in the description of the puzzle, it says that you cant simply undo a move, how does this happen?

anyone have an idea?

I did a quick google, and didn't find any information at all on this puzzle, then I searched the puzzle database only to return no results.

http://puzzlepalace.com/viewPuzzle.php5?id=200605

some info from the maker...


Gear Head Puzzle - a more complex gear up puzzle.

He says its like the differential gear in a car.

I didn't think that was the puzzle QUINBLZ was talking about. It doesn't have any special features to prevent you from undoing a move.

But now that you mention it, it is unintuitively hard to go back. I'll be happy to post some pictures if this is really the puzzle you were asking about.

thats what i was talking about, his description implies that there is some trick that makes it more difficult to reverse moves

Okay, here's an illustration of why it's hard to get back where you started.

Gear Up has four moving layers, but each layer is made of two thicknesses of acrylic sheet, so it looks a bit like an 8-layer puzzle.

Start: To verify when the puzzle is solved, the protruding tabs have notches on them. When the puzzle is perfectly solved you can look through all eight layers of acrylic like this...



First move: Holding the bottom two layers together, I turn the first layer anticlockwise. The second layer slowly follows. Due to the gearing, all movements require at least this much freedom. The layers must move in groups of three or four, never just one or two.



Second move: While holding the first and fourth layers steady, I push the third layer away from the fourth layer. Notice how this propels the second layer past the first layer.



Trying to go back: When I try pushing the first three layers together again, the fourth layer spins away. The fourth layer can't move without pushing the other layers apart!


There's no trick mechanism here, just sneaky psychology and efficient use of co-primes. It's hard to go back because the mechanism lures the user into doing the wrong thing. The intuitive pairing of the front-two layers or the back-two layers tempts the user into locking himself into irritating situations where all the gears seem to be "off-by-one" from being solvable.

Thanks, that was really helpful. would you say this puzzle is challenging enough to be worth the investment?

Gear Up is sold-out AFAIK. You can get about two-thirds of the same experience by solving an Enigma (aka: Combinescion). The basic challenge is similar, but Gear Up adds complexity.

I don't recommend you choose any particular George Miller puzzle just for the challenge. Although some of them are pretty challenging, you really need to appreciate them on other levels. Some are handcrafted, some behave in offbeat ways, some exhibit interesting mathematics or illustrate some unusual premise.

A good illustration of this is Three Card Burr. At $5 the buyer isn't paying for expensive materials, and certainly doesn't get any. It's just three playing cards and a piece of plastic. Once it's solved, it can't be disassembled and solved again. A bad value? No, it's an excellent specimen for those who appreciate how George Miller could make three perfectly ordinary cards do something so amazingly quirky.