The device has a fixed frame (1) borne by an agricultural machine, and a mobile frame (2) intended to bear spray ramps (5). A pendulum suspension connecting rod (12) of the mobile frame is provided on the fixed frame. An actuation cylinder (4) is arranged between the fixed frame and the connecting rod. A displacing unit is provided for displacing an attachment point (7) of the connecting rod under the action of the actuation cylinder to re-center the mobile frame with respect to the fixed frame when the attachment point is displaced.
