1. The function of the gasoline pump is to suck the gasoline out of the oil tank and press it to the float chamber of the carburetor.
2. Gasoline pump structure: mechanically driven diaphragm type, installed on one side of the engine crankcase and driven by the eccentric wheel of the camshaft of the valve mechanism. The pump body is divided into an upper body and a lower body. The upper body is equipped with an oil inlet valve and an oil outlet valve made of zinc alloy die-casting. A gasket is clamped between the cover and the upper body to seal the oil outlet chamber. A cloth diaphragm coated with oil-resistant rubber is clamped between the upper body and the lower body with screws, and a pump oil chamber is formed above. The diaphragm and the retainer plate are locked at the upper end of the pull rod with nuts and arch upward under the action of the diaphragm spring. The lower side of the spring seat is equipped with an oil seal to prevent gasoline leakage when the diaphragm is broken. One hook end of the inner rocker arm is inserted into the square hole of the pull rod, and the other side contacts the inclined plane of the outer rocker arm and is sleeved on the rocker shaft together. One end of the shaft is equipped with a hand rocker arm for a manual oil pump.
3. Working principle: when the engine is running, when the convex tip of the eccentric pushes the outer rocker arm to swing up, it drives the inner rocker arm and makes the diaphragm go down through the pull rod, so the volume of the pump oil chamber increases, the oil pressure decreases, the oil outlet valve closes, the oil inlet valve is sucked open, and the gasoline flows into the pump oil chamber from the oil inlet pipe. When the convex tip of the eccentric leaves the outer rocker arm, the outer rocker arm will return under the action of the return spring, the inner rocker arm will disengage from the outer rocker arm drive, and the diaphragm will arch upward under the action of the spring. Therefore, the pump oil chamber volume will decrease, and the oil pressure will rise. Close the oil inlet valve and push open the oil outlet valve to input the gasoline into the carburetor through the oil outlet pipe. When oil supply is not required, because the needle valve in the float chamber is closed and the resistance in the oil outlet chamber exceeds the elastic force of the diaphragm spring, the diaphragm is lowered to the lowest position. The pump oil is wholly stopped. Before starting the engine, if there is no oil in the float chamber or there is too little oil in the float chamber, pull the rocker arm pump oil. When the float chamber is filled with gasoline, the hand-arm will form idle motion and the pump oil will stop.
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