The Locomotive Of Today

The Framing, Wheels, etc.: Lubricators. 157 cylinder, a lubricator being fitted to each cylinder. When no steam is admitted to the cylinders there is a partial vacuum formed every time the piston travels from the covers, and on this faet the action of this lubricator depends. The globe is filled with oil and a small hole drilled in the cover plug allows air to enter, whilst a syphon of worsted lifts the oil over into a lower chamber leading to a valve box, which has two vertical holes in it, one fitted with a lift valve. When a partial vacuum is formed by the receding piston this valve is raised by the oil acted upon by atmospheric pressure, and a small quantity enters the cylinder. On the piston returning of course the valve is closed; oil thus enters only on the one stroke. When steam is on, the pressure is naturally far in excess of that of the atmösphere, and the above described lubricator is inoperative; another system of lubrication must therefore be introduced, and the “ Roscoe,” which is a displacement lubri- cator, comes to the rescue. It is connected to the main steam pipe, and the slide valves as well as the pistons are oiled by it. At G will be seen one of this type, which is fixed to the- side of the smokebox. The oil chamber has its outlet at or near the top, closed by a screw regulating plug, which regu- lates the required. amount to be used, and also provides for a means of Alling when empty if steam should be in the steam pipe. In this arrangement an internal pipe stands vertically in the centre of the oil space with its top closed, and having a hole at the bottom. The steam acting upon the surface of the oil presses it down, whilst the air imprisoned in this pipe is compressed somewhat; then when steam is shut off this pressure is made use of to feed a further quantity of oil. The Alling hole at top and outlet at the bottom are plainly shown on the sketch. Although the two lubricators last described are still in common use, locomotives of recent build are fitted with sight- feed lubricators fixed in the cab, where they are easily accessible to the driver. In these the oil is placed in a chamber to which steam is conducted and allowed to con- dense, the oil being tliereby displaced, this then flows down a pipe where a small jet of steam meets it and carries it to the steam chest or cylinders. The displaced oil passing, drop by- drop, up through a “ sight tube” filled with the condensed water is visible, hence the name “sight feed” lubricator. The advantages of this method of oiling are, greater safety for the men, as there is no need to go round the platform when the engine is running to see if the lubricators are at work, as. is sometimes necessary with the other kinds ; economy of oil,.