Harley Davidson 1936 EL Oil Pump
1936 Knucklehead Oil Pump design is new but any later changes consider minor and don't really alter the basic idea, The compact body actually hold two oil pumps driven by a single shaft. the two pumps seats back to back in two separated chambers, the front pump is the Scavenger which return oil back to the oil tank, the rear pump get oil from the oil tank by gravitation and push it into the engine. there are two tunnels on the bottom of the pump body which rout the oil into each of the two chambers, the feed pump build pressure which go up to the oil pressure indicator and meet the check valve which hold the oil from flooding the engine while the engine is not running. light pressure and the check valve is open and oil is send to the engine, in a situations where the oil pressure is too high, the by-pass valve will open and excess oil released into the side gear case...