But the crawler types don't have feed for  a standard dump truck feed (where the truck would back up and dump into the hopper), most of the large ones have a precursor vehicle that the trucks dump the hot mix into a line, then this other thing (don't know what it's called, never worked with one) then picks up the long thin pile of hot mix and uses a conveyer belt thing to move it to the hopper.  

Also, there are mobile mix plants for jobs that are far enough away from a static plant.