Unknown part on BX-25

[amigauser]

I just bought a BX1870 (sadly, with the older 90° ROPS, not the new -1 ROPS that folds all the way down. What purpose do the knobs serve? As best as I can tell, they seem to possible be an anti-rattle measure? The pins hold it solidly in place when up.

Correct, they prevent rattle when the rops is raised and the knobs are tightened