Types of Carbureters.—In [Fig. 32] we show another type of carbureter, which is simple in construction, and has many desirable features. The cylindrical body of the carbureter, A, has a downwardly-projecting globular extension B, at one side of which is a flange C to secure it to the pipe, and through this is the discharge opening D. This globular extension serves as the mixing chamber.
Within the cylindrical shell is an upwardly-projecting circularly-formed extension E, and the top or cap F of the cylindrical body A has a downwardly-projecting cylindrical rim G which overlaps the lower circular extension E, and it is so constructed that a very thin annular slit H is thus formed between the two parts, through which fuel oil flows from the float chamber I into the space around the central tube J which passes down through the two circular extensions E, G.
This central tube J is designed for the auxiliary air supply. It extends down to the globular base B, and has a valve K seated against its end. The stem L of the valve is vertically-movable within an adjustable stem M, and a helical spring N, capable of having its tension adjusted by the stem M, bears upwardly against the valve so as to keep it normally against the lower end of the tube J.
The auxiliary air, therefore, passes down centrally through the tube J, while the primary air supply passes through openings O, surrounding the tube J, downwardly past the slitted opening H, and thence to the discharge port D.
Surrounding the tubular projections E, G, and within the float chamber I, is the float P. This is designed to strike the bifurcated ends of a lever Q, which is hinged near its outer end, as at R, and has its short projecting end resting beneath the collar of a vertical needle valve S.
This needle valve is vertically placed within a chambered extension T at the side of the shell A, and its lower end rests within the opening of the inlet U which supplies the gasoline to the chamber I. The upper end of the valve stem passes through a plug V, through which is a vent hole W.
A spring X is used between the plug and the collar on the lower end of the needle valve, so that the valve is kept on its seat thereby, unless the gasoline in the chamber should fall so low as to cause the float to rest on the inner end of the lever Q, when the needle valve would be unseated thereby.
All the parts of this device seem to be accessible, and it is presented as an example of construction that seems to meet pretty nearly all of the ideal requirements of a device for furnishing a perfect admixture.
Surface Carbureter.—This type of carbureter also requires a float but does not have secondary air inlet mechanism. It has one striking advantage over the sprayer system, in the particular that the suction of the engine is not depended upon to draw the gasoline from the float chamber. It is much more sensitive to adjustment in the float level and needle valve than the other type.