About this 3D model

Basic Quadrant Drive which can be added to existing models (shafts, pulleys, screws, hand cranks, robot wheels, etc). Scale it to any size you want, it will be compatible. Very low polygon count for no particular reason. The center cutout is just to ensure that there is some clearance -- if the opposing quadrants were connected with material then the part wouldn't be able to mate with other Quadrant Drive parts.