TECNICA from a simple frame of shaped and welded tubular sections to a completely enclosed, air-conditioned, soundproof cabin that is also protected against vibration and penetration of harmful chemicals. More specifically, the simplest structures are two-post fixed or collapsible frames installed in front or rear of the driver's seat and 4-post frames, with or without a suspended platform. Cabs are more common on medium- to high-power models since the related additional economic burden compared to a simple frame is more absorbable in the overall cost of the machine. Mandatory type approval Since they have to ensure a certain level of mechanical strength and, therefore, safety in the event of rollovers, ROPS structures must be tested and consequently type-approved in accordance with what is defined by dedicated standards. The testing procedures are both dynamic and static. Both are based on the simulation principle, reproducing the stresses to which the ROPS is subjected in the event of a rollover. Dynamic tests consist of a series of shocks and compressions; precisely, to simulate rollovers, shocks are inflicted on the ROPS mounted on the complete tractor. The tractor is anchored to the ground while a cubic-shaped mass driven by pendulum motion strikes the protective structure at the points that would come into contact with the ground in the event of a rollover. The fall height of the pendulum (and thus the energy developed) is a function of the mass of the tractor, thus the severity of the impact on the ground in the event of a rollover. This procedure faithfully simulates what happens during an accident, but in its implementation by different laboratories, it has been subject to significant ap146 TECNICA Una prova statica di carico posteriore (sopra) e una di compressione verticale (sotto) di strutture di protezione sottoposte a procedura di omologazione. A static rear load test (above) and a vertical crushing test (below) of protection structures under homologation Il montaggio di una struttura di protezione omologata sui trattori agricoli è un obbligo di legge, che è entratori in vigore su tutte le categorie dalla metà degli anni ’80 del secolo scorso. Nel 1996, l’allora ISPESL (poi confluito in INAIL) ha prodotto opportune linee guida per costruire e montare dei ROPS semplificati (telai a due o a 4 montanti) sui cosiddetti “trattori usati” (https://www.inail.it/cs/internet/comunicazione/pubblicazioni/catalogo-generale/linstallazione-dei-dispositivi-di-protezione.html). Si tratta di indicazioni molto dettagliate per fabbricare e applicare queste strutture di protezione, la cui robustezza è stata accuratamente commisurata alla categoria e alla classe di massa dei mezzi alle quali sono destinate. Si cerca in tal modo di adeguare al livello di sicurezza di quelle di nuova produzione le macchine obsolete, che comunque sono tuttora pienamente operative. Le strutture di protezione per trattori usati Installing an approved protective structure on agricultural tractors is a legal requirement that has been in effect on all categories since the mid-1980s. In 1996, former ISPESL (later merged into INAIL, the National Institute for the Prevention of Accidents at Work) issued appropriate guidelines for constructing and fitting simplified ROPS (twoor four-post frames) on so-called " second-hand tractors" (https://www.inail.it/cs/internet/comunicazione/pubblicazioni/catalogo-generale/linstallazione-dei-dispositivi-di-protezione.html). It consists of highly detailed directions for manufacturing and applying these protective structures, the strength of which has been carefully commensurate with the category and mass class of the vehicles for which they are intended. This seeks to bring obsolete machinery, which, however, is still fully operational, up to the safety level of newly manufactured ones. Protection structures for second-hand tractors Strutture di protezione per trattori usati a ruote (a sinistra) e cingolati (a destra) costruite in conformità alle linee guida INAIL Protective structures for second-hand wheeled (left) and tracked (right) tractors manufactured according to INAIL guidelines
RkJQdWJsaXNoZXIy NTY4ODI=