It’s almost that time of year again to pull the combine out of hibernation, before being pushed to its limits for another harvest. Given that the harvest period is so short, it is essential these machines are thoroughly checked over and given a good service before harvest starts to minimise the chances of downtime later in the season.

In April, we encouraged combine owners to make a special effort this year and get machines serviced early to avoid possible part or labour delays as a result of COVID-19.

If not already done, then now is the time to pull these machines out and get them running well for the harvest ahead.

New Holland CX series combine.

Now that things are continuing to return to some sense of normality, the logistics surrounding the supply of spare parts and machines are in a better position than forecasted this time last month, but still not where they should be.

Carrying out general pre-season maintenance well in advance is good practice at the best of times, meaning you are not left waiting last-minute for the delivery of spare parts and components, especially for the less common parts that may not be on the shelf at the local dealers.

The New Holland TX series still proves popular across the country.

Good practise is to prepare for the worst and hope for the best. The previous season will often greatly influence the maintenance bill for the season ahead: if it was a tough year with wet unfavourable weather, this will have taken its toll on a combine’s internals.

We caught up with Alan Murtagh of Armstrong Machinery to go through some of the typical annual combine service procedures and to get some tips on what to look out for.

Alan Murtagh, combine technician with Armstong Machinery.

We looked in particular at the common New Holland TX and CX series machines. Regardless of brand, size or age, all employ roughly the same principles of operation.

The New Holland CX and TX series are quiet similar machines underneath from a service point of view.

Caution

While newer machines often tend to be looked after by the dealer as part of an agreed service plan, older machines are often owner-serviced.

For the less mechanically minded, even a thorough inspection and taking note of issues as they arise could identify a potential problem before it becomes a major issue.

This is good practice even if just to inform the dealer of what parts may be needed upon call-out.

A word of advice would be “if in doubt, don’t take the chance”. That applies to all aspects of checking, maintaining, servicing or running of a combine.

For ease of explanation and a straightforward procedure, we split the combine into its different areas and focus on the components associated with each.

We started with the engine before moving on to the header, threshing, grain separation and grain handling.

Before starting the pre-season service procedure, ensure the combine is thoroughly cleaned from top to bottom.

This is often a painstaking task requiring some time given the numerous nooks and crannies in which dirt can gather. Alan explained that the best thing to do first is run the combine.

Listen

While doing this, listen out carefully for unwanted noises which may indicate bearings beginning to fail, loose belts or chains, etc. You should not come into close contact with any moving parts while the machine is running. A trained eye and ear proves useful here.

Engine and transmission

Once the machine is powered off and isolated, the service can begin. As the engine has run for a number of minutes, its fluids are now warm and are therefore easily drained, so it may make sense to start here.

As with all engines, this is a fairly straightforward service procedure. Alan noted how all filters need changing each season, apart from hydraulic oil filters which should be replaced every second season.

Regardless of engine hours, the engine should get a full oil and filter service before every season.

These annual filters include engine oil filters, fuel filters, air filters, cab filters, etc. Once filters are changed and new engine oil has been used, check all fluid levels and for leaks after the machine has run again for a number of minutes.

The rotary screen drive belt should be checked and the screen working properly.

The belts associated with the engine, including the fan belt and the belt driving the rotary screen, should be replaced every one to two seasons, as failure of either one could result in major problems.

Both fuel filters should also be replaced every season.

Header

It makes sense to work from front to back, so starting with the header, its overall reel and tine condition should be assessed for damage or wear.

Damaged or blunt knife sections on the cutter bar need replacing. The same goes for cutter bar fingers too if damaged or missing.

Depending on the season, headers can be subject to tough conditions so check the header up and down for any damage or wear.

Auger fingers should be checked and be in good order with no excess play. These are all generally cheap-wearing parts that play a large role in machine performance.

The auto-float skids underneath the header should be checked for wear and that all are in good condition.

Auger fingers help with crop flow into the elevator and should be replaced if a lot of play is present.

Auger chain

Moving to the ends of the header, the auger drive chain should be examined for wear and that its tension is correct.

This tool measures chain wear. If the chain is completly worn, the tool will slot down into the chain's links.

Similarly, the cutter bar drive belt should be in good order with the correct amount of tension.

The cutter bars’ wobble box should have its oil level checked annually and replaced every second season.

Threshing

The threshing procedure starts once the crop enters the elevator chamber. Assess the condition of elevator bars or slats and their chains, tension or replace if damaged or badly worn.

Elevator chains and bars should be checked for wear or damage and that their tension is OK.

