Why should the pull rods of instruments and equipment be tested in operation?

Pull rod manufacturers test the pull rod (Tianyu) of instruments and equipment, one of which is operation test. The running tester is used to test the pull rod with casters, the conveyor belt tester is used to test the friction and impact between the impact plate and casters, and the continuous walking test simulation uses pulling objects to test the quality of casters, wheel frames, pull rods and so on.