Locomotive Firing Methods

In the course of a lecture recently delivered by Mr. James T. Hodgson at a meeting of the Railway Locomotive Men's Craft Guild at the College of Technology, Manchester (says the Railway Gazette, 12/2/26), reference was made to the automatic manner in which the locomotive draught is varied according to the load on the engine. The author further stated that the fuel on the fire-bed could also be regarded as a draught regulator, in that the rate at which the air passes from the ash-pan through the bed of fuel can be determined to a certain extent by the size of the coal and the thickness of fire-bed carried. In other words, the thin portion of the fire-bed offers less resistance than the thicker portion; hence, if the fire be carried too thin against the fire-box plates, this portion of the fuel provides the path of least resistance, and an excess of air passes through these portions of the fire grates. The best methods of firing were accordingly said to be those which prevent recurring damping effects, as when coal is fired in too large quantities, or chilling effects, as when air is allowed to pass in excessive quantities through the thinner portions of the fire-bed. The endeavours of the firemen, should, therefore, be concentrated in an effort to maintain a uniform depth of fire-bed, which should be slightly thicker against the fire-box plate and to maintain the highest fire-box temperature obtainable irrespective of the demands for steam. Considerable skill is required in firing a locomotive, especially when working under difficult conditions, the object aimed at being to obtain the maximum number of heat units as the demand for steam increases, and to maintain a high fire-box temperature without blowing off at the safety valves.