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Innovative equipment for forage handling

Windrowing and swathing are probably the haymaking most important steps to get a good quality product. Windrowers can be classified into four categories according to their working components and their ways of working. To begin with the "star wheels", to get to the "rotary rakes", the "belt windrowing system", and the "comb" windrowers, the industry provides a wide range of solutions to suit different business needs

by Davide Facchinetti
October 2017 | Back

The increase in productivity in the haymaking mechanization was achieved basically by increasing the equipment working widths, and by adopting hydraulically operated mechanisms both to facilitate sidelines maneuvering and to allow the folding of the working components, to make them “go back to shape” for road transport. Meanwhile, the operating technical principles of the working parts have remained broadly unchanged over time.

The quality of the forage is crucial for gaining the highest quality milk, which is increasingly important not only for health and nutritional purposes, but also for an effective recognition in terms of financial value.

In this respect, the windrowing and swathing of the forage do have meaning, not only in relation to the decrease in the product’s mechanical loss, but also to limiting the soil contamination caused by the repeated and unavoidable handling the forage is subjected to during the field curing period.

While formerly the two operations were often carried out with different machineries, today we tend to use a single machine, the windrower, that can move laterally the forage forming a longitudinal pile (the swath), both to turn the forage and spread the swath on the field, adjusting, if necessary, the working components, according to needs. In addition, the definition of the most accurate feed rate is important for the reduction both of the loss of forage due to mechanical breaks, and of dirt contamination of the forage.

Except for the star wheels windrowers, the overall objective is to graze the soil surface with the ends of the working components, without touching it.

This is, moreover, pure theory: the field, even though leveled with the most advanced technologies based on the use of high precision GPS or laser, has a rough surface, which cannot be compared with a “pool table”. 

Except for machines with star wheels, it is important to focus on those equipment that minimize the inevitable contact of the working devices with the soil, bearing in mind that soil contamination facilitates the spreading of clostridial spores, which are detrimental to the production of long-ripened cheese. Almost all manufacturers of these machineries provide a wide range of products: at the international level, the most well-known brands are Pottinger, Kuhn, Fella, JF, Roc and Kverneland; in Italy as well there is a line of producers equally fierce and there are names that are often well-known also at a global level who, sometimes, also produce on behalf of foreign brands. Without pretending to be exhaustive we may quote (in strict alphabetical order) Abrimec, Da Ros Green, De Cloet, Enoagricola Rossi, Feraboli, Fiorini, Frandent, Galfrè, Morellato, Morra, Repossi, Sovema.

Windrowers can be ranked in four basic categories, according to their working components and mode characteristics: “star wheels”, the “rotary rakes”, “ belts “and finally the “combs “ ones.

Star wheel windrowers

Technically, they are the simplest, since their working components are set in motion by the reaction created during displacement when they meet the ground. Each “star” is made of a series of radially set flexible steel teeth with a slightly oblique rotation plan in respect to the forward motion, to allow the flexible teeth to use rotation to raise the forage and move it sideways. It is therefore clear that star wheel machines are the most critical from the forage “cleanliness” point of view but, on the other hand, they are characterized by their remarkable operational capabilities, as they can work up to 20 km/h, if the field is well prepared and leveled. Compared to the other categories, their additional benefits lie in their low cost and simplified maintenance. A small downside is that while they make an excellent swath, they are not equally effective in spreading it.


Rotary windrowers

This is a category that includes several models, all equipped with large forks brought by one or more rotating drums on a vertical axis. Each drum supports a series of arms arranged to form a radius at the ends of which the forks are fitted with flexible teeth in steel tendon.

The rotation of the drums is usually made by the tractor through the power take-off unit, and a shaft. Alternatively, the drive can be hydraulic or, for small models, it can come from one of the wheels laying on the ground. A set of cams placed inside the drum moves the forks to obtain their partial rotation that intercepts the forage and pushes it sideways to make the swaths.

The spreading is obtained by inverting the drums rotation direction. Rotary windrowers typically work between 9 and 15 km h, and are equally effective both as a windrower and for spreading.

These are certainly more forage friendly machines than star wheel models; although they can be adjusted to avoid contact of the teeth with the ground (if this is in optimal condition), because of the working teeth motion type, that is to say a kind of very open cycloid, the teeth provide a certain dragging of the forage on the ground during the initial phase of its handling.


Belt windrowers

Known also as endless belt types, or belt or rake types, they intercept the hay spread by combs or by different structured pickups, then they move it sideways to make the swath through a conveyor belt. They are usually suitable also for windrow turning. They are usually characterized by reduced work widths because of the size of the conveyor belt, which must be rather wide to prevent unwanted obstructions in the product flow. This is undoubtedly the ideal machine to cut clostridial pollution because, if correctly adjusted, the working component gently lifts the forage and transports it to make the swath without polluting it with the soil.

The belt windrowers main limitation is their low operational capacity due to the limited working width combined with a feed rate of “only” 4-7 km/h.

Conversely, these features make them suitable for working on not levelled and/or on considerably sloping plots.


Comb windrowers

In this case, the working component is a horizontal axis reel rotating transversely and opposite from the forward motion. Both mounted and trailed models are available; the working components movement is achieved in different ways: through the tractor’s power take-off, through one of the wheels laying on the ground, or hydraulically through the tractor’s central system, or even with an endothermic low power engine.

Anyway, the reel includes 3 or more combs parallel to each other (often 5), each of which is made of a steel rod fitted with a series of very flexible teeth in steel tendon, which stay vertical during the reel’s rotation.

The setting of the combs’ rotary axes with respect to the motion, sets up the action to be performed: if the axis is perpendicular the windrower teds or turns the hay, while to make the swath it must stay on its side.

Thanks to the characteristics of the trajectory covered by the combs (a very narrow cycloid), this windrower can lift and turn the product without dragging it, as the comb teeth enter vertically into the forage and lift it with a very short horizontal movement.

Therefore, together with the belt one, the comb windrower is particularly suitable for collecting delicate products, such as alfalfa, lentils, etc., because they both minimize damage to leaflets and stems, turned crumbly because of the drying. Here too moreover, productivity cannot be high as the average operating speed is typically between 6 and 9 km/h, with a working width that rarely exceeds 3 meters. As a final remark, it is curious that, as in other areas of agricultural mechanization, even with these machines the increase of operating speed brings a deterioration in the quality of the product obtained. As a matter of fact, it is only with the oldest concept machines, characterized by a working components movement which faithfully reproduces the manual movement of the pitchfork, that we can still obtain “clean” forage, that is to say free from ground contamination.


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