One more thing about this nose wheel and brakes thingy.
Following the checklists we set the parking brake early, then do hydraulic tests, and then later flight control tests, which involve the rudder.
What I have found is that after starting the engines the plane starts rolling forward, and I was perplexed by this. How could the parking brake be set and the plane roll away?
I think I might have figured it out.
In the engine (or before engine) startup checklist the co-pilot says, "Parking Brake". I don't check it because I know I put it on earlier in the first check list. But I got to thinking, what if the hydraulic and control checks let the pressure bleed out of the parking brake. Somehow?
So, this last time, just before starting the engines, I released the parking brake ("V" key) then pushed and held on the brakes ("B" key), then set the parking brake again ("V" key).
Viola, it worked the plane didn't move an inch.
I also found that for taxing after you release the parking brake you have to release the regular brakes as well. ("V" then "B").