... Machines of over-medium diameter,such as,Tower Crane,Truck crane,and so on.3. Single-Row Crossed Roller Slewing Ring ... compact structure,light weight,small assembly-clearance,high installation-precision,and the rollers are arranged across as 1:1 proportion, so ... require bigger diameter,such as,Bucket-Wheel Excavator,wheeled Crane,Shipyard Crane,heavy-duty Truck Crane,and so on. 5.Single-Row Four ...