1、 Whether there is crack or burr. If the joint surface is flat and smooth, such as burrs on the working surfaces of piston rings and pistons, the cylinder will be pulled; if the flywheel is cracked, the corn thresher may explode and hurt people. Check these parts, lift them in the air, tap them with a metal handle and listen to the sound to judge whether there is a crack. It is better if the sound is clear. Parts found rusty, mildewed or aged should not be purchased
2、 Whether there is deformation and whether the geometric dimension meets the requirements. If the storage method of parts is not correct, it is easy to produce deformation. For example, when checking the valve push rod, camshaft and other shaft parts, place the push rod or camshaft flat on the counter glass, rotate it for a circle, and observe the push rod or camshaft journal. If there is light leakage, it indicates that it is bent. When purchasing all kinds of formed pads, the geometric dimension and shape shall be checked.
3、 Whether the surface protective layer is intact. Many corn thresher parts are factory protected by a protective coating. If the cylinder sleeve is protected by paraffin, if the wax layer on the parts is lost, the sealing bag is damaged, and the sealing coating is cracked during purchase, it shall be replaced.
4、 Whether there is corrosion, mildew and aging. During storage, if the temperature and humidity in the warehouse do not meet the requirements or other organic solvents are stored, the metal parts will be rusted, the paper pad, cork pad and other parts will be moldy and rotten, and the rubber parts will be aged.
5、 Whether there is looseness, degumming and desoldering. Some parts are composed of more than two parts. For example, the plunger and the crank arm of the oil pump are assembled by pressing. There should be no looseness between them. When purchasing paper filter element and other parts, the grass kneader shall pay attention to whether there is degumming at the joint; when purchasing electrical parts, it shall pay attention to that there is no degumming at each thread head.
