Page:Motors and motor-driving (1902).djvu/290

258 cars, which works on exactly the same principle as fig. 11, but, instead of the valves being of the flap or hinged type, they take the form of conical stoppers fitting into conical holes in the inlet and delivery sides of the pump.

Before the water from the pump enters the boiler, it is usually passed through a coil of tube inside the silencer or muffler, which is a cylindrical case, into which the exhaust steam from the engine is passed before escaping into the chimney. The expansion of the steam in the silencer reduces the noise of the exhaust, and the steam with which it is filled heats the coil through which the water from the pump passes to the boiler, so that the water itself is partially heated when

it enters the boiler. This, of course, means that less heat is required from the burner to keep up the pressure of steam. The pump is at work the whole of the time the engine is running, so when the engine is requiring little steam the pump would overflow the boiler, and to obviate this a two-way cock or tap is interposed between the boiler and the pump, controlled by a handle near the driver's seat, by which he can turn the water from the pump back into the tank. A separate hand pump is fitted for filling the boiler for starting, or at any time when it requires more water when the engine is not running, but on the Locomobile a steam pump is now provided so that steam once 'up' hand pumping need not be resorted to.