The present invention relates to a haymaking machine, specifically a windrower, comprising a carrier structure including a main beam (1) onto which at least one side arm (2) is hinged, said side arm supporting at least one windrowing rotor (5), said rotor (5) being connected to a carrier device (12) forming an interface with a support (9) mounted on said side arm (2), said carrier device (12) providing the rotor (5) with ranges of movement such that it can follow the shape of the terrain when the machine is operating and in a working position. Said machine is characterised in that the carrier device (12) comprises an adjustment system that makes it possible to limit the movements of the rotor (5) in the working position and to block said movements in other positions, and in that the adjustment system that makes it possible to limit the movements of the rotor (5) comprises a control means consisting of a hydraulic cylinder (13).
