In an carburetor where a shaft is positioned within a bearing section and there is no lubricant, such as oil or water, used between the shaft and bearing section, a flow of pressurized air is directed through a passageway into the bearing section and then into a slot which extends in the circumferential direction so that air can be directed axially between the shaft and the bearing section. The flow of air prevents the entry of any alien substances, such as dust or moisture, into the space between the shaft and the bearing section.