Where do I get information on rules and regulations?

I'm about to begin a career in truck repair, almost done with school, got some crummy tools in my little dinky toolbox and I want to learn as much about the industries rules and regulations so I know what to look for when inspecting a truck. In an effort to keep things simple I am trying to keep regulations that cover drivers separate from the regulations that cover the physical truck and trailers.

One of my favorite jobs was in the Army when I was put in charge of the company arms room for a few years. I learned every weapon inside and out to eliminate any doubt in my mind that a weapon I issued absolutely, positively, would go BANG when it was supposed to. After a while it became kind of a game for me to try to find damage or service affecting wear *before* it failed. (Strangely I still have dreams about M2 fifty-cals with loose trunnion blocks and M60's with bent guide rails or whittled away bolt locking lugs).

I want to do the same things with trucks, slithering around on my creeper making sure every last little detail has been inspected so the drivers know the condition of there rig and can trust me when I tell them nothing is wrong, (and also trust me when I note a deficiency and recommend a service procedure or repair).

I live in Oregon, not sure if the laws are different from state to state.

What resources can I use to research this?

[Sorry about writing a book, I think I had too much cough syrup today.]