How to avoid combine chaos

Reducing tyre pressure should be the first step in keeping heavy machinery afloat in wet conditions, writes

AFTER a great start to the harvest some mixed weather in the last few weeks has seen conditions grow more difficult in wetter parts of the country.

This throws up the problem of ground damage, and combines — being such weighty machines — can cause havoc when conditions deteriorate.

Is it worth doing anything about it? As can be seen from Table 1, your options 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 but some will look longer term and be willing to invest in flotation improvement changes to the machine.

The best “value for money” change you can make to help yourself in soft ground conditions is to reduce tyre pressures.

While ever increasing combine weights actually cause the soil compaction, tyres play a critical role because they determine how that weight is distributed.

It’s the same principle that sees Eskimos wearing snow shoes in snow. Large tyres, or indeed more tyres (for example fitting duals), will spread the weight over a bigger area, and therefore reduce a machine’s ground pressure.

I’ve been to countless tyre manufacturer events and the key message I hear for Irish farmers is always the same; that we are perennial offenders when it comes to over inflating our tyres.

The experts insist we should be operating our heavy machinery (like harvesters) on tyre pressures from as low as 5psi (.34 bar) to maximum 14psi (1 bar).

In reality, many contractors continue to operate at pressures far greater than this (see graph) because there are road going benefits, chiefly lower wear rates. Growers need to make it known to their contractor if they want lower ground pressures in the field.

As for the adjustments that cost money, the most common option is fitting dual wheels to the front of the combine.

Cavan-based wheel and tyre specialists, AgriGear Ltd, say a pair of duals typically costs around €2,400.

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. An option some go for that can also be effective is fitting 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.

Going the whole hog and retrofitting 4WD to the combine has proved a popular move over the last five summers for many.

Retrofitting 4WD typically costs about €15,000 but the move adds value to the combine and it only takes about 12 hours to fit. The 4WD system can also be removed and fitted to a new combine if/when the owner decides to upgrade.

Tracks

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 in terms of flotation.

Most of the main combine manufacturers now offer tracks including Claas and New Holland.

With New Holland’s SmartTrack system you have 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 obvious 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 to all models.

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Lift the header to leave some straw for traction. This will also avoid broken sections and fingers Ditch the super singles on grain trailers, they are lethal for compaction and rutting Only start the unloading auger on the combine if you are sure you can empty the grain tank in full. Stopping an auger in the middle of unloading and then starting it again places huge pressure on the flights as the auger is full of damp grain. Unload at the headlands or near field exits to minimise the tractor/trailer’s chances of getting buried. A straw chopper should be removed if not being used because it adds weight (ground pressure) to

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the rear of a combine. A modern combine with a full grain and fuel tank can weight in excess of 24 tonnes.

To keep compaction damage to a minimum, accept the slower work rates that come hand in hand with only half filling combine grain tanks and trailers. Remember, if it keeps you moving you are still winning the war against the weather.

If you do go down, use bungee ropes, not chains, for pulling the combine out. The pressure comes on a bungee rope in gradual phases — as opposed to a sudden jolt you get with chains. It is best to hook up somewhere on the front axle and, bringing the pressure on as gently as possible, pull the machine out backwards.

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