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Anno 2021 Numero 1 - 2

Technology
January - February 2021

Tractors designed for mountain farming

Tractors for mountain farms must be exceptionally reliable, efficient, and safe. There is high-tech machinery specifically designed to carry out modern and profitable agriculture in mountain areas on the market

Orographically speaking, Italy is characterized by a prevalently hilly terrain (41.6% of the total surface area, where 38.9% of the population lives), followed by mountainous territory (35.2%, with 12.2% of the population) and finally flat land (23.2%, with 48.9% of the population).

The Agricultural Land Used is evenly divided between municipalities considered mountainous and non-mountainous. According to the latest Agricultural Census (6th Census, ISTAT, 2010), mountain farms have a larger average size in terms of ALU, and crops are mainly extensive and with low added value, in respect of the surface unit. Since the land is often limited, the larger surface area does not compensate for the lower productivity, therefore the average production values of mountain farms are almost halved compared to the hill and plain ones.

Clearly, this does not prevent the production in the mountains of typical and extraordinary agro-alimentary products: from dairy products to minor cereals, officinal herbs, horticultural products, but also those zootechnical breedings (goats and sheep in particular) that may find a new revival in mountain areas, thanks to the availability of excellent quality fodder and the enhancement of unique knowledge, which would otherwise be lost. All this helps to limit the mountain depopulation, safeguarding areas of Italy of outstanding landscape attractiveness.

In order to be able to practice income-generating agriculture in such a complicated environment, with irregularly shaped plots of land, steep slopes and critical climatic conditions requiring a higher level of promptness of intervention than in lowland agriculture, it is necessary to carefully define the criteria for choosing the agricultural machinery to be used, with particular regard to tractors.

When choosing a tractor, consideration must be given to operating efficiency and safety, adequate working capacity and, possibly, useful multi-utility features. This last objective is probably the most difficult to achieve: The concept of a "multi-utility" tractor in the mountains is difficult to apply: The standard 4WD tractor with average power, which on a plain farm can carry out almost all farm operations, with the only limitation being the size of the equipment that can be coupled, has several application limits in the mountains.

An example of this would be primary tillage: On steep terrain, the conventional wheeled tractor is extremely limited, particularly in terms of stability and adherence, so the most suitable vehicle in this situation would be a crawler with steel tracks. In fact, it is no coincidence that Italy is the European country with the highest percentage of crawlers in the circulating fleet.

By its very nature, a crawler machine generates enough tractive force to plow with trailed plows while at the same time ensuring exceptional stability, thanks to its very low center of gravity and wide track width. However, due to its limited maximum speed (max. 15 km/h), steel crawlers are not suitable for other work types, such as haymaking (also because of the risk of damaging the turf when turning).

Similarly, they are highly unsuitable for transport and, more generally, for road transfers, which, among other things, require the compulsory application of special track pads. Therefore, it is necessary to have one or more wheeled tractors on the farm to carry out all other cultivation operations. This paper aims to present wheeled tractors specifically designed and manufactured to be used in mountainous areas.

 

Key features

In general, a wheeled tractor for mountain use should be featured with: 4-wheel drive, both to maximize tractive force and to take advantage of an efficient engine brake when going downhill; disc brakes on all four wheels, always operable regardless of whether the front-wheel drive is engaged or not; a low center of gravity; wide track width (subject to compliance with road limits), coupled with appropriate tires or, alternatively, with the possibility of mounting twin wheels; high engine torque reserve to easily overcome any increase in gradient without having to shift gears. In fact, in the event of an uphill stop because of insufficient engine torque, the restart becomes a challenge both in mechanical terms (the stress to which the transmission is subjected is enormous) and in terms of safety for the operator if the vehicle loses grip.

 

Important equipment

They can be: the synchronized power take-off, for coupling with powered axle trailers; the front lift; the reversible guide is very useful for better managing the weight distribution between the front and rear axle after the coupling with the operating machine. Moreover, in some operations (such as mowing forage), the reversible guide allows excellent visibility on the cutting device, allowing to finish at best and safely the border areas between field and undergrowth.

Although it is not difficult to find conventional 4WD tractors with most of the features mentioned above on mountain farms, several Italian and foreign manufacturers are increasingly committed to developing tractor models designed explicitly for Alpine and Apennine farms, also in response to the needs expressed by users at dedicated agricultural events, whose importance is growing year after year.

A short review

Antonio Carraro of Campodarsego (PD) is one of the Italian manufacturers offering mountain machines, with the wide-track reversible isodiametric models of the TTR range. The engine power range is between 70 and 98 Hp; the synchronized transmission can be 16+16 or 32+32 gears with Hi-Lo. It is possible to choose between an air-conditioned cab and a protection frame. All models have a front lift with Uniflex hydraulic suspension, which allows transferring part of the operating machine's weight directly onto the wheels of the tractor, thus improving grip and stability. Another interesting technical feature is the Actio chassis, which, through a central joint, allows the front axle to oscillate longitudinally by up to 15°, so as to follow the profile of the ground, maintaining a high ground contact in all conditions, to the benefit of stability and traction.

BM Tractors of Zocca (MO) produces wide-track reversible isodiametric tractors, with power ranging from 130 to 180 Hp and independent 4-wheel steering in different configurations (front only, rear only, front and rear, crab steer). The transmission is hydrostatic with electronic control. It is possible to have the front lift and the cab, with excellent visibility and soundproof, is suspended on pneumatic shock absorbers for better comfort of the operator. The rear lift features a nitrogen shock absorber for better "flotation" of the coupled operating machine.

Beyond national borders, the Austrian company Reform-Werke of Welk has been in this market segment for some time now, offering the Metrac, a machine with a wide track and low center of gravity, specialized for haymaking. Available powers range from 49 to 91 Hp, the transmission can be hydrostatic or mechanical (8+8 or 12+12 gears), and the cab is equipped with heating and air conditioning. In this case, too, the tractor's architecture enables it to be coupled front and rear with the implements, thus enhancing its multifunctionality. It is possible to adjust the ground load of the implements carried through dedicated hydraulic cylinders, displacing a good part of their mass on the front wheels. Finally, an anti-oscillation system reduces the vibrations caused by the mounted implements while driving.

Headquartered in Küssnacht, Switzerland, Rigitrac produces four tractor models, both conventional and isodiametric wheeled. Diesel engines range in power from 75 to 150 Hp, but a 54-Hp electric model, powered by lithium-ion batteries, is also offered in the catalog. Steering is independent on the four wheels, and a joint is mounted at the center of the tractor body to allow an oscillation in the vertical plane of the front axle up to 22°. This enables the tractor to cope well with uneven terrain, improving stability and traction. The transmission is hydrostatic and continuously variable, the front axle is suspended with the possibility of automatic leveling, and the cab is air-conditioned. It is completed by front and rear lifts.

The above-described models, which certainly do not exhaust the market panorama, are all characterized by a very high technological content, which optimizes performance and ensures very high safety levels for operators. Therefore, it is now possible to have reliable and efficient machines even in the mountains, which is an essential condition to operate modern and profitable agriculture.

by Aldo Calcante

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