At present, the diesel engine on some new brand combine harvesters in the domestic market still uses a mechanical oil pump in the fuel supply system for the fuel supply of the low-pressure oil circuit. Oil pumps are equipped with manual pump oil device to meet the manual pump oil, remove the air and other needs. So why use a manual pump but often not pump it? Mainly because the elastic force of the return spring is larger than the elastic force of the diaphragm spring. When the ejector pin is at the lowest point of the cam, the diaphragm is in the position, and at this time, the pressure bar is pulled and the eccentric finger can not be pressed to the edge of the draw bar assembly The bottom edge of the square hole, so it will not be able to complete the diaphragm up and down movement process, that is, pump oil process. Only when the ejector pin is in the range of the uppermost end of the cam rising stroke, that is, the ejector pin is lifted upwards and the return spring is compressed, when the pull rod assembly is pushed up by the diaphragm spring, the pressing rod is rotated and the eccentric finger passes the pull rod The square hole on the edge of the assembly depresses the draw rod assembly and diaphragm to complete the oil absorption process. Loosen the pressure rod, the diaphragm spring can once again lift the diaphragm to complete the process of pressing the fuel. Therefore, the key to manual pump oil pump is to ensure that the top of the hollow ejector pin in the cam up stroke; the maximum manual pump oil stroke, pumping oil is the best. Turn the lever by hand and confirm the feeling of the hand when the lever is pulled. If the pressure lever is pressed, the feeling of resistance is strong, and there is a feeling of sudden increase of resistance in the 1 / 2-1 / 3 stroke of the pressure lever, indicating that the cam position is suitable, as long as the pressure bar is pulled about 300-400 times Pump full filter; if there is no sense of resistance, and the strokes in the post 1 / 2-1 / 3 stroke without resistance surge, indicating the cam position is not appropriate, you can turn the key switch, idling the diesel engine once again Confirm the feeling, the general maximum idling four or five times to make the cam to a better pump oil position.