Water trough

Again, theoretically the maximum amount of water the pipe was capable of raising was 1,148 gallons [5,220 L]—5 tons—and this was reached when the engine was moving at the rate of about 80 miles an hour [130 km/h].

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 [5 cm].

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 Huddersfield and Manchester.

The scoop was purposely made of light construction so that, should it strike an obstruction, it tore away, causing no serious damage to the locomotive or its trailing vehicles.

Failure to raise the scoop promptly when the tanks are full would resulted in large volumes of water being expelled from the vents, soaking the tender and footplate.

The fireman therefore had to observe the water level indicator (a float in the tank, connected to an external pointer) carefully and be poised to retract the scoop as necessary.

Lineside indicators were provided to assist engine crews in determining the location; in the UK it was a large white rectangular board with a black horizontal zigzag marking.

On American railroads, illuminated trackside signals were employed for night-time usage, to indicate the start and approaching end of the track pan.

At that speed 944 imp gal (4,290 L) could be picked up in 440 yards (400 m), but Vaughan suggests that this is a low theoretical figure, and that it overlooks the bow wave effect which enables a greater take-up rate.

There was a significant resistance to the forward motion of the engine during the process, enough to require special care by the driver to avoid problems on unfitted freight trains.

[2] The considerable water spray made track maintenance difficult, and the physical trough equipment limited access for packing sleepers, exacerbating the problem.

If the tender were done away with, the coals, and a small tank with a capacity of forty or fifty gallons [180 or 230 L] to receive the water, and from which to supply the boiler, would have to be carried on the engine.

[1]Railway companies were well aware of the cost of installing and maintaining this equipment, and the provision of tenders with a large water capacity was an alternative employed in some cases.