Look at the top left corner of this harrow. That looks like one being used to control depth.

[Linked Image]

If it doesn't show up, try this link: http://photos.yesterdaystractors.com/gallery/uptest/a239370.jpg

“In a time of deceit telling the truth is a revolutionary act.”
― George Orwell

It's not over when you lose. It's over when you quit.