Introduction: Knex Bi-Directional Cart

Picture of Knex Bi-Directional Cart

I made a little car which changes direction whenever it hits a wall, using only one motor.

There a seven gears involved: 4 red gears, 2 yellow gears, and 1 blue gear.
The car is 1 grey rod long, 1 red rod wide, and 1 red rod high.

Step 1: Bottom Frame and Wheels

Picture of Bottom Frame and Wheels

This is the bottom framework.

There are 2 axles connecting this frame which hold the wheels and the gears that turn in the same direction of the car. Having 2 gears is recommended, and a rubber band must be put on any wheels connected to a gear.

The framework isn't symmetrical.

Step 2: Main Axle

Picture of Main Axle

Here is where the magic happens.

At no time can both red gears mesh with the yellow gear. To achieve this, align a blue spacer next to the orange connector like in the fourth picture. You will have to readjust this when adding it onto the car.

Step 3: Top Frame

Picture of Top Frame

Build these for holding the motor... and aesthetics.

Step 4: Putting It All Together

Picture of Putting It All Together

First put in the Main Axle in between the bottom frame. The white rod (holding the yellow gear) slots into the yellow connector. It doesn't matter which way the other yellow gear points.

The top frame then is added. Make sure the yellow connectors from the main axle and top frame are on the same side.

Step 5: Motor and Done!

Picture of Motor and Done!

The motor holds a blue gear which meshes with the side Yellow Gear. Attach the green rods to the dark grey connectors and tighten this with the tan clips.

You're Done!


random_builder (author)2017-01-13

The car is cool, and the instructions are ok. I tried to make this and it switches direction before it hits the bar

Sorry for the late reply. Go back to step 2 and make the red gears further apart.

I will try that soon.

www139 (author)2016-05-10

Should really be featured! :D

sandroknexmaster (author)2015-08-16

Nice, and clear instructions!

knexfun101 (author)2015-08-10


Sorunome (author)2015-08-10

This is quite awesome indeed, great job!

Lucas The Boss (author)2015-08-09

This is pretty cool!

Lolman4000 (author)2015-08-09

I could definitely use this gear system in one of my builds.

About This Instructable




Bio: I'm into knex ball machine stuff. My favourite parts are lift/element hybrids, probably because I tried building a perpetual ball machine. It didn ... More »
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