Wide Span CTF

What is a wide span system?

The simplest way of describing a wide span system is to imagine a tractor being cut in half from front to back, pushing the two halves apart by anything up to around 10 m and joining them together by a beam (see below). The wheel mountings are redesigned so that they can be steered in the same direction of travel as the original tractor (in addition to being provided with differential speed control) as well as at right angles to this direction to allow the machine to travel lengthways along a road or track.
Considerable work was carried out on the design and commercial development of these machines by the late David Dowler and a glimpse of his genius and firm belief in the system as a practical farmer, is documented in a history drawn together from personal anecdotes, pictures and documents.

Wide Span system

Schematic of wide span vehicle. To run on the road, the wheels are turned through ninety degrees and are then steered conventionally. The vehicle can be built on any scale. (Dowler Engineering, UK)

The most common misconception about wide span systems is that they are only suitable for large, regular-shaped and level fields. Nothing could be further from the truth, unless of course the land is so undulating that a conventional 12 m sprayer cannot be used for example! The main initial constraint for these machines is likely to be associated with their capital cost. Economics studies suggest that within a cereals rotation a minimum farm size of around 900 ha would be required, and that three multi-functional units would be needed to run the operation. If you would like more detailed information about the wide span system under development, send an email to us at info@controlledtrafficfarming.com with "wide span" in the subject line.

What are the additional benefits of wide span?

The benefits revolve around a number of features of wide span – the stability afforded by the wide track, the width which more efficiently creates non-trafficked beds of soil, full width support for implements which reduces their weight, less need to fold implements for transportation and greater flexibility in harvesting operations. In detail these benefits include:

  1. Much less land lost to wheelways compared with tractors trying to do the same thing. This means that an immediate increase in yield of around 8% is likely. The drainage around these wheelways will also be better.
  2. The potential to increase farm profit by between 35 and 60 percent in a cereals rotation.
  3. Use of only half the amount of fuel per tonne of crop stored at the farmstead compared with existing systems.
  4. Automatic field marking. This avoids under- and over-lap of all implement passes, including those carried out on grassland. The figure below shows how the system works in an irregular shaped field.
  5. A reduction in chemical use through more precise and targeted applications.
  6. The creation of a system in which organic farming can be more reliably adopted and sustained and on a wider range of soil and farm types. This is achieved through more amenable soil conditions and greater precision that allows inter-row operations to be carried out more effectively, as indicated below.
  7. Optimisation of the benefits of machine stability (it provides an ideal platform for the rapidly developing DGPS technologies), wheel and crop separation, automatic field marking and new and integrated guidance and control methods to provide millimetre precision in row operations. Such a high degree of precision means that:
    1. crop row and inter-row can be managed separately;
    2. non-selective chemicals may be applied to the inter-row when crops are present;
    3. non-chemical methods of weed control can be undertaken more effectively.
  8. Four wheel drive, four wheel crab and differential steer allow the vehicles and implement systems to be highly controlled, even on side-sloping land. Such flexibility of control also ensures that the vehicles can always be maintained precisely on the wheelways.
  9. The opportunity to completely revise cereal harvesting methods to provide the potential for added crop value, reduced weed seed return and an extended harvesting period.
  10. The ability to cut grass for conservation more quickly but with little additional investment.
  11. Maximising the in-field drying area available for making hay or haylage.
  12. The means by which grass for conservation can be quickly and efficiently removed from the field with little or no damage to the remaining sward.
Wide Span field

Illustration of field set out with a wide span vehicle and examples of turning at the headland. With chemical application booms three times the width of the base vehicle, three headland passes are required. The main body of the field is worked with pirouette turns and short index traverses being made on the centre of the three headlands.

Are wide span systems available?

At the moment there are no fully developed commercial wide span systems available, but BioVelop of Sweden and T.E.C. Technology in the UK have been working in cooperation to gradually progress the design and system development. Refurbished Israeli machines built by Ashot Ashkelon in the early 1980s are available to order. These have a 235 hp engine, span 5.8 m and have an underbeam clearance of around 2 m (see below). (contact James Barbour for more information).
There is also a customised wide track design by John Foxwell for CTF on small farms, details of which can be found here

A shift to wide span is a dramatic change for farming and will not come about by normally accepted methods. The existing industry has to be convinced that it is both practical and economically viable before it will be persuaded to invest at the significant level required. This fact was recognised and an "initiative" was formulated to fund development of a full scale demonstration programme involving six of the European Union Member States. Funding for the Wide Span Initiative (WISE) was sought from non-specific sources and sponsors who have an interest in improving the long term economics and sustainability of farming, and particularly as they relate to soil health and environmental issues. Although this initiative has not been successful so far, the partners remain committed to seeking support. If you wish to find out more about this initiative please contact us at info@controlledtrafficfarming.com mentioning WISE in the subject line. You can also find out more about the development of these machines from http://www.TECTechnology.co.uk

Wide span case study

A wide span case study from a farm in Bedfordshire, UK, is now available on this site. The Israeli "Field Power Unit" (FPU) was first introduced in 1996 and its integration is now almost complete. The image below shows the machine direct drilling winter barley in October 2003.

Direct Drilling