Known groomer vehicles are normally powered crawler vehicles comprising a frame extending along a first axis; and a snow grooming implement which is normally a rotary snow tiller drawn by the groomer vehicle and comprising a second frame extending predominantly crosswise to and symmetrically with respect to a second axis which, when traveling along a straight path, is aligned with the first axis, and, when traveling along a curved path, forms an angle with the first axis.
Such known hitch devices comprise an arm or so-called boom hinged to the first frame about a third axis perpendicular to the first axis, and about a fourth axis perpendicular to the first and third axis; a first actuator is connected to the first frame and the arm to adjust the position of the arm about the third axis with respect to the first frame; and at least one second actuator is connected to the first frame and the arm to adjust the position of the arm about the fourth axis.
The first actuator is often a hydraulic cylinder for lifting and lowering the arm to selectively lift and lower the rotary snow tiller with respect to the snow covering. The second actuator sets the angle between the first and second axis: when traveling along a straight path, the second actuator keeps the arm aligned with the first and second axis; and, when traveling along a curved path, the second actuator sets the arm to form a given angle with the first axis about the fourth axis.
Known hitch devices have proved highly effective, both in lifting and lowering the rotary snow tiller, and as regards maneuvering around bends and stabilizing the position of the tiller.
In some ski slope grooming conditions, however, it is necessary for the rotary snow tiller to go over an already groomed strip of the snow covering without the groomer vehicle traveling over it.
Known hitch devices allow this to be done, but force the rotary snow tiller to operate in a skew position with respect to the traveling direction, which increases energy consumption and reduces grooming width.
Moreover, when traveling along a curved path, known hitch devices are not always able to position the rotary snow tiller to cover the prints left by the groomer vehicle in the snow covering.