Automatic carburetor starter: 11 - air damper; 25 - bimetallic spring; 26 - pneumatic actuator of the air damper; 27 - draft for opening the air damper with an increase in the engine speed.
Air damper 11 (see picture) is held in the closed position by a bimetallic spring 25 and a system of levers, the throttle valve of the 1st chamber is ajar, i.e. it has a starting clearance that corresponds to a reliable start of a cold engine.
When starting the engine, the vacuum in the cylinders creates a significant suction effect with a limited amount of air.
After the engine starts to work, the vacuum in the intake pipeline acts on the diaphragm of the pneumatic actuator 26, which slightly opens the air damper 11 in order to enrich the combustible mixture at a minimum level when the engine warms up.
As the engine warms up, the opening of the air damper is provided by a bimetallic spring, which is heated by a resistor connected directly to the battery charge circuit.