... of column, welding arm, elevating mechanism, boom expansion mechanism, cross trimming,and electrical box. It can ... elevating stroke: 4000mmHorizontal expansion stroke: 7000mmBoom elevating speed: 1M/minBoom expansion speed: 0.12-1.2M/minSpeed control ... elementsa. Frame assembly: column, elevating mechanism, boom expansion mechanism, cross trimming, ladder.b. electrical control system ...