Select a lettered socket or an existing gear on the board, then press Small (12 teeth), Medium (20) or Large (32) below. Press another size to replace the selected gear directly. You can also drag from inventory to a socket.
Touching gears reverse direction. The smaller gear turns faster: output speed = −input speed × input teeth ÷ output teeth. A visible gap carries no power; overlaps are rejected.
Each target shows an arrow and speed in radians per second. Connect the motor to every target, then Test Mechanism.
Later levels introduce jade raised shafts. Gears on the same shaft share speed, even with different sizes. Upper gears mesh only with other upper gears.
Uncrossed belts preserve direction. Crossed belts reverse it. Use Flip Belt where available. Only explicit pulley belts transmit power.
Undo and Reset keep editing recoverable. Failed tests preserve all gears. Three stars: use the displayed optimal count; two: at most one extra gear; one: any success.
Keyboard: Select a socket in the socket list, then activate an inventory size with Enter/Space. The socket list places directly without dragging. Backspace or Z undoes while editing; Escape pauses.
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Socket list · keyboard & precise placement
Select a socket below or on the board, then press an inventory size to place or replace its gear. Remove returns it to inventory.
