Towed implement with height adjustable hitch

1. A towed implement for use with a work machine, comprising:

a main frame including a pivot hole and at least one hitch mounting hole;

a hitch frame coupled with the main frame, the hitch frame including a towed end and being pivotable relative to the main frame about a pivot axis at the pivot hole, the hitch frame further including a chamber having an interior periphery with a plurality of notches spaced about the interior periphery; and

a height adjustment arrangement associated with each of the main frame and the hitch frame for adjusting a height of the hitch frame, the height adjustment arrangement including a stop key positioned within the chamber of the hitch frame, the stop key having a hole arranged for receiving a fastener associated with the at least one hitch mounting hole, a cam surface, and at least one tooth extending from the cam surface, each the tooth being received in a corresponding one of the plurality of notches of the interior periphery.

2. The towed implement of claim 1 , wherein the hitch frame further includes a slot spaced apart from the pivot axis, the slot being positioned between the main frame and the chamber and having a curvature which is at a common radius relative to the pivot axis.

3. The towed implement of claim 1 , wherein the plurality of notches are spaced apart about the interior periphery at a distance therebetween corresponding to a predetermined incremental height adjustment of the implement.

4. The towed implement of claim 3 , wherein the implement is an agricultural baler, the interior periphery has 9 notches, and each notch corresponds to an incremental height adjustment of the implement of at the towed end of about 30-35 mm relative to an adjacent the notch.

5. The towed implement of claim 1 , wherein the plurality of notches are spaced apart about the interior periphery at a distance therebetween, wherein the distance between each pair of adjacent notches can be the same.

6. The towed implement of claim 1 , wherein:

the cam surface includes a plurality of generally planar reference surfaces positioned in end-to-end relationship to each other about at least a portion of the cam surface;

the chamber includes at least one generally planar abutment surface;

the fastener passing through the hole of the stop key has a longitudinal axis; and

an angular position of the stop key about the longitudinal axis determines which the reference surface abuts a corresponding the abutment surface.

7. The towed implement of claim 6 , wherein the stop key has a single tooth positioned at an apex of the cam surface, and the plurality of reference surfaces are located on opposite sides of the single tooth.

8. The towed implement of claim 1 , wherein the at least one hitch mounting hole of the main frame includes at least one of a high hitch mounting hole and a low hitch mounting hole.

9. The towed implement of claim 8 , wherein:

the main frame includes at least one pair of clamping holes spaced apart at a rotational distance that is approximately the same as a rotational distance, relative to the pivot axis, between the high hitch mounting hole and the low hitch mounting hole; and

the hitch frame includes at least one pair of clamping slots, each the clamping slot being aligned with a respective the clamping hole, and each the pair of clamping slots having a curvature which is at a common radius relative to the pivot axis.

10. The towed implement of claim 1 , wherein the chamber extends partially through the hitch frame.

11. The towed implement of claim 1 , wherein the hitch frame includes a first plate lying adjacent to the main frame and extending to the towed end, and a second plate attached to the first plate, the second plate including the chamber in which the stop key is positioned.

12. The towed implement of claim 1 , wherein the chamber extends completely through the hitch frame to the main frame.

13. The towed implement of claim 1 , wherein the towed implement comprises an agricultural round baler.