generallee writes:
So are all the air brake gubbins just for pulling a trailer, or are the service brakes air over hydraulic? Or full air? Sorry if I missed it...The truck's service brakes are air-assisted hydraulic; they'll work without air pressure, as fully manual hydraulic. (And they work fairly well like that, if heavy, up to 30mph or so!)
But, I don't have all the gubbins for the servo's internal air brake
valve -- there's been some pieces missing for as long as I've had the
truck -- so I've added on an external replacement for that valve (it's
a footbrake valve from a DAF CF85), that will be actuated by a pushrod
from the linkage relay arm; and that changes the setup slightly, to
air-over-hydraulic with a mechanical-hydraulic backup. It's mostly a
semantics change, the end result is that pushing the brake pedal
applies the brakes, with or without air. 
This truck was also built with the option for trailer air brakes,
which was just a hand-operated brake valve on the steering column, but
will now be operated by the footbrake pedal, like a modern truck.
The relay valve was an afterthought, mostly because I could get one cheaply (Thanks, army surplus!), but it'll speed up brake response a touch.
I've also got a little park brake lever to put in the cab, to be able to apply the trailer park brake from there, which stops off at the quick-release valve first. (Not required, just means that applying the handbrake is a little bit quicker and less air dumped in the cab through the handbrake valve's little tiny vent.)
The trailer stuff is a bit academic, really, since I've only got a class 2 license for the time bean; but it had the capability originally, so I might as well! At some point in the future, I may also add a 50mm towball just to give me more options.
A few minor screw-ups, but it's still perfectly acceptable. (Misread my notes from last time, and used the wrong spacing for the "5 tons" portion. And managed to draw my base-line for the "MAX" portion crooked without noticing.)
Sure is getting cold this time of year!
I've also gotten the aluminium for making my air-tank manifolds, though I didn't bring my drill from work so I can't start making those up yet. Also now on order is the length of tube to run from compressor to air-dryer, which will be another big step forward to having the air system build pressure.
Depending on how I'm feeling tomorrow, I might pick away at a little more bodywork. It would be nice to get that passenger step supported, so it doesn't sag as badly when I put weight on it; maybe see if I can close up the gap to the door a little better, too. (I have a horrible feeling that I might have to slice some of my 'finished' step where I welded it to the pillar, and free it back up to move again. Oh well, it's only paint & metal.)