WHY SYSTEMS COLLAPSE: no tension, no system

News

Before going deeper into the topic of our newsletter, we need to take a moment to talk about “Dr. Valente”: who he is, how he became a doctor, how he differs from others… in a nutshell, why we should trust him.

Valente has more than one type of doctor in its team. The best known are undoubtedly those who make up the agent’s team, covering all the regions of Italy extensively, ensuring that customers can always benefit from a home visit to examine and work out the best solution for their field and crop. Our agents are backed up by dealers, who may be defined as ‘locals’ deeply rooted in our customer’s situation, a sort of ‘family physician’ in a village, where he knows everyone and everyone knows him. He is invariably available and has everything you need right next door; he is always ready to help you with material, advice, and installation – in short, everything you need and more. Without our valuable network of dealers, it would be impossible to cover every area of our country, each with its own specific features and characteristics that they can cater for.

Let us finish with what we might call Valente’s ‘flagship’, the installers. No, they are not our employees, but instead they are all our ‘children’. They have learnt how to assemble our systems during the training courses we have organised for them, they know all about every part, often even more than we do. This is why they regularly visit us, always with useful ideas to improve the quality of our materials and the installation process. They are the ones who make the excellent systems we sell work perfectly.

Things are not so different abroad. Here we rely entirely on our dealers, one in each of the fifty countries where Valente exports, all carefully selected and trained with enthusiasm to be a cornerstone of Valente in their own area.

In some cases, our partnerships have been in place for so long that now the owners’ son are taking over; in other cases, we have new enthusiastic partners who are determined to bring high quality technology to their countries. We then put at our customer disposal several different possibilities to help and support

After this long but important introduction, let us return to the focus of our conversation.

With last article we have barely scratched the surface of the vast subject we are committed to address: why do systems collapse?

As you may recall, we had stopped at anchoring, so let us take it from there. Two ropes depart from the anchoring; one cable and one wire if it is a head post, two cables if it is a side post. Our doctor will do something very simple: he will put his hand on the ropes.

Now, the cables must not move. Remember, the installation is a tensile structure: no tension, no installation, paraphrasing a famous advertisement.

The wires and cables must be tensioned, and to guarantee this tension there must be a fundamental tool: the super-hook. Not just as a wonderful Christmas trees made of clamps, so many that you can hardly see the cable.

Two clamps are enough and they must be placed at least twenty centimetres apart so that they can perform their job properly. In view of this, bear in mind that a clamp will never be able to do what you see in this video, i.e. tighten the system in a few seconds.

 

At this point we will open two parentheses.

The first concerns the wires and the cable: it is normal for them to elongate a little over time, but low  carbon content wires or 49-strand cable elongate too much, losing the system tension (remember the point above? No tension, no system).

We know, their tensioning is easier, so soft and ductile that you will spend your days re-tensioning the system, an option we do not recommend unless you have time for lots of extra exercise.

In all other cases we suggest using our Strukturasteel made of high carbon-content steel coated with a zinc-aluminium alloy, which ensures corrosion resistance (remember that in addition to water the installation will undergo many different treatments) and a low-elongation rate (max 5%).

As for the cable, we recommend the 19-strand one, which will be hard to tension but will guarantee you a good night’s sleep. Also because, compared to the 49-strand cable made up of “thin” wires and therefore more subject to wear, the 19-strand one has a much larger diameter of the single wires that make it up, which makes it much more long-lasting and resistant to the handling it must undergo.

The second point concerns the system itself, and more precisely the ground on which it stands. The great truth to consider is that the system moves. Or rather, the ground on which it stands moves; it is a question of possible small landslides, some of which are not even visible to the naked eye but which, just like cracks in the wall of a house, can be dangerous.

If you have the super-hook, however, there is nothing to fear; as soon as our doctor identifies a not-tensioned rope, he pulls a socket spanner from his coat pocket and in a couple of minutes fixes everything.

If you have clamps…well, how to use a tirvit wire-tensioner requires a separate article. If the clamps got rusty because of their poor quality, you’re done for, you just have to pray.

Right, after having restored the tension on our head post, we look up and follow the top wire. It is a thick, 4mm wire on which our most precious asset rests, the net. Forget all “the bigger the cable is, the better” theories; if the net rested on a rope, it would get wore in a second. So we use the wire, nothing else to add.

If, on the other hand, the doctor stands on a side post, then we have two cables. The anchoring one, as on the header, is 7mm and starts about twenty centimetres below the hood (not halfway as we sometimes see).

The transversal cable descends from the top, and this is where the DIY installer’s imagination runs wild. The best solutions obviously come from those who say “we don’t need it”, they clearly have a remote-control to regulate the wind, so that it may only blow along the direction of the rows and never across…

As you may remember, in the last newsletter we talked about the factors that affect the system. Do you also recall the point on fruit? Well, many people are convinced that only the weight of the fruit is relevant, forgetting that the fruit is attached to a tree. When we put trees down in our system, they are just small, thin and cute sticks that an amateur would never believe capable of producing so many apples. In a few years’ time, those beautiful little plants will turn into trees with leaves, branches and fruit all along the stem, so rich that they will almost form a wall.

That’s where our transversal cable comes into play: when the wind blows transversally (and it will happen during a storm, you can be sure of that), the wall of leaves will act as a barrier, increasing the stress on both the posts and the whole system, but the cable will come to their rescue by maintaining their position. The rope also has another important purpose: it is the “threshold” beyond which the net even under strong wind, will never rise.

Many DIY installers, to save money, first install the top wire and the transversal cable and then lay the net over the two, so avoiding that complicated operation of passing the net between the wire and the cable, which – despite being a very time-consuming installation step – is at the same time the proper operation to be carried out to ensure that the net has the right amount of flexibility but not full freedom.

So it is clear that having the right installer makes all the difference.

Talking about wires and cables then necessarily leads us to hoods, because it is through them that the upper structure remains connected to the posts. The hood has two fundamental tasks in the system: it covers the post end, which will potentially be in contact with the net, for at least fifteen centimetres thus preventing the abrasive surface of the post from damaging the net and, at the same time, it keeps the wires and cables locked perpendicularly to the post, imparting as much force as possible on the post (this is why it is important to design 90° systems), always in order to guarantee the correct system tensioning. We can say that both tasks are often neglected.

Covering the post end, though, is not enough, you should go down the post. It is true that the net is only on top of it, but in taking on the characteristic ‘roof’ shape of the system, it drops a little, a fact that, especially under the effect of the wind, can become a potential weakness, with the net rubbing against the post. However, the second task of the hood, that is blocking wires and cables, is undoubtedly the most neglected. The top wire and the transversal cable, which we mentioned earlier, intercept all posts of the system inside the hoods, the wire below and the cable above. The cap must therefore block them separately and independently to ease of installation (the installation of the wire, the net, and the transversal cable are three completely independent installation steps), complete blocking and protection of the net. The net is in fact compressed between the two elements (wire and cable) and therefore plastic and/or rubber washers (not to mention the nuts, washers and bolts needed to lock the wire and cable) must protect it on the point of possible abrasion, always with the aim of preserving it as long as possible.

Once again, we have come to an end. We will take up the topic of “how systems collapse” in the next post, where we will discuss: what happens to the net? How can this valuable asset have a major impact on the installation beneath it?