Let's say I have GT2 belt mounted inside an extrusion and a carriage. But because I need the carriage to be light, I can't mount a motor onto it. So I mount the motor at the end of the extrusion. Remember, the belt doesn't move. Theoretically, is there a power transmission system that can transfer rotation to the carriage despite the fact it will move and its distance from the motor will increase and decrease? This is just something that has been bugging me, this is what I'm doing right now: http://www.openbuilds.com/builds/v-slot-belt-driven-linear-actuator-build.80/ but I'm using 20x20 extrusion and a 20 tooth pulley which has a smaller diameter than the 30 tooth shown there so it's not perfect.