The device operates as follows: Primary air enters the opening between the cup K and the disk-head E, passing up into the space around the oil tube H. As the spring T, around the needle valve Q, draws up the valve from its seat, oil is permitted to flow in through the duct R and fill the chamber, until the float engages with the inner end of the lever N, and raises it, thus uncovering the ejecting end of the tube H, and at the same time closing the inlet tube R.
The suction from the engine then draws air through the primary duct, as stated, and also an additional quantity through the secondary source, by way of the valve W, this valve being so regulated as to supply the requisite quantity.
The auxiliary air source serves the purpose that means should be provided to supply more than the ordinary amount of air, when running at high speeds.
From the foregoing it will be observed that a carbureter must be so constructed that it will perform a variety of work. These are: First, Automatic means for filling the float chamber when the gasoline goes below a certain level. Second, Cutting off the supply of gasoline. Third, Providing a primary supply of gasoline for spraying purposes. Fourth, Furnishing an auxiliary air supply. Fifth, Throttling means in the discharge opening.
It is thus a most wonderful contrivance, and considering that all the elements necessary to make it work satisfactorily are provided with adjustable devices, it may be seen that to make it perform correctly requires a perfect understanding of its various features.
Requirements in a Carbureter.—In view of the foregoing it might be well to know how to select a carbureter that is ideal in its operation.
First. The adjustment of the auxiliary valve should be of such a character that at the slowest speed the valve should not be lifted from its seat.
Second. It must be so arranged that it is not difficult to change the relative amount of air and gasoline.
Third. The floating chamber should be so arranged that the float will act on the lever which lifts the valve of the injecting pipe, even though the carbureter body should be tilted at an angle. This is particularly important when the carbureter is used in automobiles.
Fourth. The valves should be in such position that they are readily accessible for cleaning or for examination.