Book 25, Question 5
How does a tower crane grow taller as the building grows?
A tower crane stands on a tall mast.
To climb higher, a special frame slips around the mast, lifts the top section of the crane, and lets workers slide a new piece of mast into the gap. The crane then rests on its taller mast. A counterweight at the back balances the load being lifted at the front. Operators work from a cab or by remote.