An agricultural vehicle includes a chassis and a header carried by thechassis. Theheader includes: a header frame； a cutter movably coupled to the header frame；a reel armpivotably coupled to the header frame； a reel carried by the reel arm andincluding a plurality oftines； a variable displacement fluid cylinder including an interior chamber, afirst piston linked tothe reel arm placed within the interior chamber and a second piston placedwithin the interiorchamber, the interior chamber defining a shared volume between the firstpiston and the secondpiston； and a piston driver linked to the cutter and configured to translatemovement of the cutterrelative to the header frame into displacement of the second piston within theinterior chamber.
