The advantage of the internal circulation structure is that the outer diameter of the nut is a delicate "circular" shape, as shown in Figure A. Therefore, it is suitable for machines with small internal space. It should be noted that there is an internal loopball screwofScrew rodThe shaft must have one end with complete teeth, and the shoulder diameter at that end must be smaller than the outer diameter of the screw shaft, otherwise the nut cannot be assembled.