Construction Crane

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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.