 18 inches (0.46 m) wide. Further corridor tenders were built at intervals until 1938, and eventually there were 22; at various times, they were coupled to engines of classesA1, A3,A4andW1,but by the end of 1948, all were running with class A4 locomotives.Use of the corridor tender for changing crews on the move in an A4 loco is shown in the 1953 British Transport filmElizabethan Express,the name of another London-Edinburgh non-stop train.

Water cart

ASouthern Railway (Great Britain)locomotive with a "water cart" tender

Thewater cartwas a type of high-capacity tender used by theLondon and South Western Railwayin England. Unlike the usual British six-wheel tender, it was a double-bogie design with inside bearings. This gave it a distinctive appearance because the wheels were very obvious.

Canteen

"Bittern"with second tender at York

An additional tender which holds only water is called a "canteen" or "auxiliary tender". During the steam era, these were not frequently used.Water tankswere placed at regular intervals along the track, making a canteen unnecessary in most cases. However, there were times that canteens proved economical. TheNorfolk and Western Railwayused canteens with its giant2-8-8-2Y Class and2-6-6-4A Classlocomotives on coal trains, timed freights, fast freights, and merchandise freights. Use of the canteen allowed one of thewater stopsto be skipped, allowing the train to avoid climbing a hill from a dead stop. Currently, theUnion Pacific Railroaduses two canteens with its steam locomotives844and4014on excursion trains. Virtually all the trackside tanks were removed when steam locomotives were retired. Nowadays,fire hydranthookups are used, which fills the tanks much more slowly. The canteens allow for greater range between stops.

Canteens were also used on theTrans-Australian Railwaywhich crosses the waterlessNullarbor Plain.In New South Wales these vehicles were called "gins", and were used in the predominantly dry western region and on some branch lines. Now prominently use on heritage excursions due to the lack of places with accessible water points. During the catastrophic 2019-2020 bushfire season, as fires devastated towns near the Rail Transport Museum at Thirlmere, south of Sydney, a diesel locomotive from the museum hauled two gins to help replenish firefighting tanker trucks.

In the United Kingdom, a canteen was used on the preservedFlying Scotsmanduring enthusiast excursions in the late 1960s and early 1970s. Thewater troughsthat had previously supplied long-distance expresses had been removed duringdieselisationof the railway network. On 25 July 2009,Bitternmade a 188-mile run from King's Cross to York non-stop using a second tender. As railways in Britain tend to be much shorter than those in the US, the canteen was not an economical proposition.

Fuel tender

SCT Logisticstrain with tank car supplying fuel to the locomotives, reducing the number of fuel stops required on the transcontinental journey across Australia

Sometimes a tender will be used for adiesel locomotive.This is typically a tank car with a fuel line that connects to the locomotive andMUconnections to allow locomotives behind the tender to be controlled remotely. TheBurlington Northern Railroadused fuel tenders in remote territory where fuel was expensive. Diesel fuel could be bought cheaply and loaded into the tender. A common consist was twoEMD SD40-2swith a tender between them. Some of the tenders survived theBurlington Northern Santa Femerger but retain the black and green BN colors. TheSouthern Pacific Railroadalso briefly experimented with fuel tenders for diesels. Someslugshave fuel tanks and serve as fuel tenders for the attached locomotives, especially those that are converted from locomotives that are retired due to worn-out diesels.

TheUnion Pacific Railroadused fuel tenders on itsturbines.These tenders were originally used with steam locomotives, then reworked to hold heavy "Bunker C" fuel oil. Fuel capacity was about 23,000 gallons (87,000 liters). When the turbines were retired, some of the tenders were reworked to hold water, and employed as canteens for steam locomotives.

Fuel tenders have also been the cause of controversy for railroads, in particularthe Soo Line. In the late 1970s, the management of the railroad discovered that it was cheaper for them to fill their fuel tenders at Chicago, and then transport the fuel to Shoreham Wisconsin. Doing this avoided the railroad needing to pay extra taxes on the fuel, and the system was continued until the mid 1980s. When the states ofIllinoisandWisconsincaught onto the railroad's actions, legislation was passed which charged the same over the road tax on the fuel movement over rail which was charged for truck drivers. Doing this completely negated the benefit of moving the fuel by way of the tenders, and Soo quietly withdrew the practice.

