A haymaking machine comprising a frame and a rotatable processing member for crop processing. The processing member is connected with the frame and supported from the ground via a supporting device, which comprises at least one balance arm that is mounted on a substantially horizontal pivot axis and is provided with a wheel at each of its ends. During the crop processing, the wheels bear on the ground, the supporting device further being provided with an element for moving, for transport of the haymaking machine, the balance arm about its pivot axis to an oblique position in which the wheel at one of the ends of the balance arm is located at some distance from the ground. The balance arm comprises two balance arm portions that are movable relative to each other, each balance arm portion having a first end and a second end, the balance arm portions supporting the respective wheel at their first end and being interconnected at their second end.