If you're hauling hazmat, missing hazmat signs are a federal offense. If you're NOT hauling hazmat, you don't even need the placard frames.
Operating a truck should have no health consequences if done correctly. Hazmat drivers have no contact with hazardous materials if the trailers are packed and loaded correctly.
When they say "hazardous commodity" they're usually talking about hazardous materials in bulk. The first thing that comes to my mind is carbon monoxide in a tube trailer. Most people think, "carbon monoxide? Why would you want THAT?" Carbon monoxide has a lot of uses in the chemical industry, and it's a good fuel...so there's a lot of carbon monoxide going down the roads in trailers. The problem with it is, it's highly flammable and very toxic to boot. It is therefore a Hazardous Material, and in trade it is a Hazardous Commodity. OTOH, if you were to put carbon monoxide in cylinders and put the cylinders in a truck, it becomes a hazardous packaged good.
It seems like you're referring to endorsements. "T" is the endorsement to pull double and triple trailers. "X" is a combination of two endorsements - Hazardous materials, and tanker.
I need some dump trailers for my business. Where might these trailers be purchased?
Polar King is a great place to buy refrigerated trailers, they offer a wide variety of trailers you can costumize from single compartment trailers to dual compartment trailers.
Big Tex Trailers and Trailers for Less offer good information about flatbed trailers. You should be able to get a good knowledge base from these websites.
Livestock trailers usually have holes in the sides and are used to haul livestock. Stock trailers are typically enclosed completely.
Youtube has trailers.
The Lost Trailers was created in 2000.
The Lost Trailers ended in 2010.
Globe Trailers was created in 1982.
The population of Globe Trailers is 2,010.