Increasing focus on fuel consumption by tractor manufacturers

Just how good are modern tractor engines at burning diesel to generate energy? Well, very good, judging by the claims flowing from manufacturers keen to justify the hike in prices new emissions limits has brought about.

The latest prices shown in the Power Farming website database, a unique online resource that enables tractor specifications and list prices to be easily compared, are not all the result of new engines, it must be said.

In most cases, manufacturers have added or upgraded features to increase the appeal of their tractors and some have developed all-new models to coincide with the latest round of emissions-compliant engine introductions.

But the research, development and technology required to enable big diesel engines to meet the exacting requirements of Euro Stage 3B/US Tier 4 Interim rules has cost an awful lot of money, which has to be passed on to buyers.

Happily, having to throw a lot of advanced electronics, specialist filtration systems and exhaust after-treatment technologies at the problem has brought about an improvement in combustion efficiency. The resulting potential savings in fuel use may not go all the way to offsetting the higher purchase price of the tractors, but it certainly helps.

Case IH

Case IH illustrated the point at the launch of its “EfficientPower” Steiger, Magnum and Puma models by rigging up two equivalent Puma models with fuel flow meters and coupling them to dynamometers.

The live comparison between a Puma CVX 225 with Stage 3A engine and a Puma CVX 230 with SCR-equipped Stage 3B compliant engine consistently showed an average 10% fuel saving across different loads and power outputs.

With almost 20hp more peak output and higher levels of torque, the newer engine should also be more productive in the field.

There is the cost of AdBlue urea solution to take into account, but Case IH’s headline message was clear: For every £1 spent on AdBlue, operators will save up to £7 through lower fuel costs.

New Holland

A bit more flesh was put on the bones of that argument by a similar demonstration staged at last year’s Tillage-Live event by New Holland.This compared a 212/241hp T7050 and a 218/250hp T7.250 put through a load cycle on dynamometers and with the fuel consumed shown in highly visible manner by the two clear containers positioned between them.

Calculations based on the figures compiled on the day suggest operators switching from the older tractor to the newer one could see their fuel bills cut by more £3,500. The measurements taken over just a short period showed differences of six litres an hour or £35.17 a day when taking the cost of AdBlue into account at 35p/litre.

One reason for this improvement in efficiency is that the combustion process has largely been liberated from trying to generate power and torque while constrained by emissions requirements.

With the selective catalytic reduction system used on New Holland tractors dealing with nitrous oxides in the exhaust gases, combustion can be tuned to the optimum.

When manufacturers had to switch from Tier 2 to Tier 3 emissions compliance, drivers complained of dull engine response; the tractors did not have the same get-up-and-go. This time, things are different – some engineers describe it as going back to a Stage 1-spec engine.

Further efficiency gains have been won by optimising cooling air flow and taking advantage of the reduced cooling demands of an engine using SCR rather than exhaust gas recirculation (EGR) – the technology relied upon previously. The latter alone has cut the power taken by the cooling fan by 4-5hp, say New Holland engineers.

Their tests also confirm that the latest-spec engines are livelier, resulting in real-world performance gains. In a heavy trailer-towing test designed to compare transient response – the way a diesel engine responds to the accelerator pedal and builds revs – the newer engine moved from 850rpm to 2,000rpm up to 16% faster than its predecessor and completed a hill-climb challenge 20% faster.Independent tests have also highlighted gains. In a DLG PowerMix comparison, which combines the results of individual pulling and pto tests, operating a pto-driven trailed implement and placing continuous demand on the hydraulics system, the T7 achieved a 14% improvement in work rate overall and a 10% average gain in fuel economy.

It is also important to recognise the achievements of engine and tractor engineers in meeting the exacting emissions rules – it takes 100 of the latest tractors to produce the same quantity of pollutants as just one tractor a decade ago.

John Deere

Manufacturers have also turned to other recognised test organisations to illustrate the new fuel frugality of their machines. In North America, the Nebraska Tractor Test Laboratory (NTTL) is the recognised authority.

So it is little wonder that John Deere publicised the results when one of its 8R Series tractors, equipped with cooled exhaust gas recirculation (EGR) and other technologies to meet Tier 4i emissions, broke fuel efficiency records for large rigid frame four-wheel drive tractors.

It scored leading fuel economy figures in four of the five tests that are considered to most closely represent how these tractors are used in the field – rated engine speed pto; maximum drawbar power; 75% of pull at maximum power; and 75% of pull at reduced engine speed.

First, a 320/355hp 8320R (since then superseded by an updated model) broke the record for the rated engine speed pto test with a specific consumption figure of 228g/kWh. It displaced one of its predecessors, the John Deere 8430, but was soon itself displaced when a 295/330hp 8295R set the bar higher still with a figure of 225g/kWh in the same pto test.

The 8295R also set NTTL records as the most fuel efficient tractor in its class in most drawbar tests, and came within 5g/kWh of the best figure achieved for the test at 75% of pull at maximum power.

The results for other 8R models are similar, John Deere points out.Back in Europe, Case IH has trumpeted the results of DLG PowerMix tests when several of its FPT-engined Puma CVX EfficientPower models topped the results.

The 177/203hp Puma 160, 234/260hp 215 and 249/269hp 230 produced best-in-class specific fuel consumption figures of 259g/kWh, 261g/kWh and 268g/kWh, respectively; reportedly the best achieved worldwide in this power bracket.

Low specific fuel consumption figures characterise the tractors across all operating conditions, say Case IH engineers, from heavy draught work and hydraulic applications to demanding tasks with pto-driven equipment, as reflecting by the DLG PowerMix test regime.

In some cases, they add, the Puma tractors consumed up to 14g/kWh less diesel than their nearest competitors.

Fendt

Since then, a 276hp Fendt 828 Vario had in an impressive performance, setting a new DLG PowerMix record of 245g/kWh – a 6.5% advantage over the next-best tractor.

On that basis, Fendt engineers calculate that with a diesel price of 69-70p/litre, the most powerful of the new Fendt 800 Vario series tractors, which are powered by 6.06-litre Deutz engines equipped with SCR emissions technology, offers a £3.70/hr saving in fuel over its nearest rival.

That calculation takes into account the cost of AdBlue urea solution for the SCR system, which was also recorded in the test.

Extending the calculation further suggests a Fendt 828 working 1,000 hours a year will use £3,700-worth less diesel over 12 months or £11,100-worth over a three-year period.

And that is in comparison with the next-best; with a specific consumption figure of 245g/kWh, the tractor is over 18% more fuel efficient than the 301g/kWh average recorded at the DLG test centre.

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