I asked an A2K friend who is Chinese, and he checked, and came up with this:
"Chinese expert found these from technical books:
1. belt tracking system;
2. belt anti-snaking device
Or
1. belt centering device "
So you could take your pick. My original suggestion of the word "guide" sounds okay to me, if you want to keep it simple (but writers of technical guidebooks rarely do, it seems
![Sad](https://cdn2.able2know.org/images/v5/emoticons/icon_sad.gif)
)
Best wishes for a happy new year. McTag