Late last year New Holland unveiled an unusual double-cutterbar combine header claimed to be capable of upping harvester output by up to 15%. For the past two harvests Warwickshire farm manager Richard Ward has had prototype versions of the new twin-knife Dual Stream concept on evaluation and in his view work rates in United Kingdom crops are increased by more than three times New Holland’s official claim.
“We’ve seen output with our CX6080 go from 23 tonnes an hour to over 35t an hour – in wheat and in rape the difference is even bigger.
“By having one knife effectively just snipping off the ears – or pods – and only that running through the combine while the second cutterbar chops the stubble down to normal height, we’re cutting a huge amount more crop and the grain is coming off drier.
“Every few years combine manufacturers come up with an invention that ups harvesting capacity by a few per cent – maybe up to 10%, possibly even 15%. But in my book, never before has any invention ever increased harvester output as much as the Dual Stream header,” Ward said.
With 15% less wheat straw going through the combine Richard Ward has seen output go from 23t/hour to over 35t/hour.
How has it performed in the field?
This year the CX6080 averaged an output of 37.5t/hour in 10-14t/ha crops of wheat with the 7.65m Dual Stream header set-up so that the front knife was cutting 10cm above the rear one. In contrast, with both knives cutting at normal height capacity dropped to 25t/hour – the same rate usually achieved with the farm’s conventional 6m header.
With the height differential increased to 25cm for oilseed rape there is a far greater reduction in the volume of material passing through the combine with the result that work rates in a crop yielding 3t/ha jumped from 1.7ha/hour with the conventional header to more than 3ha/hour with the double-cutterbar table, an increase of 76%.
What’s different on the combine?
Ward’s CX6080 required an additional maize-header PTO drive to be fitted on the right-hand side of the straw elevator to provide power for the second knife on the Dual Stream header – it’s reckoned to use about 4hp. The hydraulics to raise and lower the knife and roller to get the header on to the trailer for transport were then plumbed into the Varifeed table extension circuit with an electronic diverter valve sending oil in the required direction.
In work, with 15% less straw going into the combine the flow of material through the various threshing and separation elements is very different.
“While walker losses were always the limiting factor for us previously, that’s no longer an issue,” Ward said.
“It’s now the sieves that are under pressure. They have to be set-up to work at maximum capacity so there’s more wind and they’re opened wider – typically 20mm on the top and 15mm on the bottom for wheat.”
The effect on rotary combines could be even greater because with less straw, full use is being made of the separation area and the front-end of the rotor is not overloaded.
How does it handle laid crops?
“Where cereals have gone flat you drop the main cutterbar all the way down to just above the ground and it runs just as a conventional header would,” Ward said.
“Where the tramlines have been run down in desiccated oilseed rape, you tilt the header over so that it picks up the lower pods on the plants pushed over between the wheelings. Because the rear knife can flex and floats on the outer cage rollers it maintains an even cut regardless of the header angle.”
There is also less risk of stones and other debris making their way into the combine and causing damage thanks to the higher cutting height of the primary knife. The secondary digger bucket-derived cutterbar is almost immune from damage because of its irregular knife spacing, which makes it very difficult for stones to jam in it.
“This season I’ve only broken one knife section. And when I’ve checked the stone-trap it’s been completely empty,” Ward said.
“Not only does the blade spacing on the flexible secondary cutterbar stop stones damaging it, it also makes for much more even, peak-free power loading.”
What are the downsides?
Those who bale their straw will see bale counts drop by about 15% – equivalent to the reduction in material passing through the combine. But Ward pointed out that the straw lost – the bottom 10-15cm – is always the wetter, greener material leaving the driest, most absorbent straw for bedding. Therefore less should be needed.
The prototype header has needed a complex trailer with a hydraulic platform to accommodate its extra bits and pieces. According to New Holland, a more conventional trolley will be available for production versions.
When will it go on sale?
Having proved the concept New Holland plans to test the Dual Stream kit on bigger headers up to 12.5m next season. If everything goes to plan it is hoped the new headers will go on sale in the next couple of years.
However, the company is keen to stress the performance achieved in high-yielding crops at Richard Ward’s farm is exceptional and is conservative in its estimates for output, citing increases of about 15%.
Barton Farms and CHR Farming near Moreton-in-Marsh, Warwickshire, United Kingdom
- CHR is a joint venture set-up for machinery and labour sharing between Barton Farms and neighbour Edward Hicks and Sons
- Staff: Richard Ward and Edward Hicks with three full-time employees
- Farmed area – 607ha, cropping 360ha
Dual Stream in a nutshell
- 25-50% increase in output in cereals
- 50-75% increase in output in oilseed rape
- 30% less fuel per tonne of grain – chopping or swathing straw
- 15% fewer bales but driest straw from top portion of crop left in swath
- Few if any foreign objects pass through combine – less stone and debris damage
- To watch New Holland’s Dual Stream header in action on Richard Ward’s UK farm go to www.youtube.com/watch?v=EIl0zVlD4qI.