FIELD: transport engineering; engine cooling systems. SUBSTANCE: thermostat has housing with flange for fastening to cooling system pipeline. Drive rod is connected to thermostat by one end. Flexible sealing envelope is fitted around second end of drive rod. Sealing envelope is placed in cylinder sensitive to heat. Cylinder is filled up with paraffin granules. Cylinder and sealing envelope are tightly secured to guide member. Guide member is installed for sliding on drive rod. Main valve with pull-pack spring is arranged on guide member. Pull-back spring presses main valve to seat on flange. Thickness of sealing envelope is from 25% to 5% of drive rod diameter, thanks to it size of main valve pull-back spring can be reduced and operation of thermostat improved. EFFECT: provision of smooth and quick operation of thermostat. 2 cl, 4 tbl, 8 dwg
