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Notes on the wear of motorcycle transmission chains

the wear performance of motorcycle chains has always been the main quality control item of chain manufacturers, and also the main acceptance item of main engine supporting plants and users. The formulation and release of the industrial standard jb/t "test specification for wear performance of motorcycle transmission chains" provides chain manufacturers and users with the standards and basis for the inspection and acceptance of wear performance of motorcycle transmission chains. In the Application Manual of the latest chain drive standard (Second Edition), in addition to elaborating the main contents of the standard, some other problems of the standard are also explained. Now it is reproduced as follows:

1. The criterion for wear failure

when the chain is worn and stretched to a certain extent, it will produce climbing and tooth skipping on the sprocket. Without protection, the chain cannot mesh correctly with the sprocket when its service life is long, so the chain can only be replaced as a vulnerable part. It is usually used as the criterion of chain wear failure. Theoretically, the normal working time of the chain is 15000h, and the ratio of the wear elongation of the chain to the nominal length of the chain should be less than 3%

2. Description of the wear theory that predicts that its conductivity depends on its pipe diameter and the spiral angle loss test time and elongation of the pipe wall

the chain wear process is divided into three stages, namely, the initial wear stage, the normal wear stage and the intensified wear stage. Since the test on the aggravating wear stage is basically meaningless, the standard only specifies the test on the initial wear stage and the normal wear stage. The specified wear test time and wear elongation data are made on the basis of a large number of tests, through theoretical analysis, and taking into account the economy, comparability and practicality of the test

(1) the standard specifies that the test time in the initial wear stage is 50h. In fact, this stage mainly tests the assembly quality of the chain. If the chain has not been run in and pre pulled before leaving the factory, the assembly defects of all parts of the chain have not been eliminated, such as incorrect positioning of all parts of the chain, uneven contact with the sleeve caused by bending of the pin shaft, high local specific pressure, inclusions between parts (hinges), insufficient lubrication, etc., which can cause accelerated initial wear. On the contrary, the elongation of the chain in the initial wear stage is also very low for the chain whose quality meets the standard, has been pre stretched before leaving the factory, has been properly heat treated, and has been fully lubricated. The value of elongation at the initial wear stage specified in Table 1 is about 0.12% of the measured chain length. This data is obtained from a large number of test statistics

(2) the standard specifies that the test time in the normal wear stage is 150h. After initial wear, the original assembly defects of the chain have been basically eliminated. If the newly developed carbon fiber of the hinge parts of the chain will pass the surface heat treatment by BMW Group, the wear and elongation of the chain at this stage is extremely slow. After the 150h wear test, the wear resistance quality level of the chain can be basically reflected. The value of necessary stage elongation of normally worn waterproof materials specified in Table 1 is about 0.04% of the measured chain length, which is also obtained from a large number of test statistics

3. Measures to improve the wear resistance of the chain

improve the manufacturing accuracy of the chain parts and ensure the heat treatment quality and assembly quality of the chain parts. The chain must be pre pulled before leaving the factory. The pre lubrication of the chain before leaving the factory is very important, and high-quality grease should be selected for pre lubrication

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