I have built this dock crane with the intention to control several motors from a computer. The first step in the controlling program is to move the crane to its start position, irrespective of its current position. Then the controlling loop starts by raising the jib to its upper position. Thereupon the crane turns and runs to the opposite side where the jib is lowered again. The hook, that is fitted with an electromagnet, is lowered and the magnet is powered and picks up a steel ball. Hook, magnet and ball are hoisted and then jib is raised again. The crane is turned and runs back to the start position where the jib is lowered. Finally hook, magnet and ball are lowered too. The magnet lets drop the ball into the silo. From there the ball rolls over a sloped rail track back to the other side where it came from. At the end of the track the ball stops in a catcher where it activates a switch that signals the computer to restart the controlling loop.

The silo with the steel ball who is rolling back.	The catcher and the magnet position end-switch.

The crane as it was on display at the year 2000 HCC-fair in Utrecht.

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