28 October 2019

The shaped cleats

From the very beginning of agricultural mechanization, the tyre has been and will be one important part for the performance from the machine to the field. In this evolution, we have gone from the iron wheels to the most modern VF tyres (low pressure that optimize the traction of the machine). In this evolution, the cleats are one decisive part that seeks the greatest possible efficiency. However, what are the needs that the tire cleats have to overcome? This is the first question engineers ask when they are designing a tire. If you are looking for traction and only traction, a cross block in the direction of travel is the most efficient. Quite the opposite situation we could have if we look for comfort in the wheel, in this way the length and closeness among cleats will give us a greater contribution of stability and comfort.

For this reason, the cleat has to pass efficiently the different conditions that we demand it. The main characteristics for a tractor tyre are: traction, comfort, self-cleaning, durability, noise and rolling stability. These characteristics are, in many cases, antagonistic to each other. As we mentioned at the beginning, traction is obtained with one type of cleat and comfort with another type. Therefore, the objective is to achieve a tyre that achieves the improvement of current performance without harming its opponent.

Nowadays, modern tractors are machines designed to carry out a lot of great efforts, but at the same time they reach high speeds, which affects the comfort and stability of a machine that is quite high in size and that works very long days on many occasions. Therefore, in design, many different variables are used to obtain the final product, and these would be the premises to be taken into account:

  • If we are looking for traction: very crossed cleats on the direction of travel and high distance between them to be able to make the necessary traction.
  • If we are looking for comfort: very close and long cleats. Better in longitudinal direction.

As these two factors are a priori opposed, all manufacturers of agricultural tyres opt for intermediate products, which are capable of meeting these two needs at a the same time as far as possible. Each manufacturer choose, some of them for straight cleats at 45 degrees or with two different levels of position (a first line at 40 degrees and a second at 50 degrees). In this case Vredestein, which is one of the solutions we prefer, makes the central area of the cleats very unit to give continuity, comfort and low rolling noise, while the final area is almost 90 degrees above the direction of travel, which acts fully on the traction. This is achieve with a smooth curvature, which makes the stability of the cleats another of its great strengths. The size of the tyre also affects the design of its cleats. A compact tractor, for work in vineyards or fruit trees, requires different performance than a 400 hp tractor for pulling with a plough. For this reason, the cleats are manufactured with the robustness required according to the size of the tyre and the size of the tyre varies according to the performance of the tractor.

The tyre sector is constantly evolving, testing different materials and componentsĺ such as the chemistry used, types of rubbers, resins, polymers, etc. in addtion to being constantly testing to seek continuous improvement and be able to have more and more an optimized tyre.

Versión en español.

No comments:

Post a Comment