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Aviation History
1919
1919 - 0009.PDF
of these bearings and collects in small pockets to the depth of about J in. The cams, in revolving, dip into this oil and splash it over the cam rollers and into pockets in the rocker lever shafts. From these poikets it is led through the hollow- rocker shafts to the rocker shaft bearings. The excess oil eventually finds its way to the gear end of the camshaft housings, over the gears and down the driveshaft housing into a chamber just above the oil pump. The excess oil thrown off in the crankcase by the con necting rods collects in this same chamber when the engine is inclined, so that the propeller end of the engine is high. If the propeller end of the engine is low, this oil collects in a small sump or chamber at the propeller end of the crank- case. Immediately above the oil delivery pump is located an oil return pump consisting of three gears, and driven by the same shaft as the delivery pump, The function of this oil return pump is to draw the excess oil out of the crank- case and return it to the oil reservoir. One section of this pump draws oil from the sump at the propeller end of the crankcase and the other section draws oil from the sump at the distributor end of the crankcase. Both halves of the pump deliver oil to the connection on the left side of the oil pump body marked " Oil Out," from which point it returns to the oil reservoir. Cooling System Cooling water is circulated through the Liberty engine by means of a centrifugal pump running at one and one- half times engine speed. The capacity of this pump is 100 gal. per mm. at 1,700 r.p.m. The cooling system from the pump inlet to and including the water outlet header will hold 5£ gal. of water. The water pump is provided with a single inlet, the outside diameter of which is 2 in., and two outlets each one delivering water to a header, the two headers supplying the right and left hand cylinders respectively. Water is forced into each cylinder jacket in a tangential direction. This construction gives the water a whirling motion inside the jacket and insures uniform cooling. The water outlet pipe for each cylinder extends inside the jacket to a point very close to the exhaust valve chamber, which assures proper cooling of the exhaust valve. The cooling water then passes through a passage cored in. the intake headers. This serves to warm and further vaporise the incoming gas as well as to assist in cooling the water- Sectioned view of Liberty engine, illustrating oil distribution. Inset: The domed piston of the high- compression model. JANUARY 2, 1919 main bearing at the propeller end of the engine goes through a passage around this bearing and up through pipe leads to the propeller end of the camshaft housings. From the end of the camshaft housing it is led around the end of the cam shaft bearing through a passage drilled diametrically through Sectioned view of Liberty water pump. the bearing midway of its length. Once every revolution of the camshaft, a hole drilled through the camshaft into its hollow centre registers with the oil passage through the bearing. Lubrication of Valve Mechanism Thus once every revolution of the camshaft a small quantity of oil is forced into the hollow camshaft. The oil is led through the camshaft and out through holes drilled in it to each camshaft bearing. The excess works out at the end 9
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