Adjust chain tension evenly that the bars halfway back on either side are touching the elevator floor. Once each chain tensioner is out to its maximum, a link may be removed off the chain and the tensioner adjusted accordingly.

These bars can run on nylon wear pads which naturally wear over time. If badly worn or missing, they should be replaced.

Moving to the main drum, individual rasp bar condition should be checked. A good visual guide is to set the concave to 10mm, for example, and then insert a 10mm plate to gauge the amount of wear.

Naturally the middle of each rasp bar will show more wear as result of crop infeed from the header. If the heads of the bolts holding on each rasp bar are heavily worn, then it may be time to consider replacing rasp bars.

Alan explained how rasp bars and concaves typically have a long lifespan, ranging from 1,700 to 2,000 hours.

Inspect the overall condition of the drum that there are no cracks or damage present.

Check the concave for broken wires or bars.

This particular machine has had new rasp bars and a new concave fitted.

A long working life is generally the norm unless a foreign object has entered and done harm. Often, if rasp bars are being replaced, then so too will the concave.

Because this is the primary threshing department, it needs to be in good order. Rubbers around the grain pan should be present and in good order. Replace if damaged, as these simply prevent the loss of grains.

When in this general area, open and empty the stone trap. This should be done on a regular basis throughout the season too.

From the side of the machine, drive belt condition should be checked for both wear and adequate tension.

It often proves worthwhile to slacken all belts and check idler pulleys for unwanted bearing movement. The drum variator, and all other variators, should be checked thoroughly for oil leaks and greased.

When the service procedure is complete, it is a good idea to change drum speed from minimum to maximum while the machine is running. This moves the variator across its range and distributes the grease, also ensuring it is not seized.

Separation

Grain separation is the process by which grain is separated from the straw before going into the grain tank and the straw exits out of the back of the machine. The condition of the sieves should be checked and that each is moving properly.

Sieves should be free-moving and show no signs of damage.

To check the calibration of the sieves, set them to 6mm on the terminal. Then use a 6mm plate to measure the spacings inside the machine to make sure everything is as it should be.

The CX8080 we looked at, being a six-walker machine, means it is equipped with a return auger on both sides instead of just one.

The auger and pulley drive on both sides should be checked over. There should be no major signs of wear.

The shaker pans drive and eccentric bearings should be given the once-over, checking for failure. The fan variator should be greased up and moved in and out too, ensuring it is working as it should.

The clean grain elevator should also be checked. Every season, elevator chain tension slacks off. The chain conveyor should be tensioned so that the chain is just about movable on the sprocket at the bottom inspection hatch.

The clean grain elevator chain should be tensioned so that the chain can be just moved over and back on the sprocket at the bottom.

All associated drive components, such as belts and pulleys, should be checked over. Each of the straw walker’s bearings, top and bottom, should be checked for excess movement.

Each of the walker bearings should be checked for play.

Grain handling and chopper

The bubble-up auger in the grain tank is gearbox-driven. Gearbox oil level should be inspected and changed every second year.

As well as checking for wear and bearing condition, the grain tank's bubble-up auger gearbox oil level should be checked and replaced every second season.

The same goes for the unloading auger gearboxes and their associated sealed bearings should be checked.

Auger wear should be examined. Sharp edges and excessive space between augers and housing may indicate that the auger needs replacing.

Plenty of replacement knife sections and fingers should always be carried on the machine.

Typically, the unloading components require little maintenance given that they only run for short periods of time.

Chaff spreaders are usually maintenance-free, given that they are driven via hydraulic motor.

Chopper unit knives should be replaced or turned over if blunt.

If equipped with a chopping unit, then knife condition should be checked. Knives are typically double-sided so they can be reversed, increasing their lifespan.

Knife sections should be replaced if damaged or blunt.

Generally, when replacing blunt knives, opposite pairs need to be replaced to maintain balance of the rotor. Choppers often tend to be power-hungry, so it is important the drive belt is in good condition.

All belts and chain drives should be checked to ensure both wear and tension is right.

The condition of any belt can be deceiving and, in certain places on pulleys, tears may not be visible, so take the time to inspect belt conditions in multiple positions.

It is always worthwhile having a spare filter kit on the farm.

Replacing one belt may often mean removing multiple belts to gain access. It is often a good idea to replace whatever belts need to be removed to access the damaged belt for peace of mind and to save the removal procedure later down the road.

Regular greasing and good preventative maintenance will prevent costly surprises when it comes to servicing annually.