Abstract: In an agricultural implement for use in ground breaking procedures including a frame adapted to be moved over the underlying terrain in a given direction, at least one ground breaking tool, a pivot connecting the tool to the frame for pivotal movement thereon about a generally horizontal axis generally transverse to the direction of movement between a forwarding ground breaking position and a rearward inoperative position and releasable means interconnecting the tool and the frame for normally holding the tool in the forward position and for releasing the tool for movement to the rearward position upon the tools encountering resistance sufficient to damage the implement.