Ny-Lint Mobile Dragline Conversion

[Rvjimd]

Guys,

I'm trying to improve the crawler on my crane. I decided to try the "Z" style drive tumbler. My question, do the lower idlers help keep the tracks centered?

Here is a pic of what I'm trying to do. Not sure what it is on? Old something?



Anyone have any drawings of the idlers for something like this? Why are some like this and other like center wheel and knobs on the driver?

Thanks, Jim