Chain Drive Question

[Grommit]

Originally Posted by ahecht

I'll add in another plug for the adjustable sprocket-box that 190 has used the past few years:

The black line is the chain, the two larger sprockets are idlers, and the smaller sprocket is attached to the motor. On the bottom of the image, you can see the chain returning. By tightening or loosening the bolt, we can adjust the tension. Also, this design assures that we have a full 180 degrees of wrap around the motor's sprocket (this image isn's quite accurate).

The other nice thing is that by flipping this design around on the other side of the robot, and driving the lower part of the chain, we can have both motors driving in the same direction when we drive forward:
EDIT: Just to clarify, on each side, there are two identical lexan plates, one on either side of the sprocket. Therefore the adjustable sprocket is actually supported by two bolts, which need to be adjusted together.

That's a great way to keep the chain tensioned! I was curious about your bolt: did you have trouble with the bolt loosening in the competition? Did you use some kind of solution inside to increase friction so the bolt wouldn't slip? Or was that not a problem anyways? Also, was the sprocket shaft on a sliding slot or was there some other way to move the sprocket along?

We might consider something along those lines next year, especially if we added another pair of wheels. It would avoid using three sprockets on a shaft, one for drive and one to each other wheel: we could drive off one of the other two without sacrificing the 180 degrees of chain contact.

Very well implemented idea, thanks for sharing it.