Page:Popular Science Monthly Volume 92.djvu/452

 Keep Your Engine Efficient

This new thermostat cuts off the radiator when it cools the water too much

��ONE of the large makers of motor trucks in this country equips all of his truck engines with thermostats (thermometers

��block. The other end of the shaft carries a valve which seats on a special cage space. This cage is open at the end

��inside of the water

��^To radiator

��Course of water to pumps down _^ by- pass pipe

when valve

is closed ***T iV fisk thermostat

♦-5y-pass pipe

The thermostat keeps the engine always running at its most efficient temperature

��that control the temperature of hot fluids) in the water line to control the heat of the water in the cylinder jacket, so that at all times the en- gine is operating at its most effi- cient temperature. This condition is especially impor- tant in cold weath- er, when it is diffi- cult to start the engine.

The thermostat is controlled entirely by the temperature of the w^ater in the cylinder jacket and operates to by-pass some of the water back to the pump, instead of allowing it to be cooled in passing through the radiator in the usual manner. This is only done when the water is cold, as when starting, and is equivalent to using the same water over and over again without sending it through the radiator to be cooled. As soon as the temperature rises, the thermostat auto- matically closes the by- pass pipe and allows all of the water to go through the radiator so that the engine will not eventually over- heat.

The thermostat con- sists of a series of ten metal disks mounted on a shaft fixed at its rear end to the water system casing on the top of the cylinder

��Open position of valve when engine is heated

/ Valve closed when engine , 15 cold prevents water from / going to radiator

��Thermostat fastened

at this

����The thermostat is controlled en- tirely by the temperature of the water in the cylinder jacket

��nearest the disks and is provided with an opening leading to a by- pass pipe direct to the engine water pump as shown. When the cooling water is cold, the disks are contract- ed and the valve in the end leading to the radiator is closed, thereby permitting the water to flow down the by-pass pipe into the pump and be circulated without being cooled by passing through the radiator. As the water heats up, however, the disks expand and the end of the shaft is forced forward, opening the valve leading to the radiator and at the same time closing the opening to the by-pass. When this occurs, the water passes through the radiator in the regular manner. As the temperature of the cooling water va- ries, the thermostat alternately opens and closes the by-pass so that the temperature is kept at its most effi- cient point.

No more need the electric starter whir and whir around in an at- tempt to start a frozen engine. With this contrivance, enough warm water should remain in the engine jacket to make starting a relatively easy operation.

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