A superior side fixation part and inferior side fixation part mounted in the center portion behind the outer casing, have butt hole for mounting the turning axis.
固定在外壳后方中心部位的上侧固定部件及下侧固定部件，其具有组装上述旋转轴的铰链孔；
2
Therefore, the multiport-butt of 3-D truss, as well as the stability of turning over 2-D truss were the difficulties of the lifting project.