Field testing of combine harvester John Deere T560i powered by rapeseed oil.

The idea of operating a combine harvester on vegetable oil was born on the fringes of the VDI Landtechnik conference which took place from November 20th to 21^st, 2018 in Leinfelden-Echterdingen near Stuttgart. Dr. Axel Kunz, who has been responsible for rapeseed-oil-powered tractors with the John Deere plant in Mannheim for many years, quickly developed the idea into a project together with Dr. Martin Büermann, Engineering Manager John Deere Werke Zweibrücken: It could be called a coincidence, but at the same time a suitable machine - a T560i - was available in Zweibrücken and had all the prerequisites to serve as a test vehicle for using vegetable oil.

In February 2019, Dr. Kunz and his team in Mannheim worked out a concept for converting the combine harvester, based on preliminary developments on Mannheim tractors and the experience gained from the Rapster with a similar 9.0-liter engine. After a cross-check by the employees in Zweibrücken, the design changes were then made a reality at the end of May 2019: the conversion itself included the implementation of a low-pressure fuel system adapted to the requirements of vegetable oil with two additional feed pumps between the tank and the fuel pre-filter, larger line cross-sections with several size-adapted non-return and pressure relief valves instead of simple throttles and orifices.

The mechanical alteration, which was completed within one single day, was followed only by the modification of the rapeseed oil software by the John Deere European Technology Innovation Center (ETIC) in Kaiserslautern and the associated performance control. The measurements on the test bench showed that the operation on rapeseed oil at a nominal speed of 2,200 rpm produces 4% more power than diesel operation, but also results in 12% higher consumption, due to the lower energy density of the biofuel. But how reliably would the combine harvester with the eco-friendly diesel version ultimately run?

Fortunately, Dr. Kunz and his team didn’t have to wait too long: from early June there was already a lot to do for the machine in the German-French border area. Under the supervision of Harald Freyer, head of testing in Zweibrücken, and his team, in particular Kai Kunkler, the John Deere T560i was in operation for 292 hours until September 27th, mainly for harvesting wheat, oats, rye and rape. The T560i also completed the subsequent operation in corn with the corn bit instead of the chopper almost brilliantly over a further 150 hours of operation.

In summary, it was found that the operation of the machine was absolutely trouble-free and the driving and working experience was not affected negatively. In addition, no error codes, so-called Diagnostic Trouble Codes, were found on the fuel system, and there were no component failures. However, the cold start performance of the John Deere T560i combine harvester shows capacity of improvement, which could be achieved by revising the software. In addition, the supply of rapeseed oil requires additional logistical effort, since a longer filling time must be planned for when refueling with a standard fuel pump due to the high viscosity.

However, if reliable signals were finally sent out by European and national governments in order to promote the use of plant oil fuels in the agricultural sector, the engineering companies could be much more motivated to further develop already existing concepts. Not least because a significant reduction of greenhouse gas emissions is at the same time demanded of the farmers