Class B CDL

to have a Class A CDL, you MUST have air brakes, combination vehicles and general knowledge.

so, if you have a class B as you say, then you already have, general knowledge, and air brakes, so all you would need is the combination vehicles

no, a class B will NOT suffice, as you'd be in violation of driving without proper documents.

 

Yeah, you'd have to have your class A permit before you can even start to operate a class A truck. The last poster is correct in that is the only written test you will have to take. The road test is a much different story, not quite as simple. Depending on which state you live in you will have to learn 3-5 different backing maneuvers and other various requirements. Good luck.

 

It actually is possible to have a Class A without air brakes, but that's a bit irrelevant here - you're going to need it, if you don't already.
To get the permit, you just need to take air brakes (if you haven't already) and combination vehicles, as stated above. Not really a whole lot to it. If you wanted to, you could also test for endorsements, such as tanker, double trailers (basically a rehash of combination vehicles).... and you could do the written for hazmat, but there's a bit more involved in getting that.

 

No, because you're talking about two different classes of vehicles. You need a permit before you can drive a combination vehicle. You can't drive a larger vehicle than what your license class allows.