It will be noted, that as there is no fuel in the cylinder during the compression stroke that there is no danger from preignition from an over heated charge, nor is there trouble from decomposed fuels due to a gradually increasing temperature so often met with in oil engines that compress the entire mixture. As the clearance space is exceptionally small there is a minimum of residual gas held in the cylinder after the explosion with the result that the fuel is completely consumed, and that a full charge is taken into the cylinder. The speed and output are regulated by controlling the point in the working stroke at which the oil spray is cut off, and as this has no effect on the maximum pressure developed in the cylinder, as in the case of the ordinary gas engine control, the pressure charge under varying loads is not so severe. Because of the high compression, and the continued combustion, there is a very gradual increase of pressure. Since the amount of pure air admitted to the cylinder is the same at no load as at full load there is always sufficient air for the complete combustion of the fuel, and as there is a constant compression pressure there is a constant ignition temperature and constant quantity of the working medium. Because of the high compression obtained by the Diesel type, it has an efficiency that is far beyond that of any other form of internal combustion motor. [Illustration: Fuel Nozzle of the Koerting Diesel Engine Showing Operating Cam and Lever, and Compressed Air Connection. ] Since the fuel is introduced gradually into the combustion chamber the combustion pressure rises very slowly so that it is not an explosive engine in any sense of the word, the combustion pressure rising steadily from the compression pressure to the maximum in proportion to the supply of fuel. In the ordinary type of gas engine with a compression pressure of from 60 to 70 pounds per square inch the pressure rises abruptly to about three and one-half times the compression pressure, with a correspondingly rapid drop in the pressure on the expansion stroke. In the Diesel engine the drop of pressure in expansion is much more gradual, the indicator diagram expansion curve being nearly horizontal. The uniform pressures thus obtained result in smooth action and even driving power, obtained with no other type of engine. [Illustration: Fuel Pump of Koerting Diesel Engine with Operating Cam. ]