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Steam engines used emormous amounts of water but, as we know from domestic kettles and irons, water can be either hard or soft and can contain many impurities.
There was a great potential for a build up of limescale and the production of sediment which generally affected performance and was difficult to remove.
The problem faced by railway operators was that most freely available water contained traces of organic matter and much of the water taken from boreholes was, and still is, laced with calcium and magnesium salts. This ‘hard’ water was a significant problem in a locomotive boiler as these soluble salts became solids as the temperature and pressure increased. As these salts touched the hot surfaces some baked and formed a scale, others sank and formed a sludge on the bottom of the boiler. Both caused significant problems in hampering the efficiency of the boiler by both decreasing heat conductivity and impeding the water flow.
Even apparently clean water skimmed from rivers and lakes could be a problem as the absorbed carbon dioxide released pure oxygen during heating which is an essential requirement of corrosion.
Railway companies had several methods to deal with this problem. Simple filtration was able to remove most organic matter, both of animal and vegetable origin. Dealing with ‘hard’ water was a different matter. Where there was a great need for water in locations such as locomotive maintenance and stabling sheds, large stations and major siding and shunting complexes, there would be specialized water softening plants. These plants added chemicals to the water including hydrated lime, sodium carbonate or sodium aluminates. Where such plants were not available the problem was solved by adding water softening blocks directly into locomotive tenders, pannier or saddle tanks.
Filling the locomotives was achieved by the use of water cranes, columns or a parachute tanks, normally gravity fed from a supply tank. At Barrow Hill, two water cranes may be viewed. One at the bottom of the platform and one from the coaling stage viewing area. These are both fed from the tank seen above our joiners shop.
A major task at Barrow Hill was washing out the boilers of steam locomotives to remove sludge and deposit build up. The chimney beside the mess room at Barrow Hill is the only remnant of the boiler system which created the pressurized water used for this task. Depending on the age and state of the locomotives and the water they used this work might be carried out three or four times a month. This might represent as few as 500 or as many as 6000 miles.
On long journeys the quantity of water able to be carried by the locomotive was often insufficient to complete the journey or there might be an inadequate supply at the destination. Designers came up with a novel way of replenishing water on the move by the use of troughs between the rails and water scoops in the tenders. The scoop, when lowered, could scoop up about 2000 gallons from these troughs which were about 600 yards long. From the film below it might be seen that this was a labour intensive job, winding down the scoop and rewinding before the end of the trough was reached. The optimum train speed for this operation was between 45 to 60 mph. The lower speeds achieved by the Barrow Hill freight engines meant that this system was rarely used by our locomotives. The only trough the engines worked over was between Burton-on-trent and Tamworth.
On none stop runs like the ‘Elizabethan’, Kings Cross to Edinburgh, a journey of nearly 400 miles, six troughs were used to keep the 5000 gallon tender on the A4 Locomotives topped up. Another point to consider on some long haul runs was that often the tender contained a passageway, front to back, to allow for crews to change over without stopping which reduced tha available space for water.
In some cases a double tender arrangement was utilised to solve this problem.
Interestingly the Class 40 diesel also had a scoop pickup system to collect water to steam heat the carriages.
With a Class 8F Locomotive and a full train of wagons, the locomotive would use about ¾ of the 4000 gallon tank on the trip from Barrow Hill to Toton. The locomotive tank would be filled up at Toton Shed where the locomotive was turned. The filling operation was often done before turning to help with the balance of the Locomotive on the turntable. This problem was sometimes seen at Barrow Hill where an empty tender made our turntable difficult to turn, the light tender putting all of the weight of the locomotive on the front end.
In the winter during severe frost the leather bag or hose on the water cranes would freeze and frost fires were lit around the base. One of these has been made as an example and can be seen on the water crane by the coaling stage viewing area.
M Creagh, observations from Barrow Hill by Dave Darwin, photographs from Barrow Hill Archive collection
Diagram of a Steam Locomotive tender showing the approximate space used by the coal (grey) and water (blue). The lowerable water scoop is also shown.
Ratio of coal to water is about 7 tones of coal to 5000 gallons of water. 1 pound of coal can turn 0.7 gallons of water to steam.
