7. Check whether the connected parts are loose
An accessory composed of two or more parts, which are formed by pressing, gluing or welding, and no looseness is allowed between them. For example, the plunger of the oil pump and the adjusting arm are combined by pressing.The clutch follower and the steel plate are riveted. Friction plate and steel plate are riveted or glued. The skeleton of the paper filter element and the filter paper are glued together. The wire ends of electrical equipment are welded. If it is found to be loose when purchasing, it should be replaced.
8. See if the rotating parts are flexible
When purchasing oil pump and other rotating parts assembly, Turn the pump shaft by hand, Should feel flexible and not stuck. When purchasing rolling bearings, support the inner ring of the bearing with one hand and rotate the outer ring with the other hand. The outer ring should be able to rotate quickly and freely, and then gradually stop. If the rotating parts fail to rotate, it means that the interior is corroded or deformed, do not buy it.
9. See if there are any missing parts in the assembly
Regular assembly components must be complete and intact to ensure smooth assembly and normal operation. If the individual small parts on some assembly components are missing, the assembly components will not work or even be scrapped.
10. See if the assembly marks are clear
In order to ensure that the assembly relationship of the mating parts meets the technical requirements, assembly marks are engraved on the surface of some parts (such as timing gears). If there is no mark or the mark is vague and unrecognizable, it will bring great difficulties to the assembly, or even wrong.
11. Check the mating surface for wear
If there are signs of wear and tear on the matching surface of the parts, or if the painted parts find the old paint after removing the surface paint, it is mostly a disguised piece of waste, and you can ask for a return.
12. See if the surface hardness is up to standard
The surface hardness of each fitting has specified requirements. After confirming the purchase and negotiating with the merchant, you can use the broken stubble of the hacksaw blade to test the scratches. If there is no scratches when scratching, it means that the hardness is high. The hardness with slight scratches after scratching is higher. If there are obvious traces after scratching, it means that the hardness is low. Be careful not to damage the working surface when trying to scratch.
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