This is the front suspension mechanism of my newly acquired Dahon Jetstream:



And this is the front suspension mechanism of my newly acquired Dahon Jetstream upside down:



And this is the big-ass nut in the middle that looks like it might be a tension and/or rebound adjuster of some sort:



Now, when I tried to negotiate this thing with a wrench, I found that it was locked as far as it would go clockwise. I was able to easily turn it a few turns out (counterclockwise,) but I was afraid that if I turned it too far, the whole thing would come apart, so I turned it back in to its clockwise locked position. With the bike on the floor, I'm able to compress the suspension about a quarter of the way through its travel with my full body weight on the handlebars.

So, what am I supposed to do with this thing? Is it actually adjustable, the same way the rear shock is adjustable?