Wednesday 28 September 2016

Fine-tuning the combine harvester

A thorough maintenance check now can avoid costly and time-consuming combine breakdowns during the harvest season

Derek Casey

Published 08/07/2015 | 02:30

As the harvest progresses over the next few weeks, regular maintenance checks are the key for keeping belts and pulleys on the move.
As the harvest progresses over the next few weeks, regular maintenance checks are the key for keeping belts and pulleys on the move.
The wobble box needs close attention and is one of the hardest working parts on the combine
Combine belts
Combine knives

Our warm summer weather has accelerated the ripening of crops with the result that combines will be turning into the first fields of winter barley in southern counties over the next week.

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It is important to remember that warm temperatures can throw up a few unusual hazards for combines. Engines become hotter and risk overheating, while the fire hazard increases greatly as dust builds up in and around the hardest-working parts.

Running gear is another key concern with tyre pressures playing a major role in how well your machine performs. As the harvest progresses over the next few weeks, the following tips should help keep belts and pulleys on the move.

Check your tyres

"Time, weather and crop constraints make it essential that machinery is ready for use. Leaving checks until the last minute can result in unexpected machine downtime," according to Michelin's technical manager, Gordon Brookes.

He says that during previous harvests tyres may have suffered accidental damage, leaving them with bulges, cuts or tears. Checking the tread area and sidewalls right down to the wheel trim helps detect problems as soon as possible

Long periods of inactivity can leave tyres with a 'flat spot' due to one section of the casing being deflected, creating massive vibrations on the road.

To combat this, mark the affected area of the tyres, move the combine into direct sunlight with other sections of the tyres deflected.

If possible, inflate the tyres above your standard operating pressure for a couple of hours, while ensuring the manufacturer's maximum inflation pressure is not exceeded. Warming the tyres in the sunlight will prompt the casing to return to its normal shape.

Other issues to consider are maximum cyclic load in the field and whether the combine will be used on side slopes or intensively on the roads.

If you need new tyres, or a new machine, take tyre choice seriously. Tyre choice can make the difference between a good harvest and a great one.

Is your combine too wide for the road or gateways, and would a narrower tyre speed up the harvesting process?

If so, there are now tyres for combines that are narrower but have a greater contact with the ground. For example, a Michelin 900/60 R32 conventional tyre assembly could be replaced by a Michelin IF 800/70 R32 assembly, giving a 15pc larger footprint while making the combine 200mm narrower.

Rear tyres can also impact the efficiency of the combine, particularly in wet weather, but are more commonly neglected. Rear tyres should be operated appropriately in line with manufacturer recommendations. It's therefore important to allocate the same time specifying rear tyres as you would the front set.

Keep a regular routine

Once the harvest starts the aim should be a regular combine maintenance routine. Carrying out this well-rehearsed routine in the morning rather than at night, with the exception of cleaning off the chaff and dust.

Some operators argue that for certain jobs, for example greasing, the grease will travel more effectively in around warm bearings than cold ones. This is a fair point, but the main thing to remember is to get into the habit of doing all the vital checks at a given time in the day to help you remember them all.

Essential daily checks

The most important steps in maintenance are greasing all the nipples, checking the air filters for cleanliness and adjusting the chains for tightness.

Every morning, you should grease all 10-hour nipples. A good habit to get into is doing a couple of related jobs in one sequence.

For example, when filling the machines with fuel, check both engine and hydraulic oil levels, and then check the radiators to see if they have sufficient water - critical during these long, hot days.

Stone traps do not necessarily need to be checked every day if the crop is generally clean, but in modern combines access to the stone trap is simple so it may be worth taking the 10 seconds needed to have a look.

The header is obviously a very important part of the combine and contains a lot of moving parts.

Every day you need to look for any serious damage to the knives, skids or fingers. The wobble box should be getting a full inspection in a pre-season maintenance programme at your local dealer or in your own garage.

A wobble box working for around 200 hours per season will generally last for anything from eight to 10 years depending on the operator.

Other checks

Every two days you should check the air filters for cleanliness, grease any 25-hour nipples or 50-hour nipples, and check chain tensions - especially the feeder house chains.

On some machines the feeder house chains sit on pieces of timber that look similar to roof slats. Over time, the chains can wear into these timbers with the result being the chains can slacken.

As well as monitoring the chains for slackness, the timbers themselves will need to be replaced periodically so keep a close eye on them. Watch out for broken or bent chain reels on the intake as well.

Once-a-week checks include emptying the stone traps when combining trouble-free crops. Other common parts that tend to wear out over time include bearings, chains, belts, sprockets, sickle sections and injector lines. A good visual inspection is key.

Check belt tensions for wear and tear. How do you know if a belt is slack?

First of all, switch off the engine if you are doing any hand inspections. You should only be able to get half a twist by hand on a belt that is properly tensioned.

If you can twist a belt all the way around, 360 degrees, it needs to be tensioned to prevent excessive wearing.

Tools and spares

A lot of contractors these days have service vans in which they carry all their tools and spare parts. A number of grease guns, a wrench set and a socket set are three essentials.

A generator/welder combination is also useful to patch up small problems.

Parts that should be kept in stock include a full set of belts for the combine; a belt-tightener pulley; connector links, half links and chains; sickle sections and guards for the cutterbar; drive chains for the heads; and fingers for the header auger.

Engine and hydraulic oil, assorted bearings, bolts and nuts, and a supply of welding rods are useful too.

Rat trouble

A modern combine can still be brought to its knees by a rat.

Dealers tell horror stories each year about contractors spending €300,000 on a new combine only to not even bother cleaning it thoroughly when the harvest finishes.

The trouble is that it will be sitting in a shed over winter with plenty of grains waiting to be devoured by rats. When this grain is eaten the rats will then start eating wires.

The moral of the story is that when the harvest is done give the combine a good cleaning with an air compressor to blow out any debris that could attract vermin.

Indo Farming

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