CATALOGUE OF THE MECHANICAL ENGINEERING COLLECTION. 49 



2. Compression. — When the intake or downward stroke is com- 

 plete, the valve openings have moved past each other and past the 

 intake manifold opening — in other words, the ports have closed, and 

 the upward stroke of the piston compresses the gasoline vapor. This 

 compression continues until the piston reaches the limit of its upward 

 travel when — 



3. Power. — At this moment a spark occurs at the spark-plug points, 

 situated directly above the center of the piston, and the expansion 

 of the ignited gasoline vapor forces the piston downward, turning 

 the crankshaft. 



4. Exhaust. — The momentum of the flywheel causes the crankshaft 

 to continue to turn, and again forces the piston upward. During this 

 upward stroke the openings in the sleeve valves on the exhaust side 

 gradually come opposite each other and opposite the cylinder port 

 opening into the exhaust manifold and the burnt gas is forced out of 

 the combustion chamber. 



The sleeve-valve gasoline engine was developed by Charles Y. 

 Knight, of Chicago, 111., and was patented in 1903. An engine was 

 first installed in 1905 in an automobile built in the factory of the 

 Garford Co., Elyria, Ohio. The following year it was adopted by 

 the Daimler Automobile Co., of England; later by Panhard, of 

 France; Mercedes, of Germany; and Minerva, of Belgium; and 

 rather recently by Willys and Stearns, of the United States. 



Cat. No. 307,212 U.S.N.M. 



Four-Cylinder Gasoline Automobile Engine, 1921. Sectioned and Oper- 

 ated. Made and Presented by The Autocar Co. 



This engine is the most recent design of The Autocar Co. for use 

 in its automobile trucks. It is of four-cycle, poppet-valve type, 

 water-cooled, with the cylinders cast in block with removable cylinder 

 head. On the left-hand side of the engine are located the water 

 pump, magneto, oil gauge, and oil-filler cap; and on the right-hand 

 side, the carbureter, governor, and valve adjustments. The dimen- 

 sions of the cylinders are 4^-inch bore and 5^-inch stroke, giving a 

 horsepower of 28.9 (A. L. A. M. rating). The crank shaft is counter- 

 balanced and mounted on two*annular ball bearings and has no center 

 bearing ; the front bearing is 100 per cent oversize, and the rear bear- 

 ing twice the size of the front, so as to carry the additional weight of 

 the flywheel. This is a departure from general design, for, although 

 ball bearings have been considered the ideal bearings for crank shaft 

 mountings, it was difficult to maintain the alignment of the pistons 

 on account of the whip or spring of the crank shaft when running at 

 high speed. By use of a short crank shaft, due to block cylinder cast- 

 52103—22 4 



