Tractors – the latest developments to meet the various demands of the future

“Tractors – the latest developments to meet the various demands of the future”! A promising title that will certainly raise high expectations among agricultural machinery and equipment journalists! 

However, the question that arises first of all is what demands will actually be made of tractors? Attention will certainly focus on the demands made by customers. These can be very diverse, especially for manufacturers with global operations. The demands of a tractor made by a customer in a newly industrializing country, who is perhaps taking the first real step from animal traction to a tractor, are likely to be quite different from those made by a professional contractor in Western Europe. Different demands also arise from the different levels of regulation and legislation prevailing around the world, for example as regards exhaust gas emissions. However, “internal” factors must also be taken into account among the tractor manufacturers and sales organizations, such as for instance assembly processes, options for upgrading with accessories, or ease of repairs. 
Today, though, we are only discussing the demands made of high-tech tractors by large farms and contractors in Europe. With the aid of three selected examples of demands, I intend to show you with what technical solutions manufacturers tackle such requirements. 

Traction efficiency 

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At this year’s Agritechnica too, many components and additional options aiming to improve the power transfer of tractors during pulling work have been presented. Examples are for instance the EZ inter-axle ballasting system from John Deere, or the two Vario-Grip Pro and Grip Assistant systems from Fendt. One key element for converting engine power into tractive power is the transmission. With the new VarioDrive transmission for tractors in the 1000 Series, Fendt have once again demonstrated their innovative thrust. This transmission is based on the known Vario concept and continues to exhibit an initially coupled basic structure and an altogether simple composition. A new feature is the use of two summing shafts, each powered by a large-angle hydraulic motor. One shaft drives the rear axle, the other the front axle. The hydraulic connection between the hydraulic pump and the motors permits a hydrostatic longitudinal differential effect, which allows permanent and above all torsion-free all-wheel drive. This is beneficial, for example, when cornering, or in the case of strong tyre compression under heavy axle loads. If strong wheel slip occurs on an axle, the longitudinal differential effect can be barred via a coupling.  The hydraulic motor for the front axle can be uncoupled for road travel. In conjunction with the substantially reduced engine speeds needed to reach the maximum speeds allowed in a country, low fuel consumption rates in road use can be expected. 

Improved unladen weight/payload ratio 

With heavy rear-mounted implements and corresponding front ballasting, tractors quickly reach their payload limits. In the past, some manufacturers have tried to design the bodies of their tractors with frame concepts for higher payloads without increasing the unladen weight (e.g. John Deere with the three-quarter steel frame, or Fendt with the cast half-frame).  For a few years now there has been a trend towards engine oil pans with a pronounced chassis function. By contrast with the conventional block construction design, in which the oil pan and the crankcase assume the supporting function together, in the new solutions this function is allocated primarily to the oil pan. For this purpose it is generally executed as a chassis component with stiffening ribs. Examples on the market to date include the 7R Series from John Deere, or the 800 Series Axions from Claas. New followers of this trend are Case-IH and New Holland with the Optum and T7 HD Series. 

Exhaust emission legislation 

The exhaust emission legislation for nonroad vehicles has led to a massive reduction in emissions over the last 15 years. From the Tier 1 emission standard to the currently valid Tier 4, emissions of nitrogen oxides (NOX) and particulate matter (PM) had to be reduced by 95% each (this applies for the power category 130 – 560 kW). The application of more stringent limit values is already on the horizon. With the Tier 5 standard expected towards 2019, the level of PM emissions is to be lowered again and at the same time an additional boundary level for the particle number (PN) is to be introduced. 
As the test cycles for nonroad and heavy-duty road vehicles are not the same, it is not possible to compare the limit levels for these two vehicle categories on a 1:1 basis. Despite this, it can be established that the exhaust emissions of nonroad vehicles will in future lie at a low level similar to that of the EURO-6 trucks. The engine and exhaust technologies of these two vehicle categories are already very similar today. However one exception here is formed by the particulate filters. The EU legislators had actually wanted to make particulate filters compulsory for nonroad vehicles already with the PM boundary values for Tier 3B and 4 emission standards. Thanks to great progress made within the engines (common-rail injection, multi-hole nozzles etc.), some manufacturers today deliberately dispense with this exhaust after-treatment system. However, with the PN limit levels of the Tier 5 emission standard, closed particulate filter systems are likely to become indispensable in future. According to the present state of the art, it looks as though these systems will increasingly be integrated into the SCR catalytic converters, so that the installation space required will probably not increase further.