Carrot-chasing Rabbit
"The rabbit just can't help himself!"
- When the pull string is extended in its entirety, the suction cup attached to the carrot is affixed to a surface (horizontal or vertical.) When the body of the rabbit is released, the pull string retracts, but because the carrot is fixed, the rabbit appears to “walk” across the surface. Children can pull the string and attach it to many different surface materials as well as different surface orientations.
- The toy’s underlying mechanism is a ratchet. The carrot is attached to a pull string that is connected to a wheel inside the rabbit’s body. The string tensions a spring as it is pulled. When fully tensioned, the spring triggers a pawl that releases large gears that flank the wheel. The gears are orbited by smaller gears originating at opposite poles of each larger gear. The smaller gears (one for each rabbit leg) are attached to pins. The pins have a circular orbit, which cause movement of the feet. The pull string wraps around the central wheel when retracting.
- The toy is inexpensive to construct because toys using a similar ratchet and gearbox set-up are mass produced. The rabbit and carrot should be made out of plastic to provide stability for the walking motion. The plastic that the toy is made of is durable and will withstand being dropped or falling, as these are actions that are expected to happen during play. The toy has a small part, so it should not be given to small children.
Baking Soda and Vinegar Racecar | Sound-O-Whirl
Liz Schwartz
Carnegie Mellon University
February 3, 2009