Why farmers shouldn't cut corners on tyre costs
Tyre choice and running gear is becoming a bigger priority for contractors as combine harvesters grow in size, weight and power
Mixed weather in the last few weeks has seen harvest conditions get a little tricky in some parts of the country.
This throws up the problem of ground damage as heavy combines can cause havoc when conditions deteriorate.
Your options for improving combine flotation will vary depending on how much (if anything) you are willing to spend. The majority of farmers and contractors will want to spend as little as possible.
The best value-for-money change you can make to help yourself in soft ground conditions is to reduce tyre pressure.
Tyres play a critical role because they determine how a machine's weight is distributed. Large tyres with lower ground pressure, or indeed more tyres (for example fitting duals), will spread the weight over a bigger area, and therefore reduce a machine's ground pressure.
Gordon Brookes, Customer Engineering Support Manager at Michelin, believes running gear and tyre choice is increasing in importance as harvesters grow in size, weight and power.
He also warns that most machinery dealers don't focus heavily enough on tyres when securing an order, so farmers should seek expert advice from their tyre manufacturer or dealer.
Offering advice as the 2019 harvest season kicks off, he says: "The rear axle is the smallest tyre, so that's always going to be where the damage is most likely to be done.
"Farmers naturally look at the front because that is where everything is going on, whilst often forgetting that when the combine is full, the back end is extremely heavy despite being on a very small tyre.
"When travelling without the header mounted, there is no weight transfer from the rear axle, so the rear tyre loads can be very high. Sometimes, you'll even see the rear axle specified on the same tyres you'd fit on a loader, so shifting some of the focus from front to rear would pay huge dividends so far as soil compaction is concerned."
While four-wheel drive harvesters require lugged tyres on the rear, Brookes says farmers can access a much wider range of fitments if they're using a two-wheel drive machine.
"If minimising compaction is your number one issue, then you can select a flotation tyre like the Michelin CargoXBib. This tyre is designed to spread the weight of laden agricultural trailers, so it's always going to be better at reducing compaction than a smaller fitment."
Another area where Brookes (below) says farmers should focus their attention is tyre pressures.
"Nearly all machinery manufacturers leave tyres at the fitting pressure - normally around 35psi - and then the dealer is supposed to amend the pressure if it is appropriate prior to delivery.
"But only a small percentage do - invariably as they don't know how the machine will be used," he says. "If the farmer is combining linseed, for example, it has a different density to wheat or barley and the tyre pressure is dependent on what you are harvesting."
Michelin is happy to provide bespoke tyre pressure recommendations if a harvester is on Michelin tyres. Brookes says that setting up new harvester tyres correctly is essential.
"Bear in mind that a typical combine might have four different headers and they will all be different weights. The tyre pressure will be different in each scenario," he says.
Other options to boost flotation
As alluded to already, some may opt to fit bigger tyres and/or rims to the rear of the combine to reduce rolling resistance and give more momentum.
At around €1,200, this is a cheaper option than duals on the front. For those thinking of making more significant changes to improve flotation at the front of the combine, a common option is fitting dual wheels.
Cavan-based wheel and tyre specialists, AgriGear Ltd, report that a pair of duals typically costs between €2,400 to €2,600.
While effective, duals need to be removed when entering and leaving many fields because they add extra width to the combine, and some operators won't have the manpower to do this.
Sometimes duals can be bought second hand and this can reduce the cost significantly.
Going the whole hog and retrofitting 4WD to the combine has been done for many operators in the past. Retrofitting 4WD is not cheap - it typically costs about €15,000-€17,,000 but the move really adds value to a combine and it only takes about 12 hours to fit.
The 4WD system can also be removed and fitted to a new combine if and when the owner decides to upgrade.
Finally, a very expensive but effective route is having tracks fitted to the combine. Fitting tracks is a big job and typically costs from €40,000 upwards, depending on the model. Tracks offer the same ability as 4wd of climbing steep inclines and getting combines out of difficult conditions, but they excel further in terms of flotation.
Most of the main combine manufacturers now offer tracks, including Claas and New Holland.
They allow up to a 100pc increase in ground contact area compared to when using tyres, and a huge reduction in ground pressure as a result - just 1 bar pressure with tracks versus around 1.6 bar with even a really good, wide 1,050mm tyre. Users report very good flotation.
The downsides include cost and there can be grubbing issues at sharp headland turns in the field. Also, tracks wear about four times faster than tyres do on the road, and the option isn't available on all makes of combine just yet.
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