Tenders have also been developed to carryliquefied natural gasfor diesel locomotives converted to run on that fuel.

Brake tender

OnBritish railways,brake tenders were low, heavy wagons used with early main linediesel locomotives.One or two were coupled in front or behind the locomotive to provide extra braking power when hauling unfitted or partially fitted freight trains (trains formed from wagons not fitted with automatic brakes).They were required as the lighter weight of the new diesel locomotives, compared to steam, meant that they had comparable tractive effort (and thus train hauling capacity) but less braking ability.Originally intended to be used in North East England, where they were usually propelled (pushed) by the locomotive, and later used in other regions. On theSouthern Regionthey were normally hauled behind the locomotive.

The tender took the form of a hollow box, low enough to avoid obscuring the driver's view when pushed. The body was carried on a pair of former carriage bogies, which provided the automatic brakes.The body was filled with scrap steel to raise the weight of the vehicle to35+1⁄2–37+1⁄2tons; consequently increasing the available brake force.Four lamp brackets were provided at each end to display locomotive headcode discs describing the class of train – when propelled, the tender obscured the front of the locomotive, and hence the headcode.

Introduced around 1964–65, they were taken out of use in the 1980s when the practice of using unfitted trains was discontinued. None survived in preservation but an operational replica has been constructed on theGreat Central Railwayfrom the remnants of a Mk1 corridor coach and has been given the next number in the brake tender sequence; B964122.

Powered tender

Certain early British steam locomotives were fitted with powered tenders. As well as holding coal and water, these had wheels powered from the locomotive to provide greater tractive effort. These were abandoned for economic reasons; railwaymen working on locomotives so equipped demanded extra pay as they were effectively running two locomotives. However, the concept was tried again on theRavenglass and Eskdale Railway'sRiver Mite,and theGarratt locomotivemay be seen as an extension of this principle. Powered tenders were also seen on thetriplex locomotivesin the United States, but these experiments were not considered successful due to the varying mass of the tender. Powered tenders were used extensively on geared logging steam locomotives like theShay,Climax,andHeislertypes where the steep grades and heavy trains necessitated the extra tractive effort.

Nowadays, slugs are used withdiesel-electric locomotives.The slug hastraction motorsthat draw electricity from the locomotive'sprime moverto provide extratraction.

German practice

In Germany, attention was given to ensuring that tender locomotives were capable of moderately high speeds in reverse, pushing their tenders. The numerousDRB Class 50(2-10-0) locomotives, for example, were capable of 80 kilometres per hour (50 mph) in either direction, and were commonly used onbranch lineswithout turning facilities.

A source of possible confusion with regards to German locomotives is that inGerman,Tenderlokomotivemeans a tank locomotive. A locomotive with a separate, hauled tender is aSchlepptenderlokomotive.

Tender-first operations

PreservedLMS Ivatt Class 2 2-6-0no. 46443 atBewdleyon theSevern Valley Railway.The front of the tender has a half-cab for tender-first running.

In some instances, particularly on branch lines having no turnaround such as aturntableorwyeat the terminus point, locomotives ran in reverse with the tender leading the train. In such instances, a headlamp (US) or headcode lamps/discs were placed on the leading end of the tender. Locomotive crews often rigged atarpaulin(or the locomotive's storm sheet, if available) from the rear of the cab roof to the front of the tender to provide protection from the wind and to prevent coal dust being blown into the cab. Tenders designed for more frequent tender-first workings were often fitted with a fixed cab panel and windows, providing an almost fully enclosed cab.

See also

• Coal bunker

Further reading

• Lustig, David (2023-10-16)."Steam locomotive tenders have a life of their own".Trains.Retrieved2023-10-17.

External links

• United States locomotive tenders