Part 1
Rutting pivots have been a challenge for growers since the equipment was invented - in other words, this problem has been around for over 70 years.
Ruts are formed when the soil is displaced, as the wheels of the support towers (in common parlance - "carts") move across the field. This is caused by two main factors - the static load limit of the soil and the dynamic displacement.
Static Load Limit is simply a surface area parameter and is usually eliminated by installing larger wheelsets or accessories that increase the wheel contact area.
Dynamic displacement occurs as a result of the movement of the tire surface. When the tread pushes against the surface, it moves the soil with a direct force. The degree of movement depends on many factors, with a tangible effect: uneven terrain, soil type and degree of moisture, aggressive or ineffective tire tread pattern, etc. In addition, the displacement occurs due to the very geometry of the movement of the sprinkler. Every two wheels supporting the circular towers are constantly adjusted with small movements to level the sprinkler during operation.
Traditionally, the solution to the problem was considered to be the use of wheels of increasingly large sizes - until an acceptable track depth is reached. Although this method takes little account of the static load limit and does nothing at all to eliminate the dynamic displacement factor. Moreover, tires with aggressive treads often make the situation worse.
One of the options for leveling the negative impact of the irrigation system on the soil is the installation of tracks, for example, RAAFT... Static load limit is resolved by having a footprint of 520 square inches, which is more than five times the contact area of a typical tire the 11,2 x 24 series (models 525 and 526) and the 700 model, which fits the 14.9 x 24 series tires, covers an area of over 700 square inches. This fixed contact area is sufficient to cope with almost any soil condition, even with standing water in depressions.
Using RAAFT also allows you to forget about the problem of dynamic bias, which immediately sets this solution apart from many on the market today. This advantage is ensured by the special way of laying the track along which the tire rolls and thus drastically reduces the coefficient of dynamic displacement.
In fact, the soil does not move due to the axial movement, because the rolling moment occurs between the tire and the track, and not between the tire and the soil.
The cushion lies flat and remains stationary under load as the tire rolls over it. The ability of the RAAFT track to self-align and remain stationary is achieved through a unique multi-plane adaptive connection. These hinges allow the pad to tilt in any direction, but more importantly, greatly reduces the movement of the pad itself as it travels across the field. Less movement means less dynamic displacement.
Let's not forget that at the beginning of the growing season, after pre-sowing cultivation, the relief of the field is even, but it changes almost weekly. The reasons may vary. But operating the irrigation system on an unstable surface, with deep rutting, is definitely a concern. The use of caterpillars can take the edge off both sides of the problem. In addition, the tracks:
- help reduce the load on transmissions;
- protect tires from possible punctures or problem areas while driving;
- Easy to install: Tracks are pre-assembled at the factory, requiring four to six field connections to equip one tower.
- can only be installed on one or more towers - where there are alignment problems when the sprinkler is moving.
Summing up, we recall that the main measures to prevent the formation of a rut on the path of the irrigation system today include:
- installation of larger wheels,
- using more wheels per tower,
- adding a tracked system on top already available pneumatic tires.
Usually these techniques are sufficient, but there are exceptions, and in fields where deep ruts have appeared, there are frequent cases of disabling the movement of the irrigation system ("leveling error") when one of the towers stops. To avoid such situations, many new designs are initially equipped with larger diameter wheels.
What can be done with an existing track? There are many products on the market designed to solve problems with tracking the alignment of a sprinkler while driving. Problematic track sections can be filled with superabsorbent additives or just rubble; to equip the irrigation system with various wheelset designs.
A number of other options and approaches are also possible, which, if it is of interest to the readers, can be described in the following articles.
We only note that the fight against deep ruts, as well as the solution of other problems accompanying this one, are especially expensive for agricultural producers in the high season, so if this topic is relevant for you, give it maximum attention right now.