Tri-Track OpenSCAD DC motor drive line(TT motor)

This is a sub module of thing: https://www.thingiverse.com/thing:2832658

You need this library to running the module:
https://www.thingiverse.com/thing:2832698

and the drive gear mount is originally created by madmike8, thanks:
https://www.thingiverse.com/thing:1017109/#files