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Frequently Asked Questions

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If Filler Plates are such a good idea why don’t the combine manufacturers supply them?

Case IH, Massey and John Deere combines all have filler plates available. The concaves were really designed for corn. As a result they don’t have very much bar over the wires. When filler plates are used on these concaves there isn’t enough edge left to hold the heads in place long enough to be threshed.

To achieve proper threshing with the concave two things are critical. One is the amount of bar over the wires. You need enough to hold the heads while they are being threshed and the second is the filler plates which are needed to stop the heads from being pushed through the wires before they are threshed.

To illustrate the need for filler plates think about threshing a few heads of wheat in your hands. If you keep your fingers closed while rubbing your hands together it is easy to thresh the wheat. If you spread your fingers apart you can’t thresh any longer because the broken heads are forced through the openings between your fingers–just like broken heads and white caps are forced through the wires in a concave without filler plates.

Now to illustrate the need for more steel over the wires hold a piece of glass in one hand and with your other hand rub a few heads of wheat against it. It won’t thresh because the surface is too smooth. That is why filler plates don’t work in the factory concave that comes with your combine. When filler plates are added the threshing surface becomes too smooth because there isn’t enough bar over the wires.

Harvest Services Concaves are manufactured with more bar over the wires so you can use Filler Plates.

NOTE: Occasionally we hear from farmers who tried Filler Plates that didn’t work. In 99% of these cases it’s because the Filler Plates were installed on top of the wires on a factory concave. With factory concaves install the Filler Plates under the wires. Filler Plates will help every time in small grains, even if the concave is worn out, but they are no substitute for a concave in good shape.

Do any combine manufacturers build their concaves to a perfect circle?

From the 21 Massey combine on up, the Massey Ferguson Company manufactured their concaves in a good circle. They were all riveted and bolted together so they had no welding warp. Of all the concaves manufactured by all the different combine manufacturers the Massey Concave is as good as you can get without precision boring the concave.

Do I need the wires in my concave when threshing cereal crops and what about corn?

When threshing wheat you don’t need the wires, period. The only reason HARVEST Concaves have wires is to provide a mounting method for our Filler Plates.

With corn we’ve run tests with wires and without wires and we couldn’t tell any difference. During 1990 some of the testing farmers reported a cleaner sample in the tank and a whole cob out the back with no wires in the concave. Other farmers reported no difference.

We think it all boils down to the conditions at harvest time and the weather conditions while the corn matured.

Our 2″ wire spacing seems to work best in most cases. Every year we sell more concaves into corn country and the feedback is positive.

If I set my concave to zero clearance at the back, won’t that grind up my straw and take more power?

If you have set your concave to form a wedge, as we recommend and your combine seems to require more power and you are grinding up straw it is because the clearance at the front of the wedge isn’t big enough. It isn’t because of the zero clearance at the back of the concave. When your concave is set to form a proper wedge, about halfway up the circumference of the concave, the cylinder bars will have sliced through the crop material and the straw gets bunched up between the cylinder bars while your grain is accelerated through the openings in the concave.

Cylinder bars are designed to accomplish all this in a fraction of a second. The design of the cylinder bar is a compromise between a rubbing type of surface that will thresh your crop at the front of the concave and a curved surface that will push the straw up the concave while accelerating the grain outwards through the openings at the back of the concave.

Won’t shimming and truing my cylinder bars throw my cylinder out of balance?

When you shim the cylinder bars all of the bars are the same distance from the center of the shaft and it actually helps balance the cylinder.

How often should I check the rear of the concave for zero clearance?

Some combines have weak concave support linkages and the concave will often work down over the course of the day. As a result, the concave setting should be checked every morning and any time walker loss increases. An increase in walker loss is a sure sign that the back of the concave is not at zero clearance.

How fast should I run my cylinder with a new Harvest Services Concave ?

At least one RPM less than the first cracked kernel or seed in the tank. Harvest Services Concaves are more efficient and you can usually run your cylinder a couple of hundred RPM slower than you had to with the concave that came with your combine.