Steam locomotives generally needed to carry both combustable fuel and water. The weight of this fuel was quite considerable, a typical tender locomotive carrying 7 tons of coal and 5000 gallons of water which weighed about 20 tons (8.34 pounds per gallon). The exception to this is where the locomotive is provided with a pressurised tank of steam from an external source, normally used in industrial locations.
The design of the locomotive varied considerably according to how this fuel was carried and we have several examples at Barrow Hill.
Tank engines were the backbone of most shunting yards, industrial locations and short mainline journeys. Small engines that were capable of running equally fast in both directions, they usually had symmetrical wheel arrangements to ensure the same ride and stability characteristics regardless of the direction travelled, producing arrangements with only driving wheels (0-4-0T and 0-6-0T) or equal numbers of leading and trailing wheels (2-4-2T, 4-6-4T etc.). However other requirements, such as the need to support a large bunker, would require a non-symmetrical layout such as 2-6-4T.
There are a number of types of tank engine, based on the location and style of the water tanks. These include the side tank, the saddle tank, the pannier tank, the well tank and others. While a tender engine might be described as an 0-6-0, the matching tank engine would be described as an 0-6-0T for a plain tank, an 0-6-0ST for a saddle tank, 'PT' indicating a pannier tank, 'WT' a well tank, etc.
The water is contained in rectangular tanks which are mounted on either side of the locomotive, mounted close to the boiler but not quite touching. The tank sides extend down to the running platform for at least part of their length.
The length of the side tanks was designed to give access to the inside motion. Sometimes apertures were provided to allow access to important maintenance points. With larger side tanks the front end might be tapered the tanks slightly at the front end to improve forward visibility. Side tanks usually stopped before the end of the boiler barrel, with the smokebox protruding ahead. The designs which extended to the front of the smokebox were called 'flatirons'.
The water tank sits on top of the boiler as a saddle might sit on a horse. There were various shapes utilized in this design. The tank could be curved in cross-section, they could be curved with straight sides (like an inverted 'U'), or even an ogee shape. Many smaller industrial locomotives were made to this design. However it had a few problems in spite of the quantity of water it could hold, the size of the boiler was controlled and the design restricted access for cleaning. Because of the higher centre of gravity the engine became unstable on bends and had to run at lower speeds, not really a problem when shunting. The sheer bulk of the tank also restricted the view of the driver.
Panier tanks were rarely seen around this area as they were in use mainly by the Great Western Railway. These had long tanks carried alongside the boiler which did not go over the top of the engine and not reach down to the main frame of the locomotive thus lowering the centre of gravity and giving easy access to the running mechanisms.
Rarely found in mainline locomotives because the tank, suspended below the locomotive, was restricted in size which limited the effective range. The low centre of gravity gave much better stability on poorly laid or smaller gauge tracks. However, some engines had a combination of side mounted and well tanks to extend their range.
Long journeys needed big, powerful engines which demanded lots of fuel and of course water. Having a separate tender gave the necessary reserves of fuel but gave a few disadvantages too. The speed of the engine was signficantly reduced in reverse and the view of the driver also limited by the bulk of the tender.
This photograph shows a 0-4-4 well-tank (double frame) No. 1211, built by Beyer-Peacock & Co. in 1869
We have several fine examples of tender engines at Barrow Hill, all on loan from the National Railway Museum. The J17 workhorse is typical of the type of engine used for freight at Barrow Hill, whilst the stunning Midland Compound 1000 represents a triumph in engineering. This and the The Butler Henderson Director Class locomotive feature the water scoop which may be glimpsed under the tenders.
Maybe the best explanation about water scoops is done by Pike from Dads Army.
Extract from 'The Royal Train' S06 E03
The water scoops can be seen under the tenders of The Butler Henderson and The Midland Compound 1000 locomotives.
Extract from the film 'Elizabethan Express' located on YouTube
The extract shows the change-over of locomotive crew common on long journeys, the access to the cab through the tender and the process of getting water from a trough.
The 'Peckett' standing beside one of our two water cranes
Our water tank can be seen at the far end behind the small chimney.