... is composed by column, boom, guider block, trolley, elevator, extend, column rotator, trolley driver, etc. LH3550 manipulator (Inner and outer ... is composed by column, boom, guider block, trolley, elevator, extend, column rotator, trolley driver, etc.The column, boom, guider block ... . There is manual lock also.There are safe hooks on trolley, which can prevent the machine from over turning. And ...