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. 



4y() 



