1,721,121 research outputs found
A multibody approach applied to the study of driver injuries due to a narrow-track wheeled tractor rollover
Full text linkThis paper proposes use of the multibody approach to evaluate the severity of the injuries to the driver associated with rollover of an agricultural tractor. A simple rollover accident of a narrow-track wheeled tractor was simulated in the multibody-FEM Madymo environment and the biomechanical damage to the operator with and without 2-point pelvic restraint was analysed. The structure of the tractor was considered to be unbendable, whereas (i) infinitely rigid, (ii) clay-based and (iii) sand-based soils have been studied. The obtained results highlight the important role played by the seat belt in confining the farm operator within the safety volume maintained by the rollover protective structure (ROPS) of the tractor so that the injuries are reduced. The deformation of the soil produces lower acceleration and velocity values than those obtained with a rigid soil. On the other hand, as soil plastic deformations increase, the penetration of ROPS into the soil also increases, thus reducing the safety volume of the tractor and increasing the probability of interactions between the operator and the soil
The effects of the forward speed and air volume of an air-assisted sprayer on spray deposition in tendone trained vineyards
Full text linkThis paper reports the results of spray application trials in a tendone trained vineyard in order to evaluate the influence of forward speed and air volume on the foliar deposition of plant protection products (PPPs), maintaining roughly constant the volume applied. The trials used an air-assisted sprayer with a centrifugal fan and 4+4 adjustable fan-shaped diffusers, each with a nozzle-holder group. A full factorial experimental design was implemented, with three forward speeds and two airflow rates, organised with a randomised complete block design including three replicates. In order to consider the influence of canopy development, the tests (one spray application for each replicate of a mixture containing a water-soluble food dye as a tracer) were replicated during two phenological stages: i) the end of flowering; and ii) berry touch. Leaves were picked at random from the canopy after each spray treatment, and foliar PPP deposition was evaluated using a spectrophotometer. This analysis of foliar deposition showed that the airflow rates produced by the fan were unsuitable for the dense canopy typical of this type of vineyard. However, the special shape of the diffusers may make this sprayer effective if the main objective of pesticide applications in tendone trained table grape vineyards is to control bunch diseases
Outcomes on the Spray Profiles Produced by the Feasible Adjustments of Commonly Used Sprayers in "Tendone" Vineyards of Apulia (Southern Italy)
Full text linkThe objective of the research was to assess the outcomes on the spray patterns produced by the different feasible adjustments of two different air blast sprayers and one mist blower sprayer, commonly employed for treatments to Apulian "tendone" vineyards. The spray profiles of these machines and the respective refinements affected by the alteration of the available adjusting devices were evaluated using a test bench, suitably set up for calibrating the sprayers used inside such vines. The air blast sprayers, compared with the mist blower model, have a better chance to match the spray pattern and the canopy profile of the "tendone" vines. Furthermore, the left-right asymmetry of the spray profile is reduced only in the case of sprayers with two counter-rotating fans, under certain operating conditions. Conversely, the symmetry index worsens with the activation of the fan in the case of the air blast sprayer fitted with a single fan either with or without the air deflectors. The mist blower sprayer develops lower drawbacks, in terms of left-right asymmetry of the spray profile, even if the high "stiffness" of the spray profile makes this sprayer not particularly suitable to the changing needs of the canopy of the "tendone" vineyards. The obtained results, even if related to the analyzed sprayers, can represent an original base of reference to set up guidelines for the adjustment of sprayers used for treatments inside "tendone" vineyards, very useful for the officially authorized Apulian workshops to make sprayers inspection and calibration
Qualità delle produzioni e sistemi di meccanizzazione della raccolta delle olive. Il caso Puglia
No full textValutazione di un motore agricolo alimentato a benzina e g.p.l. con prove al banco e in pieno campo
No full textFuels actually used in agricultural machines not even allow to obtain exhaust gases which do not produce environmental damage. In fact, petrol or diesel fuel combustion can generate high percentage of carbon monoxide (CO), nitrous oxide (NOx), unburned hydrocarbon (HC). In particular, diesel fuelling produces “particulate” which is a powdery substance that remains suspended in atmosphere.
Previous experimental tests bench, on single-cylinder four-cycle engine (Lombardini mod. LA 490) fuelling both green gasoline and L.P.G. were carried out. Results showed that the elastic behaviour of the engine, as well as noises emssions, do not vary at both L.P.G. and petrol fuelling; moreover, L.P.G. fuelling allows lower values of specific fuel consumption and of pollutant emission (CO, HC) than petrol fuelling.
In a further phase, experimental tests on a self-propelled harvesting platform was carried out. The same model (LOMBARDINI LA 490) of the bench tested engine, worked on the test machine, by petrol or L.P.G. fuelling.
The field test results have substantially confirmed the bench test results: comparing L.P.G. and petrol fuelling, the first one allows lower specific fuel consumption and lower gas pollutant emission, especially when engine turns at low revolution speed which is the most frequent agricultural use.
Si riportano i risultati di una ricerca quinquennale che ha avuto lo scopo di valutare l’applicabilità dell’alimentazione a G.P.L. di motori agricoli ad accensione per scintilla di piccola potenza, sia dal punto di vista tecnico-operativo che sotto l’aspetto delle emissioni inquinanti.
Lo studio è stato condotto su un carro-raccolta semovente dotato di motore monocilindrico, a quattro tempi, con due valvole in testa, originariamente alimentato a benzina.
Nella prima fase dello studio, sono state definite alcune soluzioni meccaniche, tali da consentire una predisposizione semplice del motore anche per l’alimentazione a G.P.L. sulla macchina studiata.
Il motore della macchina è stato poi provato al banco, per la valutazione delle emissioni inquinanti in atmosfera in condizioni controllate, con l’alimentazione a benzina e a G.P.L.; successivamente, sono state effettuate prove di pieno campo, durante la raccolta delle pere.
I risultati ottenuti sono sufficientemente generalizzabili per trasformazioni di motori simili, compatibilmente ai vincoli dimensionali e di sicurezza che possono caratterizzare ciascuna macchina.
I risultati delle prove al banco sonno stati sostanzialmente confermati dalle prove di pieno campo ed evidenziano che, specie al regime di rotazione cui il motore viene prevalentemente impiegato sulla macchina, a fronte di una riduzione della coppia trascurabile, nell’alimentazione a G.P.L. la combustione risulta più regolare e le emissioni inquinanti sono più ridotte rispetto all’alimentazione a benzina. Infatti, nel funzionamento a G.P.L., al contrario di quello a benzina, le percentuali di O2, CO2, CO e HC non subiscono sensibili variazioni in funzione del numero di giri e, inoltre, i valori CO e di HC sono inferiori; anche il consumo specifico di combustibile risulta più ridotto rispetto all’alimentazione a benzina di circa il 40%.
Detti risultati sono di particolare rilievo, se si considera che il tipo di macchina studiata lavora anche in colture protette e che gli operatori sono a diretto contatto con le emissioni del motore
Indagine conoscitiva del parco trattrici a cingoli in uso in Puglia e Basilicata e delle caratteristiche tecniche degli eventuali dispositivi montati per la protezione e la ritenzione del conducente per il rischio di ribaltamento (ROPS). (vol. CD-ROM). Ricerca finanziata dall'Istituto Superiore per la Prevenzione e la Sicurezza del Lavoro - Dipartimento Tecnologia di Sicurezza
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