Combining: A case for more speed, less haste?

6 March 1998

Combining: A case for more speed, less haste?

Most combine drivers could cut their grain losses, go

faster and increase their output dramatically. Its all

a matter of correct maintenance and technique, as combine

training expert Tony Gardiner explained to David Cousins

YOU spend untold hours bashing out a seed-bed for it. You drill it, shell out a fortune on sprays and fertiliser and watch it like a hawk for 10 months. Then, on the day its ripe, you steam through with a badly-set combine, dropping a significant proportion on the ground to encourage diseases in the following crop.

Doesnt sound like you? Maybe not, but if Tony Gardiners combining survey is anything to go by, theres a fair chance it is.

Mr Gardiner has been an ATB combine instructor for the last 27 years. He runs courses on combine maintenance and set-up, as well as on minimising grain loss. Short (one-day) courses covering grain losses and in-field settings usually run before harvest. Longer courses that cover maintenance and settings and involve trainees working on their own combines take two days.

Those attending the courses are generally there for one of a number of reasons. It could be that the farm has bought a new combine, has taken on new land, is growing a new crop or has a student it wants to train up. Or else the owner or manager may simply be worried by the current level of grain losses.

For the last 20 years Mr Gardiner has also carried out a combine survey, visiting each recently-trained driver during harvest. He checks how well theyre doing the job, whether the machine is set up properly and how much grain they are losing. He even gives a cup to the best operator each year.

And heres the sobering thing. Of the hundreds of combines checked over the years, Mr Gardiner has only ever found one driver and one machine that could not be improved upon in any way.

The combines involved range from 20-year-old battle-scarred veterans to freshly minted items just delivered by the dealer. And the farms on which they work cover everything from small family units to 4000-acre spreads run by big farming companies. He visited 64 machines and drivers for the 1997 survey alone.

So what are drivers doing wrong?

The chief culprits, says Mr Gardiner, were poorly set-up machines. Concaves were often damaged and frequently set too tight. Drum bars were often worn or damaged and drum speed too slow. Fans were too slow, sieves too tight and header components like the feed auger wrongly set and causing uneven feed.

The result in almost all cases was that drivers were overloading the drive components and engine, having to go slower – often much slower – than the machine was designed for and losing too much grain.

Its all, he says, a matter of effort. Drivers must check grain losses and the sample regularly through the day to see if the grain monitor display and combine settings actually match the combining conditions.

Wear the paint

Crop conditions can change sharply during the day, he points out. Output can often increase by 20-40% as the straw and grain get drier. So grain monitors need to be reset to take account of the increase in throughput and the changed characteristics of the grain.

"I tell people that the most important adjustment on the combine is the steps," he says. "The paint must be worn off the steps. If its not, it suggests youre not doing enough checking.

"The combines themselves are getting much more efficient. But the increased use of electronics and grain-loss monitors makes people less inclined to get off their machines and check the machine is set up correctly in the first place."

One problem is that drivers can be too slavish about following the advice in the instruction book, he adds. "You have to remember that the manual has to apply to operators in Brazil, China and Mexico and has to cover all combining conditions. It cant always be right for the local operator – its only a guide."

A pinch of salt

His advice? While much of what is in the manual should be treated as gospel, some of the settings suggested can be taken with a pinch of salt.

"Take drum speed. The book may say 800rpm, but you might do better with 950rpm. As beater bars wear, too, you may need to increase speed by 50rpm/year. Theres no universal solution, though – it depends on crop variety and moisture and whether the product harvested is to be used for seed or malting where germination is of paramount importance, in which case sample damage must be kept to a minimum."

In a standing crop of evenly ripened, clean wheat, most machines and operators will do a good job and produce acceptable losses. But even then output can often be improved by making one or two adjustments to the machine.

But its when the crops flat to the deck, damp and with weeds growing through it that deficiencies in man and machine show up.

The differences in output, forward speed and grain loss between machines and operators here can be striking. The average weight of grain lost by the 61 combines surveyed in 1997 was 256kg/ha (232lb/acre). A really good operator can achieve loss rates as low as 46kg/ha (41lb/acre), while a poor operator in a laid crop can lose as much as 1680kg/ha (1500lb/acre).

Another shortcoming common to many combine drivers is to put too much faith in the grain loss monitor. They are excellent at showing losses over the sieves and loose grain in the straw, he says, provided they are calibrated for the crop and clean. But they still dont register the two biggest sources of loss – header losses and unthreshed heads in the straw.

"As part of the grain loss courses run before harvest, we get each trainee to bring a bale of straw from the previous harvest, shake some of the straw over an old fertiliser bag or tarpaulin and rub out 50 heads," says Mr Gardiner. "They are always amazed at how much grain is in there – sometimes 1000 grains in an armful of straw. Thats worth £12/acre, which certainly gets the boss excited!"

Age-old technique

He also suggests a couple of refinements to the age-old technique of jumping off the combine and scrabbling in the straw swath to find maverick grains.

&#8226 Lift some of the straw from the swath and shake off over a fertiliser bag. That will show how many threshed grains are coming through with the straw.

&#8226 Rub out 50 heads (not just one or two) to give you an accurate idea of how much unthreshed grain is being left in the ears. Fifty heads represents the average density of wheat growing on 0.1sq m (1sq ft) of field area, so adjust the number of heads to the thickness of your own crop. Typically, the range will be 40-60 heads.

&#8226 Use your existing system to count the grains lying on the ground. These are grains coming past the sieves or lost at the header. You will need to look between the swaths to establish what proportion of those grains are being lost at the header.

These techniques are only really of use if the straw is coming off the combine in a swath. If you are chopping and spreading both straw and chaff, missed grains from different sources will all be mixed together.

Pretty frightening

One way round this, he adds, is to stop the chopper and spreader for a distance of 100m and then carry out the series of checks already mentioned.

When it comes to translating these high grain loss figures and slower-than-ideal forward speeds into hard costs, they can look pretty frightening.

"On average, we were able to reduce grain loss by 75%, equivalent to 195kg/ha (174lb/acre)," says Mr Gardiner. "Thats worth 18.50/ha (£7.50/acre), which over a days combining (24ha/60acres) amounts to £450.

"We also managed to increase forward speed (ie output) by an average of 19% (0.7mph) over all the combines tested. That means an extra 6ha (15 acres) could be cut in a 10-hour day.

"In output terms that increase could range from 40t (4.5ha)/day for a 5.5m (18ft) cut combine to 83t (9.3ha)/day for a 7.6m (25ft) cut machine."

The cost of training, he reckons, works out at about £200 for each operator. That figure was paid back after just 2.5 hours, while the benefits (fewer losses, greater yield, no green stripes in the field) should go on for ever.

For details of courses etc, contact Tony Gardiner on tel (01379-642661) or fax (01379-641172).

Above: Where once farms had a couple of combines, many now rely on a single large machine. So efficient operation is vital. Right: ATB-Landbase instructor Tony Gardiner (left) on one of his combine training courses.

Most combines do a good job, but theres always room for improvement.

Checking for grain loss behind the combine needs to be done regularly and thoroughly. As well as searching for grain on the ground, rub out at least 50 heads to check for poor threshing by the combine.

Combines were often going much slower than they were designed far, simply because they were not correctly set-up.

Good operators will check that the grain loss monitor is correctly calibrated.

As part of the grain loss course, each trainee brings a bale from the previous harvest and shakes out some of the straw over a tarpaulin. They (and their bosses) are often amazed at how much grain comes out!