Tower bolts should be installed from bottom to top. First, the installation is convenient. After the nut is screwed on, you can directly see whether the nut is tightened. Second, it is best to know whether the nuts are all tightened; Third, bolts with loose nuts can be clearly seen and tightened in time; Fourth, bolts without nuts are easy to find, and bolts without nuts will fall off as long as they shake.