3749035 is referenced by 82 patents and cites 7 patents.

A precision depth planter including a plurality of furrow-forming units mounted on a main frame for relative vertical movement, each unit including a pair of depth gauge wheels for carrying the unit and for regulating the depth of the furrow formed thereby. A seed dispensing unit is mounted on the frame directly above each furrow-forming unit and includes a seed container and selecting mechanism for delivering seeds to the furrow, the several selecting mechanisms being commonly driven from a drive shaft extending transversely between the dispensing units. A separate hydraulic cylinder acts on each furrow-forming unit to maintain a constant force on said unit regardless of the position thereof relative to the main frame. A ground-engaging sensing unit mounted on the planter frame measures soil hardness and in conjunction with a hydraulic control valve acts to vary the force exerted by the hydraulic cylinders to maintain a uniform planting depth irrespective of variations in soil hardness.

Title
Precision depth seed planter
Application Number
05/101,916
Publication Number
3749035
Application Date
December 28, 1970
Publication Date
July 31, 1973
Inventor
Johnson Leslie William
Cayton David Walter
Assignee
Deere & Company
IPC
A01c 05/00
A01C 07/00
A01C 07/20
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