 Graham sought to solve this problem by attaching the plow shanks to spring clamps, to allow them to flex freely underneath the frame of the plow.He applied for a patent on this clamp, and in 1950, obtained (referred to by the Court as the '811 patent).Shortly thereafter, he made some improvements to the clamp design by placing the hinge plate beneath the plow shank rather than above it, in order to minimize the outward motion of the shank away from the plate.