The technic tractor with a harvester which can be folded up and is activated by a little switch inside, that connects it to the drivetrain making it move with the wheels. It's also got a great suspension and steering system up front.
Might be worth putting the set no. in the description, as sometimes MOCers get picky about sets getting posted (as some people on MOCpages pretend they designed official sets...). I think you're pretty good with Technic, I like some of your designs, especially your jeeps and the R8 : ) Let's see some more MOCs!