Creating structures the size of our Sears Tower model led to other large-scale
ideas. At left is a construction crane, perhaps of a size big enough to help
build skyscrapers. Attached to a tall but sturdy base, the horizontal arm of
the crane can pivot around in a complete circle. A dual-chain design was
incorporated so that the crane would be capable of lifting objects. A hand
crank above the crane's center pivot is used to rotate a continuous chain loop
attached to a second length of chain, at the end of which is a wrecking ball.
Due to the heavy weight of the crane arm, six large wheels and tires are used on
grey rods to form adjustable counterweights. This weight could probably be
reduced if lightweight string were used in place of the heavier K'nex chain
pieces. To provide a cushion for the rotation of the crane arm, a large wheel
and medium tire are used on the pivot axle above the crane base. The top of the
base narrows to a square of blue rods, and is heavily reinforced with extra
connectors. The model stands over five feet tall.
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