Abstract: A shank assembly including a rearwardly opening bracket pivotally mounting a shank. A tension link extends upwardly from a central portion of the shank and through an apertured strap. A stop member at the upper end of the link limits the downward rocking of the shank. An adjustable arm assembly including a trunnion slidably received over the tension link is pivotally connected to the bracket and adjustably compresses a down-pressure spring which encircles the link between the trunnion and the shank. Individual down-pressure adjustments can be made without affecting the transport height of the assembly.