Rubber spring for furrow opener

摘要

A pre-stressed columnar rubber spring interposed between the pressure beam and pivoted draw bar tube of a no-till seed drill deflects under load in one direction only and the force causing increased spring deflection in the principle operational range increases to a desired maximum and then remains substantially constant or decreases slightly thereby relieving the machine of excess stresses caused by contact of coulters and openers with rocks and other field obstructions.