The Lighting System Evolution
Modern lighting elements installed on tractors and self-propelled implements make agricultural work easy and safe even in darkness
Agricultural activity typically involves intensive work peaks, for which the regular daylight is often not enough. Therefore, it is necessary also to make use of the evening, and sometimes night hours, especially when it comes to using the machinery. Artificial lighting has contributed to extending the working time, thus further improving productivity.
However, the agricultural machinery activity is made up of alternating field and transfer phases, which involve different lighting requirements. This results in substantially different lighting systems: if the necessary elements for the road are very similar to those adopted in the automotive sector, in the field, it is often required to upgrade and orient the headlights so as to shed light on the entire area around the tractor-machinery site.
Street lighting
As with other vehicles, in order to ensure the safe use of roads open to traffic, agricultural vehicles (both tractors and other machinery intended for circulation) must also be equipped with a series of lights for visual signaling, which identify the overall dimensions, the direction of travel and any maneuvers to be carried out.
Specifically, in order to ensure driving safety and visibility of the vehicle, the Highway Code provides for the fitting of depth headlamps, dipped-beam headlamps, fog lamps, reversing lamps, direction indicators, position, stop, stop, clearance and emergency lamps, etc.
Recently, and especially on the most powerful tractors, headlamps are distinguished by their use during the day or night, being different in light intensity, position, and beam orientation. For a rationalization in construction, assembly, and maintenance, all headlights and projectors are often grouped in the so-called "optical groups", complete with appropriate reflective screens that concentrate and orient the different light beams.
Field lighting
When fieldwork is performed in dark conditions, more complete lighting is required than is necessary on the road. In fact, when circulating, headlights have a higher trim to obtain a greater depth of field and thus facilitate adequate visibility at a distance of several tens of meters. However, the light beam is only directed in the direction of travel so that the driver's gaze is focused on the area of interest.
Conversely, the light beam required for working in the field is typically characterized by a lower inclination to better concentrate the light intensity both on the tractor's transit area, but above all, also on the working area of the machinery connected to it. Often several optional "packages" are provided for this purpose, consisting of adjustable headlights: in fact, in addition to the front lights, rear lights can also be installed on the tractor in order to make the lift and PTO area clearly visible, and sidelights, if required for the best visibility of the equipment.
To further improve the situation, together with the lights available on the tractor, headlights can also be installed on the operating machine to facilitate the operator's control over the work of the equipment, such as a plow or a seed drill.
If the site is more complex, with the presence also of a self-propelled machine, such as a combine harvester and a trailer for the temporary storage of the grain during harvesting, the complex of lights of all vehicles can illuminate almost all the area involved in the activity.
Additional lights
Operator safety and comfort are paramount, especially when working in low visibility conditions. It becomes essential not only to have a clear view of the outside but also when entering and exiting the driver's seat and driving the vehicle, i.e. to ensure correct and unambiguous recognition of the numerous machine controls. Therefore, tractors are increasingly equipped with lights in the cab, as well as indicator lights and backlit buttons. In particular, correct lighting in the driver's seat results in a higher attention threshold, less eye fatigue, and more precise and fine control of the commands. The backlighting of lights, switches, and pushbuttons is now adjustable and, in some cases, is even automatically controlled according to the ambient brightness.
Given the completeness (and sometimes the complexity) of the lighting group, a specific integrated panel is installed on the most recent models so that at a "glance," each headlight, headlamp, or other lighting element is recognizable and easily activated by the driver.
The more accessorized models can also be equipped with headlights projecting the light beam onto the access ladder, which, like the lights in the cab, are kept in operation for some time even after the engine has been turned off, in order to make it easier to get out of the vehicle (such as Fendt's “Coming home”). An additional optional extra is the package of lights pointing at the tanks, diesel, and AdBlue, to promote visibility during refueling in low light conditions.
From incandescent bulb to LEDs
The first bulbs on motor vehicles, as well as on agricultural vehicles, were incandescent filament bulbs. As known, these elements are relatively cheap, usually of limited luminous intensity, with a "warm" shade of color and useful life of about 1000 hours, now in disuse.
Technical progress has then introduced halogen lamps or incandescent elements, where the tungsten filament is housed in a sealed quartz bulb containing a halogen element (iodine or bromine).
The filament warming leads to the sublimation of tungsten, which, combined with the halogen element, generates tungsten halide. When the lamp is turned off, the tungsten is repositioned on the filament to increase its life. Since the 90s of the last century, xenon lamps have spread first and then LED lamps.
Xenon models have a high illuminating power, about three times higher than halogen models, emitting a blue-white light beam with clear lines. These elements have a rather high cost, are widespread on the market as the top of the range, even for their useful life, which is much longer than halogens.
LED lamps, however, have recently overtaken the field, mainly due to their low maintenance and extremely long life, up to 20 times longer than xenon headlights. In addition to the high intensity, LED lights are characterized by the spectrum of radiation emitted, similar to solar radiation.
Furthermore, the energy consumption is optimized, thanks to low heat production, a "spurious" effect considerably present in all other types of lamps. However, LED lights have other advantages: they have high resistance to vibrations and shocks because they have no moving or flexible parts; they are compact and usually point-shaped so that they can be combined with variously shaped groups, thus defining the size and direction of the luminous flux at will, also through the matching with special reflective screens.
If adopted in the so-called "optical groups" of motor vehicles, their cost is still relatively high compared to halogen lamps. Still, it is easy to foresee that their progressive diffusion will soon fill this gap.
The headlamps inclination
For fieldwork, the additional lights can be fixed, usually installed in front and behind the cab top's height, and/or can be swiveled and placed sideways to light the machine's working area fully. The adjustable headlamps make it easy to change the lighted area according to operational needs by varying their inclination.
Of course, this adjustment also impacts the intensity of the light beam: in order to optimize the visibility of the area of interest, it is, therefore, useful to apply more headlamps, performing a complementary action between them.
Moreover, it may be necessary to require a deeper view of the front. Therefore the application of adjustable headlights on the front also solves the problem. This is also the case at the rear when visibility needs to be maximized on the operating machine.
Also in a retrofit kit
Since they must necessarily be installed in an open position to project the light beam without interference, headlights, headlamps, and other lighting elements are often subject to damage while the tractor is in motion because of impacts, shocks, and interference of external obstacles.
For this reason, while on recent models’ optical groups are installed that fit harmoniously into the machinery's silhouette, on older vehicles, lights are almost always in relief, clearly risking being damaged. For some time, the market has been offering lighting kits, approved following the Highway Code requirements, complete if necessary, with the electrical system supplied.
The range for work lights is even wider as the spread of the LED type has made it possible, thanks to the high flexibility of construction, to expand the choice of size and shape of the headlights significantly, thus adapted to the retrofit application in the most appropriate areas of the vehicle.
