page_title: Track pan
section_title: Origin
hierarchical_section_title: Track pan / Origin
caption_attribution_description: Water troughs on the LNWR railway designed by Ramsbottom
context_page_description: A track pan or water trough is a device to enable a steam locomotive to replenish its water supply while in motion. It consists of a long trough filled with water, lying between the rails. When a steam locomotive passes over the trough, a water scoop can be lowered, and the speed of forward motion forces water into the scoop, up the scoop pipe and into the tanks or locomotive tender.
context_section_description: Steam locomotives consume a considerable amount of water, and the tender or side tanks need to be replenished at intervals. Traditionally the engine water was replenished during station stops, but if it was desired to run long distances without stopping, the requirement to take water was a significant limitation. The Railway Magazine reported a development by John Ramsbottom:
  In the year 1860 the London and North-Western Company having decided to accelerate the Irish mail [express train], Mr. Ramsbottom, then their chief mechanical engineer, was asked to make the run between Chester and Holyhead, ​84 ³⁄₄ miles, in 2 hours 5 minutes... It was clear that if the usual stop on the road to take in water could be avoided, an important point would be gained; but there were no tenders of sufficient capacity to hold the quantity of water required to enable an engine to run through without stopping. In an ordinary way, from 1,800 to 1,900 gallons were consumed, but in the rough and stormy weather frequently experienced along the exposed coast of North Wales it was not unusual for the consumption to rise to 2,400 gallons; whilst the largest tenders only held 2,000 gallons.
  Ramsbottom arranged some experiments and showed that the forward motion of a scoop in a trough of water would force water up a connected pipe and into a tank. He calculated the quasi-static head produced by the forward motion:
  …at a velocity of 15 miles an hour the water is lifted ​7 ¹⁄₂ ft., this was exactly the result attained in practice by the apparatus; at this speed the water was raised to the top of the delivery pipe (​7 ¹⁄₂ ft.), and was there maintained without running over into the tender whilst the scoop was in action. Again, theoretically the maximum amount of water the pipe was capable of raising was 1,148 gallons—5 tons—and this was reached when the engine was moving at the rate of about 80 miles an hour. The result of experiments made at different speeds was that at 22 miles an hour the delivery was 1,060 gallons; 33, 1,080; 41, 1,150; and 50, 1,070; showing that the quantity delivered varies very little at speeds above 22 miles an hour, which is accounted for by the shorter times the scoop is passing through the water.
  The track is raised a little over a short distance each end of the trough, so that the engine, and the scoop which may already be lowered, descend into the trough:
  Many people think the scoop is let down into the water whilst the engine is passing over the trough, and has to be withdrawn immediately it readies the further end; but this method would not work, the time is too short. The scoop may be lowered at any distance before it arrives at the trough, and will run clear of everything until, by a very simple and ingenious arrangement, it dips automatically into the water to the required depth of 2 in. The rails at each side of the trough are laid on a level slightly lower than the surface of the water, and as the engine descends to this level, the scoop, which is so adjusted that the lower edge is the same height as the rails, descends with it and becomes immersed in the water. To save lowering the line the whole distance, a short incline is made, rising to a height of about 6 in. at a point 16 yards from the commencement of the trough; the line then falls to the level it maintains until it reaches the further extremity of the trough, when there is again a slight rise which carries the scoop out of the water and clear of the end of the trough.
  The first installation was brought into use on 23 June 1860 at Mochdre, Conwy, on the London & North Western Railway's (LNWR) North Wales Coast Line, midway between Chester and Holyhead.
  The siting of the troughs requires a long enough length of straight and level track (although very large radius curves could be accommodated). For instance, the LNWR placed water troughs within the Standedge Tunnels, as they were the only sufficiently straight and level portion of the line between Huddlesfield and Manchester. There must be a good water supply nearby. In hard water areas, water softening plant
caption: Ramsbottom water troughs on a four-line stretch of the West Coast Main Line, England in 1904.
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