How are Tower Cranes Built
A Tower Crane Mast Section is set into a foundation with steel pedestals. The Mast Section is is plumbed to a degree of 1:500 (ie It must not deviate more than 1 inch from plumb for every 500 inches vertical) . Concrete is poured and then the crane is ready to be erected after the curing of the concrete
A 40’ Tower crane base is being set. 16 bolts are installed. The bolts have nuts that are 2 5/16” and are torqued with a hydraulic wrench to as much as 4300 ft lbs. By comparison, the lug nuts on most cars torque to 115 ft lbs.
The process continues as mast sections are added until the needed height is achieved. The turntable (operator cabin included) is added in the same manner and is often the heaviest piece of the crane. In some applications this section is split to reduce weight on the mobile crane. This may add two hours to the crane erection process, so it is avoided when possible.
After the Turntable is installed the Tower Top is added and four large pins are added as the connecting members.
While the bolts on the Mast Section bolts are tightened, the jibs for the crane are assembled
The Counter Jib is erected as one piece. It is connected by large gates or pins at the turntable. After this connection is made it is elevated by the mobile crane to around 15 degrees above horizontal. The pendants are connected by pins with cotter pins. Then the Counter Jib is lowered to horizontal. Sometimes the Machine Package with Electrical Panel and Hoist is with the Counter Jib and other times it’s installed separately. After this, any needed Erection Ballast is installed in the Counter Jib