Algodoo

This gearbox is heavily (if not completely) based on Buddingsquaw's gearbox design for one of his cars. I take no credit for designing it, apart from the direction
controls.

This is a spawn engine I made a few weeks ago, but now it's got a big honkin' gearbox on it! Press the up arrow key to start the engine, holding it until red
circles start spawning in it. Then press the 1 through 4 keys to change the gear. Press enter to stop the output, and press left or right arrow keys to change
the direction of the output. Press the down arrow until the engine stops to stop the engine. All gearbox controls are toggled.

P.S.: The engine isn't very reliable, it might stop after a while running, or if you create a sudden change with the gearbox controls. Also the part that spawns the circles can pop out of the slot (it's a crappy engine!).