How to choose spray boom stabilizers correctly

Spray bar stabilizers are important components that have the difficult task of keeping the spray bars always aligned.

The application of phytosanitary products is among the main steps within agricultural production, and its success depends on several factors. With the expansion of agriculture in Brazil, the use of phytosanitary products to control insects, diseases and weeds is also increasing. However, attention must be paid to the correct choice of technology to be used to ensure maximum control efficiency with minimum product losses and environmental contamination without leaving residue in the food.

Despite the importance of applying pesticides, choosing the correct technology to be used is not so simple. Many farmers imagine that an adequate use of application technology is only related to the correct choice of spray tips, however, these must be correctly arranged on the boom and operating within their pressure range, thus guaranteeing adequate uniformity of distribution, or that is, uniform application of liquid along the entire bar.

In addition to the correct use of the hydraulic tips, to obtain satisfactory uniformity in the distribution of the liquid, the spray bar must be maintained at the appropriate height in relation to the target, parallel to the ground during work and oscillate as little as possible. Therefore, in order to keep the boom level, spray boom stabilizers were developed.

These stabilizers minimize the vertical and horizontal oscillations of the bars, their amplitude is proportional to the length of the bar. Vertical oscillations are mainly caused by terrain irregularities, which alter the spray height in relation to the target and impair distribution uniformity, promoting excessive spray overlap. When the height of the bar is reduced, there is an overlap failure. Furthermore, when there are excessive oscillations, the bar may hit the ground, causing damage. Horizontal oscillations, in addition to altering the uniformity of distribution, also cause an overdose of the application.

Misalignment allows one plant to receive more product than the other, which can result in phytotoxicity to the crop, spraying inefficiency and control ineffectiveness (Sasaki, et al 2011).

A height from the spray bar to the target of 50 centimeters is commonly used. This height is mainly due to the characteristics of the spray jets and the distance between tips. In some sprayer models, according to manufacturers' recommendations, this height can be reduced, as the distance between the hydraulic tips has been reduced. In the field, it must be observed whether the height of the bar in relation to the target, along its length, is the same. The role of boom stabilizers is to maintain this height, regardless of terrain irregularities (slope, obstacles, etc.), maintaining spray quality.

Currently, there are different stabilization systems being used in hydraulic boom sprayers, which can be equipped with mechanical devices (pendulums, trapezoids and suspensions made by cables), hydraulic or hydraulic devices with electronic control.

The stabilization system called cable suspension is based on fixing the ends of a cable to the spray bar, passing this cable through a pulley that is coupled to an electric motor. In this case, if the sprayer is working on a slope, it is possible, by activating the motor, to correct the boom angle. The system that uses hydraulic devices with electronic control, known as active suspension, has ultrasound sensors at the ends of the bars to continuously capture its position in relation to the ground. These sensors send information to a system that acts on hydraulic cylinders that keep the bar parallel to the ground.

Automated boom control systems allow better control of boom height. The bar follows the undulations of the terrain and relieves the operator's tension, as there is no need to constantly monitor and adjust the height of the bar. By keeping the spray bars stabilized at the correct target height, good uniformity of spray distribution along the boom is achieved and, in some cases, drift can be avoided. Drift is the deviation of the trajectory of the drops released by the application process and which do not reach the target, therefore causing product losses, deficiency in phytosanitary treatment and consequent contamination of the environment and people close to the treated areas. Remembering that another important factor in product drift is the size of the droplet used in the application, thinner drops are more susceptible to drift, while thicker drops are more prone to running.

The use of stabilizers facilitates the use of application range markers, reduces the oscillation movements of the sprayer bars, reducing deposit variability, in addition to allowing the development of faster sprayers with larger booms, improving operational capacity during spraying. application of pesticides.

In general, to avoid possible product losses, control inefficiency, damage to the implement and various contaminations, one must pay attention to the correct functioning of the bar stabilizer, carrying out corrective maintenance if necessary and always carrying out periodic maintenance recommended by the manufacturer.

Robson Shigueaki Sasaki, Hêner Coelho, IF Minas Gerais; Mauri Martins Teixeira, UFV; Christiam Felipe Silva Maciel, Cleyton Batista de Alvarenga, UFU

Article published in issue 147 of Cultivar Máquinas.