... ISO approved 2,Strict quality and self-design 3,Column and boom , with safety device, heavy type 4,Anti-fall Features for ... with cold-formed welded type structure. After the annealing process and finish machining, they possess fine rigidity and strength. 2. To ... ensure safety, the boom lifting device uses a ratchet-and-pawl structure and is equipped with a fall protection device. 3. Frequency control ...