Not knowing what yr/model you're working on, I'll show you an older ~2003 721D example. These are what are called Traction Kit or Traction Control. You can adjust the spring tension to add more deck weight onto the drive tire if needed.
Anyway on with the help & pics
Some older models don't have the slot for a leverage bar/tool to fit in like my 1st pic. I just use a long flat bar.
I had to change out the one on my other side with an older one that doesn't have the slot, so I have used a monkey wrench with a cheater pipe on it for better leverage. If I remember correct I had to leave the wrench quite a bit loose so as not to jam up against the fender or so once the chain is off. It's been a while. The wrench in the 2nd pic is tight and you can see it'll come even closer to the set/fender(if on) once the chain is off. If it does jam up, no biggy, it'll hold it there for ya till you put everything back together. :laughing:
Hope this is close to the model you're working on,...if not maybe it'll help others.
PS: Not sure why my pics turned out so big,...something else I need fix.
Also pull the little cotter pins at the bottom of the chains before you get into a strain with the lever/wrench-pipe,...it'll make life a little easier.