Ila Maria Corrêa

Desempenho de motor diesel com misturas de biodiesel de óleo de girassol

Objetivou-se, neste trabalho avaliar o uso de misturas de biodiesel de girassol (Helianthus annuus L.) e diesel no desempenho de um motor de ignicao por compressao, injecao direta. Os ensaios foram realizados em bancada dinamometrica utilizando-se as misturas B5, B10, B20 e B100 em comparacao ao diesel (D). Foi analisado o desempenho do motor atraves da tomada de potencia (TDP) com cada combustivel, e analisado o oleo lubrificante do motor antes e apos 96 horas de uso com B100. Os resultados obtidos foram: D (40,7 kW; 271 g/kW.h); B5 (40,3 kW; 271 g/kW.h); B10 (39,8 kW; 277 g/kW.h); B20 (40,0 kW; 277 g/kW.h) e B100 (39,8 kW; 291 g/kW.h). Concluiu-se que o uso das misturas B5, B10, B20 e B100 proporcionou reducao de no maximo 2,2 % na potencia na TDP e um aumento maximo de 7,3 %, no consumo especifico de combustivel. A analise do oleo lubrificante, antes e apos o uso com B100, detectou alteracoes aceitaveis, sendo a viscosidade, a presenca de agua e o teor de ferro os parâmetros mais expressivamente alterados.

Desempenho operacional de trator com e sem o acionamento da tração dianteira auxiliar

The factors that may have influence on tractor performance are several, inclusive tire load and inflation pressure. These factors were studied in field conditions (surface not disturbed), under four tire load, four inflation pressure with and without the use of the mechanical front wheel assist drive. A randomized complete block design with three replications was used. The tractor under evalution was submitted to a constant drawbar pull by other tractor linked with a load cell. The results showed the significant influence of load tire on the rear wheel slip and on coefficient of traction, which increased with the decreasing of the load tires. The inflation pressure influenced significantly the slip, the forward velocity and drawbar power without to show a general tendency in the behaviour. The use of mechanical front wheel assist drive showed significant advantages to the some prior parameters. The interactive effects of load tire and inflation pressure indicated that some combinations were more favourable to develop major velocity and minor slip. The characteristics concerning to engine performance (fuel consumption and speed engine) were not influenced by neither factors and/or their interactive.

Uso de software para análise de imagem em avaliação da cobertura de pulverização

The present work aimed to evaluate the smallest concentration of the tracer fluorescent Poliglow 830 YLS necessary for an adequate contrast with the plant surface, as well as to develop a process for determination of spraying coverage using the software IDRISI for imagery analysis. Three doses of the fluorescent tracer Poliglow 830 YLS (5, 12.5 and 25 g) were previously mixed to 10 g of a mancozeb formulation, diluted in 5 L of water (0.001, 0.0025 e 0.005% w.v. of tracer) and applied on Hibiscus spp, with three different sizes of drops (very large, fine and very fine). After the complete drying of the carrier, samples of leaves were collected, taken to the laboratory and analyzed under ultra-violet light, where a leaf was visually selected with light, medium and heavy deposition, for each one of the nine treatments. The smallest dose of the tracer provided a quite incipient fluorescency for visual analysis, therefore being discarded. The other leaves were photographed with digital camera, in a totally dark atmosphere, under ultra-violet illumination. With these images, a routine analysis was developed in the software IDRISI, which allowed the automation of the coverage analyses. The software IDRISI showed to be an appropriate and efficient tool in the evaluation of the spraying coverage in the plant surface studied. The largest concentration of the tracer improved the sensitivity of the analysis.

Determinação da circunferência de rolamento de pneus agrícolas utilizando dois métodos: manual e eletrônico

The dynamic rolling circumference of agricultural tires is an important parameter to take in to account during agricultural tractor performance evaluation. Two measuring methods were compared in this paper, one manual and the other using electronic instrumentation of wheel drives. Two forward speeds and five combinations of front and rear tires inflation pressure were analyzed. The results showed that the manual method gave statistically higher values than the electronic one; although the maximum absolute difference had been of 0.24%. The inflation pressure presented significant influence in measured values, while the forward speed, for tested values (3.0 and 6.0 km.h-1), showed no significant influence.

Verificação de requisitos de segurança de tratores agrícolas em alguns municípios do estado de São Paulo

A survey was held in some regions in the state of Sao Paulo aiming at evaluating safety conditions in used and brand new tractors. 487 tractors in use in 270 farms in the state of Sao Paulo were analyzed together with 31 brand new ones displayed in shops and fairs. The following were checked: the drivers seat, its accessibility, position of controls, protection against the active parts of the engine, warning signs disposal and consonance to the national and international safety regulations for highways driving. The final result showed that while the used tractors offer no comfort or security to the driver, the brand new ones seem to fulfill the requirements, mainly those related to the drivers seat and the protection of the engine active parts.

Mistura de biodiesel de sebo bovino em motor diesel durante 600 horas

Biodiesel from beef tallow has been considered a low-cost and high availability alternative due to be residue from the Brazilian livestock production, one of the worlds largest. Papers that show the use of biodiesel from beef tallow in diesel engine are rare. The aim of this study was to investigate the effect of blend of biodiesel from beef tallow (B5) in commercial diesel oil on engine performance, analyzing possible internal consequences and characteristics of lubricating oil after the prolonged use in a diesel engine. Engine performance was evaluated through tractor power take off (PTO) tests. The engine was operated for 600 hours. Power and fuel consumption were measured. Samples of lubricating oil were analyzed by the end of each 100 partial hours. At the end of the test the engine was opened and visually inspected. Analysis of engine lubricating oil has showed critical level of contamination after 400 hours but the visual inspection of engine did not detect any internal wear. The engine performance was satisfactory although there was tendency of reduction in power and increase on fuel consumption along the 600 hours.

