Why should the number of sections of the chain be used instead of the number? What are the characteristics

When the number of chain sections is even, the joints are just connected in the inner and outer chain board. The external chain board can be made into a fixed joint with one side board and the sales shaft. Locking (for the section distance chain board), lock the other side chain board. When the number of chain sections is strange, the folding section must be used. Because the chain plate of the over -chain section is affected by the additional bending moment, its strength is only about 80% of the normal chain section, so it is advisable to take the number of even numbers under the chain.