The Locomotive Of Today

The Boiler: Blowers, Whistles. 49 from the cab, where the controlling handle is placed. The pattern shown at J is cast in gun metal and has two connec- tions for pipes inside the smokebox and a flange outside. The steam from the boiler is allowecl access to the cock through one of these pipes and passes the valve as required to the blower through the other. The valve has a screwed stem and a stuffing box is provided to prevent the escape of steam when the blower is at work. Various other types are to be met with, notably one in which a fitting is placed in the cab of the engine, and forms a small ejector for the vacuum brake as well, and steam can through it be supplied either direct to the blower or through the ejector first and then through the blower. Steam whistles are provided not only to attract attention and act as a warning for the passage or approach of trains, but are also employed as important adjuncts to the signalling arrangements of the railway, the destination and route of trains being made known by codes of signal sounds, drawn up for each district. Further, the whistle is often used as the nieans of, communicating with the driver by securing the engine end of the corcl running along the train to some suitable connection to it. The form shown in section at K consists of a gun metal bell reversed with its mouth down- wards, and with its sharp edge immediately over an annular opening in the base, through which steam issues and impinges on it, causing the bell to vibrate violently and give out sound; the smaller the bell the shriller the sound, and vice versa, the 1 arger, the deeper. The valve admitting steam to the whistle is kept closed by the pressure of the steam in the boiler, and to open it a lever is provided in the cab, to which a cord is often attached. To withdraw the valve for examination the Plug shown must be removed, and it can then be taken out. Another style of whistle is shown at L. It is similar in its action to above, but different in shape. Instead of using a large bell to deepen the sound a long pipe is employed with the same result. The action of the controlling gear can be easily followed from the sketch, as also the connection for the communication cord which comes in over suitable pulleys from the train. Many railways fit two whistles on their locomotives, one for signalling purposes, and a second for warnings only. When the whistle is placed on the cab roof—which is, perhaps, the best place to be found for it—the valves are arranged to work vertically with the gear above the whistle. There are many other fittings on the boilers of loco- motives, but most of them are for the brakes or other special appliances, and these will be described in their proper place. 4