Patent ID: 7540332

Claim:
An agricultural implement comprising: an implement frame having two opposing sides configured to support at least one ground engaging tool and move between a first height, a second height and a third height, from a supporting surface; a rock shaft which includes a central body, a first connection flange and a second connection flange; a hydraulic cylinder having a rod end and a head chamber; said first connection flange is pivotally attached to said rod end of said hydraulic cylinder; a first side of the said two sides of said implement frame is pivotally connected to said central body of the rockshaft; said second connection flange is pivotally attached to a tool bar and a front tire assembly; a mounting plate is connected to the second side of the said two sides of said implement frame; said head chamber of said hydraulic cylinder is attached to said mounting plate; a rear wheel assembly is pivotally attached to said mounting plate; and said hydraulic cylinder is configured to move the frame between the first position, the second position and the third position; and a depth stop valve in communication with said hydraulic cylinder, the depth stop valve having a bypass configured to allow controlled movement of the hydraulic cylinder between the second position and the third position; wherein: fluid flows freely through the depth stop valve during movement of the implement frame between the first position and the second position; and fluid moves through the bypass in the depth stop valve to actuate movement of the hydraulic cylinder between the second position and the third position.