PRIN. OF INTERNAL COMBUSTION ENGINES - OD1619 LESSON 2/TASK 3
FIGURE 70. BELLOWSTYPE THERMOSTAT.
(3) Configurations. The two configurations of the thermostat are:
(a) The bellows type (figure 70 on the following page), which consists of a
flexible metal bellows attached to a valve. The bellows, which is sealed and
expandable, is filled with a highly volatile liquid such as ether. The bellows
chamber is contracted when the coolant is cold, holding the valve closed. The
liquid in the bellows vaporizes as the coolant is heated, causing the bellows to
expand. The bellows pull the valve open as they expand, allowing coolant to
circulate. The bellowstype thermostat is little used in modern equipment because
its great sensitivity to the pressure around it makes it inaccurate in modern
pressurized cooling systems.
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