UNITRAC 1.1:

A self contained, all terrain propulsion system built around the ‘black gladiator’ chassis available from either Ebay or Core Electronics. The new chassis can be completely 3D printed from PLA and assembled with either M3 bolts (tap needed) or screws.

UNITRAC (UNIversal TRACtion system) is designed to be a universal, self contained propulsion system to suit applications ranging from exploring tight spaces to carrying/towing loads many times it's own weight. It takes inspiration from Yvon Martel's MTT-136 and Inuktun's minitrac.

The unit uses two 6v brushed gearmotors to drive it's outer track and is powered by two 18650 cells.

Supplies

Black gladiator chassis: https://core-electronics.com.au/black-gladiator-tracked-chassis.html or shorturl.at/wBJQ8

Battery tray (only needed for the ebay version): https://www.ebay.com.au/itm/324014325087?hash=item4b70c23d5f:g:yrQAAOSwvMBd90w0&frcectupt=true

ESC: shorturl.at/juxyL you can use just about any two way, 2s capable brushed speedo.

3D printed parts: https://drive.google.com/drive/folders/10HJsBIp1SIxzeYaQfu7qSTL_i4A55q4S?usp=sharing (all files are 3mf, hence the drive folder)

Step 1: Gather Components

From the Black Gladiator you will need the motors, the tracks and the 18650 holder, that's it!

You will also need some M3 screws or bolts of varying lengths.

Step 2: 3D Printed Parts

The 3mf files for all the required parts are all in the folder above, I printed mine in PLA but I would recommend ABS.

No supports are necessary but you may wish to use them for the drive gears.

You will need to print two of the 'motor holder', two of the 'motor cover' and two of the 'drive gear'.

Clean up the parts with a bit of sandpaper or a file to reduce track resistance.

Step 3: Prepare the Track

The supplied track has teeth on the inside to help it run 'true' on the supplied wheels. If you tried fitting the track to the printed wheels you may have noticed that these teeth rather get in the way. It takes ages but the best remedy is to take a pair of side cutters and remove them as close as possible to the base. then a quick 'going over' with some '60 grit should smooth out the most offensive remnants.

The Gladiator chassis comes with two tracks, unfortunately these are both too short to accommodate the new chassis so you will need to combine them into a single track roughly ... links long.

Step 4: Assembly

It's Pretty simple, just lay out the parts as shown on the left and screw them together using the the holes provided.

For the ends with the motor mounts (motors themselves only fit one way) use 25mm long screws/bolts and either more of these or 7+ mm for everything else.

The 'L' shaped mount can be interchanged with the motor cover part.

Step 5: Wiring

However you like, this is just how I did it for an RC version. It can just as easily be externally driven and the interior space used for sensors, or just ballast. Up to you!

Step 6: Incorporation

Mod it, drill holes in it, completely redo the cad, I don't care, the .step files are all available in the folder for customization purposes so make it work however you want!