The Locomotive Of Today

The Boiler : Water Gauge Columns. 45 Water gauge columns are provided at the back of the outer firebox to enable the level of the water in the boiler to be readily discerned. They consist of suitable brass mount- ings, the upper one communicating with the steam space, and the *lower with the water, a glass tube connecting the two, and occupying the range within which the water level must be kept. The best level for all practical purposes is about two-thirds of the distance up the glass when the regulator is open; carrying the water higher than this increases the tendency to prime, especially when the water is not clean. Should the water disappear below the bottom of the glass it may be assumed the crown plate of the firebox is dangerously near over-heating, and it would be advisable, if the level of the water cannot be raised, to at once draw the fire or smother it with sods of earth or ballast thrown on it, and shut the damper. At A, Fig. g, is shown an ordinary pattern of column, consisting of an upper cock fixed to a flange studded on to the boiler, and a lower one similar to it, with a third cock at the bottom for allowing the glass to be cleaned by biowing steam through it. A drain pipe is attached to this last, and is carried down to the ashpan. The top and bottom fittings are provided with giands and stuffing boxes, through which the glass, which is from ^-in. to f-in. diameter, passes. The cocks are ordinary ground-in plug cocks connected together by a rod, so that when a glass breaks the two can be simultaneously closed. Both fittings have small plugs immediately opposite the holes in the firebox fronts, through which a wire can be passed for cleansing purposes. As there is considerable danger of being scalded by the water when a glass breaks, several methods have been devised to automatically close the water and steam ways when such a mishap occurs. At B is given a form which has been intro- duced by Messrs. Dewrance, of 158, Great Dover Street, London, S.E., and is now in very extensive use on most of our British railways. These columns are made of gun metal, and the top fitting contains a small valve, which has a hole through it for the passage of steam to the glass, the bottom one having, instead of the valve, a ball testing in a small cup-shaped support immediately below the opening through which the water reaches the glass. The usual third cock is provided for biowing through when necessary. All three cocks are of Messrs. Dewrance’s well-known asbestos packed pattern, so constructed that the plugs are not in direct contact with the metal of the casings, and consequently can expand without becoming fast and immoveable as so frequently happens with plain ground-in cocks. The operation of the automatic valve