the apparatus is a spring system on forage harvester feedrolls . the upper forward feedroll has two concentric springs on each side . the outer spring is operative over the whole range of displacement . the inner spring exerts tensioning force on the feedroll only as of a certain minimal lifting of the feedroll . the rear upper feedroll has one spring on each side . this one spring has a substantially smaller spring force than the forward spring package . the feedroll supporting linkages are arranged with complementary and cooperating cam surfaces which are disposed so that , when the forward feedroll is lifted above a predetermined minimum value , the rearward feedroll is also lifted thereby without even any lifting force from the crop material passing therebelow .