Then again, I suppose that if you were speaking metaphorically with the individual components each representing respective cogs in the chain, you could use "gears" in that context. But I think it's a stretch.
Cornfed gets the cigar for his "collective noun" answer. I'll buy that. :)
I actually know a couple of reviewers who use "gears" improperly in print, so it's no wonder that folks are confused as to the term's proper usage.