Tractor safety systems and components
and components Accident data for agriculture indicate a significant downward trend in the last few years, but the number of accidents is still high. The reduction is especially noticeable in the professional agriculture sector, where state-of-the-art machinery with advanced safety systems is used
Let's start with the good news: the number of accidents in agriculture has been steadily decreasing for seven years now. The figures for the five-year period 2016-2020 show a reduction of 26.3% (from 36,199 cases in 2016 to 26,696 two years ago). If we do not consider the pandemic year, the decline is not as sharp, but still present at -8.6%. This trend is also confirmed for the current year: in the first half of the year - we are publishing Inail data, of course - there was a further drop in complaints of 2.6% (from 12,950 in 2021 to 12,612 this year). Lastly, occupational diseases, which are mostly affecting the spine, bones, soft tissue and nervous system (typically carpal tunnel syndrome), are also slowing down. However, those approximately 25,000 cases remain - estimated for 2022 - which is still too high a number, especially considering that many of the accidents are unfortunately serious, when not fatal. All the more so those involving the use of agricultural machinery, which rank first in terms of seriousness of damage. In this regard - and with this we close the statistical chapter - another statistic is interesting: the number of accidents falls more in the professional agro-mechanics sector (namely among contractors and their employees) than among farmers. Since agro-mechanical workers operate, by definition, mainly agricultural machinery, this apparent inconsistency can only be explained in one way: the use of newer machines with a much faster turnover, typical of subcontracting, plays a key role in reducing the number of accidents.
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A question of turnover. It is a fact that the machine fleet in the agro-mechanical sector is on average less old and of a higher quality level than that of the farmer who works on his own or who owns a small farm. This is both for budget reasons and also in terms of annual working hours, which in the case of agro-mechanics often exceed one thousand. As a result, tractors and equipment wear out more quickly. It follows that the average fleet of a contractor's machinery is certainly less than ten years old (for tractors and harvesting machines) and is therefore equipped not only with the accident-prevention devices required by law, but also with a series of latest-generation devices now common on high-tech tractors, but absent from older machines. It is on these that we want to focus in this quick analysis of the progress made in accident prevention.
Structural safety. As we know, the minimum safety requirements for agricultural tractors are to protect the driver against the danger of being crushed due to the vehicle rolling over (Rops) or bodies falling from above (Fops). The presence of restraint systems is also mandatory. For the first point, we should mention the presence of a cab with four or more uprights or a protective arch in the case of tractors without a cab (typically those intended for specialised crops and which, operating under vegetation, must forcibly reduce their maximum height). On the other hand, the most typical - and, unfortunately, least used - restraint systems are seat belts, which are present on all modern tractors and are also prescribed to renew the official approval on older vehicles. Another structural safety systems to be considered are the guards - also required by the regulations - for all parts that rotate rapidly or are subject to extreme temperatures (above 80 degrees, if these are positive temperatures). Thus, grilles are indispensable on tractors to protect fans, belts or other rotating parts, as well as radiators and exhausts, and gas after-treatment systems (Egr, in acronym). These are generally elements that are located under the bonnet, with the exception of the front and rear power take-offs and their cardan shafts. As is well known, these must mandatorily have non-rotating covers, usually retained by a chain latch, to be fixed to a stable element of the vehicle. Since this type of guard, and in particular the fixing chain, are prone to breakage, some manufacturers of cardan shafts have, in recent years, designed fixed chainless guards to increase the safety of one of the most accident-prone devices. As far as fans and belts are concerned, the tractor bonnet is in itself an effective protection, especially now that its opening, which used to be possible by acting on a simple lever or button, is tied to the use of a special key, which is usually also the start-up key. It should thus be impossible to access moving parts when the machine is in operation. Another recently introduced element is the battery disconnection system, which is designed to avoid fire hazards while stationary, but is also useful as an electrocution prevention measure. Finally, the presence of external controls for operating hydraulic services, three-point linkage and power take-off should be mentioned: they are usually located on the mudguards, in a position where they cannot be operated by the operator while in the danger zone.
The role of electronics. The huge increase in electronic and digital components on agricultural vehicles has certainly contributed to improving their safety by providing a series of automatisms thanks to which the danger of accidents can be averted or reduced. Many of these systems are part of the control levers (more on this later). Here, however, we dutifully mention the 'man-present' devices, which block the operation of the tractor and its functions - from the PTO to the power lift, not forgetting of course the transmission - when there is no operator at the driver's station. Thanks to a simple weight sensor installed on the seat, the presence of a man on board has become indispensable, making high-risk operations such as hitching up implements impossible without someone controlling the moving vehicle. A similar concept applies to the parking brake alarm, which is activated as soon as the operator gets up from the seat without having engaged the parking brake. In some models, especially those equipped with continuously variable transmission, the vehicle lock is automatically activated when the operator leaves the workstation. Machines with CVT transmission also have an additional level of safety, due to the characteristics of this transmission: it is sufficient to stop the machine (or release the accelerator pedal, depending on the driving mode being used) for the wheels to remain locked even if the tractor is on a slope. This avoids the risk of unintentional forward or backward movement on a slope, which benefits the safety of those working around the vehicle and also motorists, should they be on the road. Other transmission- and electronics-related automatisms with a positive impact on worker safety are the systems that compensate for imbalances on the road, whether caused by an implement being carried on the lift or by centrifugal force when cornering. Premium machines equipped with electronically controlled active suspension are able to compensate for body roll when cornering by increasing the suspension response on the outer wheel. This results in greater stability. On the other hand, to reduce the pitching effect due to a load carried on the three-point linkage, a sway compensation device has been in place for several years now: a true hydraulic shock absorber integrated in the linkage arms that reduces the undulating forces transmitted by the implement, especially if it is heavy and overhanging, to the tractor. We close with two automatic safety systems related to functions that are not common on a tractor and therefore present on a limited number of models and brands. The first relates to four-wheel steering: this function, which greatly increases manoeuvrability in the field, switches off automatically when a certain speed is exceeded (usually 20 km/h) to avoid the risk of losing control of the tractor. Finally, in order to maintain stability on the road, models equipped with the automatic tyre pressure adjustment system have a system that, after reducing tyre pressure in the field to increase flotation, returns it to a safe level when travelling on the road. A further contribution that electronics make to work safety in agriculture.
Additional protections for special activities
The tractor is a multifunctional machine by definition, but there are certain activities that fall far outside the normal routine and for which optional safety systems, specific to those fields of application, are therefore provided. These include first and foremost forestry, for which additional guards are usually fitted on the cab roof, given the real danger of falling logs that this work entails. Windshield and side window screens are also widely used, especially when carrying out work such as chopping logs or the like. Screens on the windscreen but also on the right side for machines intended for municipal work such as cleaning embankments, finally. For these, many manufacturers also offer, on request, the replacement of the front or side glass with polycarbonate panels, which are as transparent as the classic windshield but impervious to stone impacts.
