The small ornate chimney located behind our present day toilets was originally linked to a boiler which fed a high pressure water system used to wash out the engines.
A washout was the process of removing sludge and scale from the insides of a steam engine boiler. The boiler was first emptied of steam and the hot water drained off. High pressure water was then hosed into the boiler through 'washout plugs' while rods were inserted into the plug holes to remove scale from the interior surfaces. After thorough cleaning, the boiler was visually inspected for defects. The need for washouts varied according to the age of the locomotive, the design of its boiler, its usage and the type of water used.
In order to allow all the parts of the boiler interior to be reached during a washout, washout plugs were provided in strategic positions. They were screwed into the boiler shell and were often numbered to ensure that they are replaced in the correct positions. Washout plugs were also useful for inspection purposes.
Steam engines took a lot of maintaining to keep them on top form. Unlike diesel, coal was dirty, cumbersome to handle and left a lot of residue. Mix the ash with steam and a sludge was produced which could build up very quickly. Much of the work at Barrow Hill was in routine maintenance to keep the engines operating efficiently.
Maybe this film can explain more of the processes needed to maintain a steam locomotive.
A smokebox is an important part of a steam locomotive's exhaust system. Smoke and hot gases pass from the firebox through tubes where they pass heat to the surrounding water in the boiler. The smoke then enters the smokebox, and is exhausted to the atmosphere through the funnel.
Ashes and soot which are naturally present in the smoke are deposited in the smoke box which sits at the front of the engine. The front of the smoke box has a door which is opened to remove these deposits at the end of each locomotive's working day. The handle must be tightened fully to prevent air leaks. Most British-built locomotives have a pair of smoke box door handles resembling the hands of a clock.
A spark arrester is often installed within the smoke box. This normally is a cylindrical mesh running from the top of the blast pipe to the bottom of the chimney. The purpose of a spark arrester is to prevent excessively large fragments of hot ash from being exhausted into the environment where they may pose a fire risk. Obviously to keep this effective and not restrict the air flow this also needed cleaning.