1926-01-01

SLEEVE-VALVE ENGINES 1 260010

First sketching the history of the sleeve-valve engine, the author reviews the valve action of the Knight, discusses combustion-chamber shape and comments upon permissible compression, remarking also on the subject of carbon deposit in the sleeve-valve type of engine. Endurance tests of Knight engines are described and, in the author's opinion, should constitute a reliable guide in judging its performance characteristics. From the beginning, one of the foremost claims for the sleeve-valve engine has been that the sleeve type of valve permits much greater port openings and more rapid opening and closing of the ports. In view of this claim, it is said to be rather strange that sleeve-valve engines have not been more of a factor in speed contests; but the explanation undoubtedly is that exceedingly large valve-capacity can be obtained with poppet valves if quiet valve-action is not a consideration, according to the author.
Considering the timing of sleeve valves, it is stated that Knight sleeve-valve engines generally have a more extreme timing than poppet-valve engines; that is, the lead of the exhaust-valve opening and the lag of the inlet-valve closing are greater. The foregoing statement is enlarged upon. A recent development of Knight-engine practice in Europe has been the substitution of light steel-sleeves for the original cast-iron sleeves, which has made possible much higher engine-speeds. Illustrations of this practice are presented and the effect upon engine performance is discussed. Eventually, the wide junk-ring on the cylinder-head will be dispensed with, according to the author, and his reasons are given. Other subjects treated in detail are the balance of sleeves, the amount of power required to operate the sleeves, detonation characteristics and lubrication requirements of the sleeve-valve type of engine, the desirable clearance between sleeves and the circulation through the head-jackets. An outline, with illustrations, is then given of the types of Knight engine developed by the Mercedes Co.

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