How to distinguish the quality of aluminum stage truss zero rod First, observe the two poles and see if the joint of the two poles is two non-collinear joints and there is no load. If the above two points are met, the two poles are zero poles.
Second, determine whether the nodes of the two lenses are not collinear.
Third, for a three-stroke, if the three-stroke node is loaded on one stroke and the two strokes are in a straight line, the third stroke is a...