We've all seen construction cranes pop up all over the city. I say pop up because one day there's nothing there and the next day you're wondering where that "new" crane come from. When Coast Crane was putting a crane up in my neighbour I took some time to watch how they put the whole structure together.
A large truck based crane is used to hoist up the components to make the tower or mast as a crew "tap" in the bolts to hold it together. Piece by piece they add the turntable known as a slewing unit, along with a motor unit, operator's cab, the shorter counterweight arm, the longer main jib and finally the counterweights. The process looked like an adult version of a child's Mechano set.