All About Engines

242 All About Engines is a groove just below the ring into which the oil can be pushed, and from which it escapes to the inside of the piston through a number of small holes. This simple expedient adds much to the internal cleanliness of the engine. One of the most interesting accessories is a piece of apparatus whiph prevents accidents through failure of the water supply to the cylinder jackets and valve chambers. From Fig. 138, Plate 23, it will be observed that the cooling water passes into a piece of apparatus like a small gasometer with a leak in the side. With a full supply of water, however, the hood or float is lifted and water pours over the edge. If the supply fails the vessel is emptied through the side hole, the float falls, the fuel supply is cut off, and an elec- tric bell calls the attention of the attendant to what has happened. By another device the amount of compressed air driving fuel into the cylinder is made to correspond with the quantity of fuel. Again, the pump supplying oil to the bearings, etc., can be worked by hand for a minute or two before the engine starts, so that the oil which drains away when the engine is resting is replaced and all rubbed surfaces are thoroughly lubricated before the first stroke of the piston. When it is remembered that there are no boilers, no vaporisers, carburettors, or sparking arrange- ments to be looked after, it will easily be seen that the amount of attention required is very much less than that for steam, gas, or petrol engines ; while since oil fuel occupies a much smaller space than