1. Field of the Invention
The invention relates generally to agricultural machines and more particularly to drawn agricultural machines of the type having a carrier frame for carrying processing members and being supportable on the ground, at least during transport, by means of a wheel set comprising one or more wheels.
2. Description of the Related Art
Drawn agricultural machines of this type are generally known. The carrier frame may be provided with a coupling frame which allows connection of the agricultural machine to the three-point suspension of a tractor at two lower coupling points and an upper coupling point. The coupling frame is in turn rotatable about a vertical axis of rotation relative to the carrier frame. One such agricultural machine is known from European patent application EP 1668977. This document discloses a drawn agricultural machine in the form of a rake with two rotors which are capable of being folded-in. In a transport position, the two rakes rest on the carrier frame which is supported on the ground via a wheel set having one single wheel. Owing to the fact that the described agricultural machine is connected to the tractor via a three-point linkage, extra pressure may be exerted on the lower drawbars of the tractor. This extra pressure is manually variable by varying the length of the top rod of the tractor, which is connected to the upper coupling point. The pressure on the lower drawbars depends on many factors, such as the angle made by the top rod with the lower drawbars of the tractor, the weight of the machine and the position of the centre of gravity of the machine.
A drawback of the above-mentioned agricultural machine is that the extra pressure may be difficult to adjust.
Thus, there is a particular need for a drawn agricultural machine by means of which the pressure to be applied to the lower coupling points is better manageable.