Happy Life GamesGear Machine Guide: How to Build a Gear Train That Works
Gear Machine gives you a motor, one or two wonderful little contraptions (a music box, a windmill, a robot, a clock) and a board full of empty pegs between them. A tray at the bottom holds a handful of gears in three sizes. Drag the right gears onto the right pegs, and power flows from the motor, tooth to tooth, until the contraptions spring to life.
It looks like a matter of filling in the gaps, but every placement has to satisfy real gear rules. A gear only turns if its teeth meet a turning gear, every mesh reverses the direction, and a loop of gears in the wrong arrangement locks the whole machine solid. Learn those three facts and the levels become a satisfying chain of deductions.
How to play
- Drag a gear from the tray onto a peg. As you get close, a dashed ring shows where it will snap.
- Read the ring color. Green means the gear will mesh with a gear already on the board. Red means it would overlap another gear and won't fit. Pale yellow means it fits but won't touch anything.
- Move or remove gears by dragging them off a peg, either to another peg or back to the tray.
- Win by getting every contraption's gear turning (and turning the correct way, when an arrow says so).
If you drop a gear where it overlaps another, it bounces back to the tray. There's no timer and no move limit, and the undo button rewinds your placements one at a time.
The three gear rules
1. Meshing depends on size
The gears come in small, medium and large. Two gears mesh only when the distance between their pegs matches the sizes of both gears. So each peg effectively wants a particular size, depending on what's next to it. A medium gear on a peg might sit uselessly in the air, while a large gear on the same peg would reach its neighbor. The green ring is your friend here: try sizes until the ring turns green.
2. Each mesh flips the direction
When two gears mesh, they turn in opposite directions. If the motor turns clockwise, the gear it drives turns counterclockwise, the next one clockwise, and so on. Small gears also spin faster than large ones, which looks great but doesn't affect the puzzle.
3. Odd loops jam
If three gears all touch each other in a triangle, the first wants the second to go one way, the second wants the third to go the other way, and the third pushes back against the first. Nothing can turn. The game shows "JAMMED!", the connected gears shudder and the whole train stops, including the contraption. Any closed loop with an odd number of gears jams. Watch for pegs that sit where a gear would touch two neighbors that are already meshed with each other.
Beginner strategy
- Start at the motor. Only a gear touching a turning gear will move, so work outward from the motor, one powered gear at a time.
- Trace a route to the contraption first. Look at the pegs and find the chain that connects the motor to the target gear. Don't place anything yet.
- Count the tray. Make sure the gears you'll need for that route are actually in the tray. If the route needs three large gears and you have two, it's the wrong route.
- Place along the route, checking for green. Each new gear should snap with a green ring and start turning right away.
From level 3 on, the most tempting route, usually the pegs that head most directly toward the contraption, is designed to fail. It might run out of the right sizes, end at a peg that can't reach the target, or force a jam. When a straight line looks too easy, look for the longer way around.
Advanced techniques
Use parity for direction arrows
From level 13, and on many later levels, a contraption's gear has an arrow showing the direction it must turn. The arrow turns green when you get it right and red, with a "WRONG WAY!" message, when you don't.
Since every mesh flips direction, count the meshes along your chain, from the motor to the target gear. An odd number of meshes means the target turns the opposite way to the motor. An even number means it turns the same way. When the arrow is wrong, a different size on the same route won't help. You need a route with one more or one fewer gear.
Spot the bait
Levels add tricks as you go. From level 2 there are extra pegs that aren't part of any solution, some of them placed as dead-end shortcuts. From level 4 the tray carries one or two spare gears you don't need. From level 6 some pegs are traps where a gear would touch two meshed gears at once and cause a jam. Don't feel you must fill every peg or use every gear. A finished machine often leaves pegs empty and gears in the tray.
Two contraptions, one motor
Level 8 is the first with two contraptions, and they come back often. Look for a gear in your chain that can branch: one gear can drive two neighbors at once, and the train splits toward both targets. Build the shared trunk first, then the two branches.
Use undo to explore
Undo keeps a long history, so it's cheap to test a route. Place three gears, see where you end up, and rewind if it leads nowhere. If the game shows "Stuck? Undo or hint", the current arrangement can no longer be finished without removing something.
Common mistakes
- Placing gears that don't touch anything. A pale-yellow ring means the gear will sit still. It isn't wrong, but it isn't helping either.
- Closing a triangle. Three mutually touching gears always jam. Leave one of those pegs empty.
- Fixing direction with the wrong tool. Swapping sizes along the same route doesn't change direction. Changing the number of gears does.
- Using every gear. Spare gears are there to tempt you.
What changes in later levels
The routes grow longer: the first ten levels need between one and four gears, and from level 41 chains of five or more are normal. Two-contraption levels and direction arrows become common. Every tenth level is labeled HARD LEVEL at the top of the board and needs an extra gear in the chain, while the level right after is a little easier.
FAQ
What does the hint do?
It shows a faint ghost of the next gear on the peg where it belongs, with a hand demonstrating the drag. If a gear you placed is in the way, the hint shows it being moved back to the tray instead.
Why is my contraption not moving?
Either the chain is broken somewhere (one gear isn't meshing), or the train is jammed. Jammed gears shudder in place.
Is every level solvable with the gears given?
Yes. Each level is checked by a solver when it's built, and the hint follows one of its shortest solutions.
What's similar?
For more puzzles about routing a connection across a board, try Pipe Connect or Light Path.