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Down force adjustment and lift for an opener supported from a frame by lift arms

  • US 5,163,518 A
  • Filed: 08/21/1991
  • Issued: 11/17/1992
  • Est. Priority Date: 08/21/1991
  • Status: Expired due to Term
First Claim
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1. In an agricultural implement adapted for forward movement through a field and having a transversely extending main frame supported a preselected distance above the ground, an earth-working tool for engaging and opening a furrow in the soil, lift arm structure including upper and lower lift arms pivotally connected to the frame and supporting the earth-working tool for movement vertically into and out of soil engagement, structure for raising and lowering the earth-working tool and for adjusting the down pressure of the earth-working tool when the earth-working tool is lowered into soil engagement independently of main frame height adjustments, the structure comprising:

  • a rockshaft rotatably supported by the main frame adjacent the earth-working tool;

    means projecting radially from the rockshaft under the lower lift arm for selective engagement of the lower lift arm to raise the earth-working tool upon rotation of the rockshaft in a first direction and for disengagement of the lower lift arm upon rotation of the rockshaft in the direction opposite the first direction;

    means responsive to the spacing between the means projecting and the lift arms for applying an adjustable down pressure to the earth-working tool upon rotation of the rockshaft in the direction opposite the first direction, said means responsive comprising a coil spring stretched between the upper lift arm and the means projecting radially; and

    means for rotating the rockshaft in the first direction to lift the earth-working tool upwardly relative to the frame and for rotating the rockshaft in the direction opposite the first direction for disengaging the means projecting from the lower lift arm and changing the spacing therebetween on-the-go to stretch the coil spring and thereby adjust the down pressure.

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