MariyaN (X) May 26, 2012:

Regarding the article in the Free Dictionary I've just checked it and found out the the "farm machine" part is marked with the blue bar that indicates "related words", not synonyms, so I am not sure whether this particular explanation can be attributed to the word "tiller" as its' meaning. But I may be wrong.
On the other hand, all other dictionaries that I have looked this word up in explain (or translate) tiller as either a person who tills the soil (which is definitely not the case in this particular context) or as a farm instrument used for plowing, breaking up the soil.
Please do not think I insist on my translation being absolutely correct or being the only possible way to translate it, I was just trying to find out whether "tiller" would do.
By the way, you question was whether "пахотный трактор" means "tiller", and then in the discussion you say that there enough hits on "tilling tractor". Of course there are - "tilling tractor" becomes "tilling" when it has its' tiller attached. A tiller is a plow - a tractor is not. A tractor can become tilling (or ploughing) if it's used for tilling, with a tiller attached, but it cannot be a tiller.
Too many words, I'm afraid. I wanted to explain what I mean.

GaryG (asker) May 26, 2012:

From the Free Dictionary 4. tiller - a farm implement used to break up the surface of the soil (for aeration and weed control and conservation of moisture)
cultivator
*farm machine - a machine used in farming*
harrow - a cultivator that pulverizes or smooths the soil

The question is, though, whether my translation is correct. There are also 27,500 hits in Google on "tilling tractor"