A system for supporting a cutterbar of a crop harvesting header comprising: a first arm pivotably secured to the header, the first arm including a first portion configured to support the cutterbar, the first arm including a second portion including a torsion device (90, 390) having a mass of elastic material connected to an adjustment assembly, the second portion configured to be pivotably rotatable about an axis by the adjustment assembly to selectably increase or decrease a force appliable to the first portion in order to raise or lower the first portion with respect to the header; a load limiting apparatus operatively connected to the torsion device (90, 390) for limiting an amount of torsional force that is applied to the mass of elastic material by pivotable rotation of the second portion about the axis; the adjustment assembly including a second arm interconnecting the torsion device (90, 390) and a first adjustment device having a first segment, the first adjustment device configured to movably receive a connecting second adjustment device; wherein the first segment of the first adjustment device is configured to follow a predetermined path in a first direction with respect to the axis in response to movement of the second adjustment device in a first direction with respect to the first adjustment device; and wherein the first segment of the first adjustment device is configured to follow a predetermined path in a second direction with respect to the axis in response to movement of the connecting second adjustment device in a second direction opposite the first direction with respect to the first adjustment device, the system being characterized in that the second portion includes the load limiting apparatus. a first arm pivotably secured to the header, the first arm including a first portion configured to support the cutterbar, the first arm including a second portion including a torsion device (90, 390) having a mass of elastic material connected to an adjustment assembly, the second portion configured to be pivotably rotatable about an axis by the adjustment assembly to selectably increase or decrease a force appliable to the first portion in order to raise or lower the first portion with respect to the header; a load limiting apparatus operatively connected to the torsion device (90, 390) for limiting an amount of torsional force that is applied to the mass of elastic material by pivotable rotation of the second portion about the axis; the adjustment assembly including a second arm interconnecting the torsion device (90, 390) and a first adjustment device having a first segment, the first adjustment device configured to movably receive a connecting second adjustment device; wherein the first segment of the first adjustment device is configured to follow a predetermined path in a first direction with respect to the axis in response to movement of the second adjustment device in a first direction with respect to the first adjustment device; and wherein the first segment of the first adjustment device is configured to follow a predetermined path in a second direction with respect to the axis in response to movement of the connecting second adjustment device in a second direction opposite the first direction with respect to the first adjustment device, the system being characterized in that the second portion includes the load limiting apparatus.