Carburator – Auxiliary Low Gear System

carburador - carburetor

This animation attempted to be more realistic in demonstrating the role of the auxiliary idle subsystem in the carburetor.

The function of the auxiliary idle and progression system is to power the engine at the lowest revs when an acceleration butterfly is closed or slightly open.

Animation of idle auxiliary subsystem of the carburetor

The lowering of the piston produces vacuum -depression- inside the engine cylinder. With the engine inlet valve open and the throttle closed, the depression also forms below the throttle by drawing air from the atmosphere through the idle breather. The pressure difference between the air that is in contact with the surface of the fuel in the tank and the air passing through the idle duct expels fuel in the idle ducts by making the air-fuel mixture.

The air and gasoline form a very rich mixture, which passes through the regulating needle – which controls the flow – this mixture is drawn into the cylinder by the discharge hole of the idle, providing enough fuel and oxidizer To maintain the engine speed at idle.


– Changing the color arrow represents the ratio of the air-fuel mixture;
– Cooler colors represent poorer mixtures
– More quantes colors represent richer mixtures
– The size of the arrows represents the volume of air or mixture admitted per unit time (flow rate)

Eduardo Stefanelli

Engenheiro por profissão, professor por vocação