EFEITO DA PATINAGEM DA RODA MOTRIZ DE UM TRATOR AGRÍCOLA NA COMPACTAÇÃO DO SOLO

Vehicles travelling over a crop field have become a primary source of forces compacting agricultural soils.The type of tires used by those vehicles, their physical dimensions, their displacement speed on the soil, the number of times that their tires pass by the same place, and the load those tires support are some factors which cause higher or lower degree of soil compaction. The objective of this study was to determine, under field condictions, the effect of slip of an agricultural tractor driving wheel upon the compaction of a specific type of soil. A field experiment arranged in a randomized complete block design was carried out to analyse four different levels of slip (0, 10, 20 and 30%) with five replications, in split-plots. The degree of compaction was determined through the cone index of a soil penetrometer. Fifteen samples were taken from points along the center line of the driving wheel track, and another fifteen samples were taken from points along but outside the driving wheel track on soil band not compacted by the tires. Each sample was composed by readings from the penetrometer cone index at six different depths: 25; 50; 75; 100; 125 and 150 mm. It was found that slip had influence on the degree of soil compaction up to 5 cm depth, under the conditions this study was carried out. The 30% level of slip was the one that produced significant differences on soil compaction degree. Although it was observed an increasing compacting effect from 19.2 to 31.9%, no significant differences were observed among the cone index values for the 10 to 20% slip range.

Exposição dérmica do aplicador de agrotóxicos na cultura da uva, com diferentes pulverizadores

Com este trabalho, objetivou-se avaliar a exposicao do aplicador a calda de agrotoxico, durante pulverizacao na cultura da videira, com 4 diferentes pulverizadores. Os equipamentos avaliados foram um pulverizador semi-estacionario tipico, um pulverizador de barras adaptado a uma barra semi-circular com os bicos voltados para cima, um turbopulverizador marca Hatsuta modelo cafe, com sistema de turbina adaptado para utilizacao na cultura da uva, e um turbo-pulverizador marca KO, modelo Jales, regulados pelos produtores. Para avaliacao da exposicao dermica potencial (EDP) amostradores foram distribuidos sobre 22 partes do corpo do aplicador, que pulverizou uma calda contendo 3000 ppm do cation Cu+2 durante 35 a 40 min. Em laboratorio o Cu+2 foi recuperado e quantificado e a exposicao calculada em funcao da concentracao do cation na calda. O pulverizador semi-estacionario proporcionou a maior EDP, seguido pela barra, turbo adaptado e pelo turbo original. A porcentagem do volume pulverizado que atinge o corpo do aplicador num mesmo periodo de tempo, foi mais que 89 vezes maior para o semi-estacionario, quando comparado ao turbo Jales e a barra adaptada, e 44 vezes maior quando comparado ao turbo adaptado. As areas mais expostas do corpo foram maos, cabeca e dorso para os tratorizados e a EDP foi alta em praticamente todas as regioes do corpo com o semi-estacionario. Aspectos da EDP em funcao do equipamento e da forma de utilizacao sao discutidos.

Equipamento para medição do consumo de combustível em experimentos agrícolas

E descrito e aferido (em condicoes de laboratorio) um equipamento para medicao de consumo de combustivel para uso em experimentos com maquinas agricolas. O medidor, construido com tubos-reservatorios de PVC, tubo de vidro graduado, tanque plastico de combustivel e eletrovalvulas (12 VCC), e ligado ao sistema de alimentacao do trator com mangueiras de plastico de baixa pressao, controlando-se o fluxo de combustivel mediante uma chave eletrica liga/desliga. Faz parte do conjunto um medidor de temperatura para possibilitar o calculo da densidade do combustivel, quando necessario medir seu consumo especifico. O equipamento, desenvolvido pela Secao de Maquinas de Tracao e de Potencia, e simples, economico, de facil utilizacao, e tem precisao adequada para medir consumo de combustivel variando de 5,0 a 50,0 l/h.

Avaliação da proteção de eixos cardan agrícola em campo

The power take-off (PTO) shafts, is one of the main ways to transfer power from the tractor to drive implements. To avoid accidents the PTO shaft must be covered with a protective shield device which consists of: a) cones at each end of the driveshaft; b) a protective cover along the telescopic tube; c) restraining devices (chain or other type) and d) pictograms or safety signs. The aim of this study was to verify the conditions of use of the guards for drive shafts in farms of São Paulo. From 112 tractor-implement set analyzed, 77 showed some device featured as “protection” of the drive shaft. In this research, the cones, the tubes, the restraining devices and safety signs were observed to identify the condition (integrity, damage, absence) of each part. From components analyzed, the cones and the tubes showed to be the most damage (63.6 and 71.4%, respectively). The most common damage of cones was cracks, cuts and dents. Also lashing with wire or rope and improvisations with plastic containers were found. Some tubes were incomplete, cut and found rotating free release on the drive shaft. In the case of restraint devices (little chain) and of pictograms, the absence (50.6 and 53.2%, respectively) is the most critical situation. Also improvisations of the restraining device made with wires and ropes were noticed. The low percentage of the condition “intact” points out to