Remember the 50 cubic meter concrete pad that was installed on the construction site?
Well now it is ready for its job as a tower crane base. A 6t Liebherr 100 LC tower crane will be installed.
A team of riggers from Morrow have the task of putting up the crane. Using a 100t Liebherr mobile crane and 20 tonne Terex franna crane from Gillespies Cranes.
It was an early start for the team, trucks with tower sections and the mobile crane were there when I arrived at 630am. The tower crane sections kept arriving all day. The 100t mobile crane has the task of building the crane whilst the franna crane does some lifting off the truck and helps with dual lifts to re position tower sections and counterweights.
At the start of the day the mobile crane sets up, the bigger the mobile the longer the set up, this one took about 40 minutes to set up. The mobile crane operator has a major role, as every piece of the tower crane has to be installed with this mobile.
The base tower section is being lifted off the truck, the bolts in the concrete pad will attach to the bottom of this tower section, securing it to the ground
The rigger bolts the tower section to the pad. The nuts on the bolts must be tightened with a hydraulic torque wrench to get them to the required torque.
The riggers set up a frame to work from whilst they are bolting the tower sections together. Although they are not always used, they make it easier and safer when connecting and bolting the tower sections together.
Tower sections keep being installed, the tower sections connect together and all up will reach 50 meters on this crane.
Now that the towers have all been installed its onto the next step, the A frame. On a flat top tower crane there is no A frame to install, making for quicker installation
Up goes the crane cabin, it will attach to the slewing assembly. As the crane is operated the cabin rotates with the cranes jib.
The counter jib is installed. This will hold the counterweights that balance the cranes jib and loads it lifts as well as house the electrical power board for the crane and computer for remote control operation.
Before the jib is installed, some counterweights are installed. Its very important to put the exact amount of counterweight in before putting on the jib. Too much can tip the crane in the counterjib direction. To little can tip the crane in the jib direction. Remember the purpose of the counterweights is not just to balance the loads the crane lifts but also the weight of the actual crane.
The jib is transported in pieces as its too big to travel as a single piece. When it arrives it is assembled on the ground before it is raised an in this case assembled to the crane in two pieces
first piece of the Jib is installed then the pendant that attaches to the A frame is installed
Trolley being connected to the tower crane jib, this moves up and down the jib and along with the slew and hoist control the movement of the hook block and the loads hooked up to the block.
The second part of the jib is installed
Now the counterweights go in. They simply drop into the counter jib, a steel pin running through the counterweight keeps them from dropping to the ground.
That's the fun stuff over. The rest of the install is quite slow. Now the hoist and trolley cables have to be run out as well as electrical cable that will run up to the power board on the counter jib. A specialised electrician will wire it up, the electricians used usually only do tower cranes and often have a background in plant and machinery if they didn't first start on tower cranes.
The crane is installed, before the builder can use the crane the crane must be calibrated. Limits are set on the crane to ensure that it wont lift in excess of its capacity and damage or tip the crane. The crane operator is inducted by someone from the rental company on the operation and basic maintenance of the crane.
After reading this article you may want to have a look at the tower crane anatomy for a better understanding of the parts that make up the tower crane and what they do.
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