Depth control for ground working agricultural implements

A first sensing means for agricultural implements, a ground engaging element attachable to said implement and means to set the depth of penetration of said ground engaging element with the ground;

• said first sensing means including a first ground engaging wheel, means mounting same for rotation and castoring action, a second ground engaging wheel journalled for rotation behind and in alignment with said first ground wheel, link means extending rearwardly from said first ground engaging wheel for journalling said second ground engaging wheel for rotation, said link means being pivotally connected to said means mounting said first ground engaging wheel, for movement of said second ground engaging wheel in a vertical plane, and spring means extending between said means mounting said first ground engaging wheel and said link means intermediate the ends thereof, normally urging said second ground engaging wheel into contact with the surface of the ground, said means mounting said first ground engaging wheel including a wheel fork, a spindle spanning said fork, said wheel being journalled for rotation upon said spindle, a fork mounting shaft extending upwardly from said fork, means mounting said fork mounting shaft for castoring action of said first sensing means, said spring means including a rod pivotally connected by one end thereof to said link means, a sliding clevis secured to said wheel fork adjacent the upper end thereof, said rod slidably engaging said sliding clevis and a compression spring reacting between said sliding clevis and anchor means on said rod.

In an agricultural implement which includes a main frame, a ground engaging element mounted in said frame and means to set the depth of penetration of said ground engaging element with the ground;

• the improvement which consists of first sensing means supported by said frame and engaging the surface of the ground in advance of said ground engaging element, to sense the contour of the surface of the ground over which said first sensing means passes, second sensing means mounted in said frame and being operatively connected to said ground engaging element to sense the change in depth penetration of said ground engaging element, and switch means in said frame operatively connected to said ground engaging element for raising and lowering same relative to said frame, said first and second sensing means being operatively connected to said switch means, said means operatively connecting said first sensing means with said switch means includes a support bar pivotally connected by one end thereof to said frame, said first sensing means being supported adjacent the distal end of said support bar and extending downwardly therefrom, a crank arm pivoted to said frame and including a first and second arm extending at an angle from one another from a common locus, said first arm being operatively connected to said support arm, said second arm being operatively connected to said switch means.