After you’ve slowed the cylinder to eliminate cracked grain you may still be getting white caps and there are three things you should keep in mind before speeding up your cylinder again.

1. Filler Plates – in order to be threshed properly, your crop must be held in the concave/cylinder wedge long enough for the cylinder bars to rub the seeds out of the head. Always use enough Filler Plates to get proper threshing.

2. Insufficient crop material in the cylinder/concave wedge – For effective threshing you need enough material in the cylinder/concave wedge that it is tight enough for the seeds to be rubbed out. To ensure enough pressure either travel faster so more crop gets into the combine or reduce the clearance at the front of the cylinder concave wedge. Remember 3/4 of an inch is adequate for most crops. Only super bumper crops need 1″ while a light crop may require 1/2″.

3. One high cylinder bar will give you white caps – Make sure your cylinder bars are true or shim as required.

I’ve done everything you’ve told me. I’m getting a cleaner sample but the kernels look as if they’ve been crushed.

Crushed kernel damage can be caused by worn flyting in the return or clean grain augers. As the flyting wears it bends back and can’t auger properly. As a result your grain will bunch up in the auger trough, six or more inches deep, just before it dumps into the paddle bucket. The grain then spills into the sprocket and gets crushed between the sprocket and chain at the center of the return or clean grain elevator.

Most farmers do check the return and clean grain elevator chains for wear. By the time most have been used for 2,000 hours the clean grain and return elevator chains will have been replaced but unless the worn flyting is also replaced not only will you get crushed kernel damage and you’ll also stretch those new clean grain and return elevator chains.

Because the clean grain auger carries a lot more grain than the return auger, or at least it is supposed to, it will wear faster.

Five Rules For Top Combine Performance

1. Constant Even Feeding – No combine can perform unless it is set properly and unless your combine is receiving a constant even supply of material it will be impossible to set.

2. Keep the Combine Full – When the new draper headers were first being tested a lot of farmers were doubtful about their combines ability to handle the material from a 36, 42, or 50 foot header. But these giant headers surprised the most skeptical farmers. Even when the size of the header doubled the farmer only had to reduce his speed by about 305. In every case there was a net gain in acres combined per hour plus the combines performed better. Traveling a bit slower is also easier on your equipment.

3. Concaves – If you’re not getting proper threshing at the concave all you are doing is passing the problem on to another area of the combine that is ill equipped to deal with it.

For proper threshing your combine needs a precision bored concave and the cylinder or rotor must describe a perfect circle. With conventional combines you also need Filler Plates, when harvesting small grains. Rotary combines also need Cover Plates in the majority of small seed crops.

4. Wind – To make pressurized air the inlet to the fan must be larger than the outlet. Make sure the bottom sieve doesn’t interfere with the wind to the top chaffer.

In crops with chaff and straw the top chaffer requires uniform air pressure across its entire width. The HARVEST Air Foil Chaffer works best in separating your grain from the mat of chaff and straw.

5. Returns – When a combine is not performing properly the return system often becomes overloaded. If you find yourself slowing down because of an overloaded return, don’t blame the return system. It was never designed to handle the high volume of unthreshed heads that you get from a bad concave or the high volume of clean grain that results from an improperly positioned bottom sieve.

Worn Concaves - Why it is so important to replace them?

As a concave begins to wear, the edges become dull and rounded, reducing the friction on your crop as it is threshed. With the loss in friction the crop slides by and the heads simply are not held in place long enough to allow for proper threshing.

A loss in the threshing performance of the concave results in white caps which leads to more material being returned and an increase in grain loss over the shoe or rotor.

To reduce the white caps that have been caused by the worn concave, many operators increase the speed of the cylinder or rotor. This may help reduce white caps but it will also increase kernel damage and do very little to reduce the loss over the shoe in the form of unthreshed heads.

Increasing rotor or cylinder speed is a poor solution to the real problem of a worn concave.

Combines are just too expensive and harvesting season too important to take your concave for granted.

Every year, long before you go to the field, the concave should be removed and the entire threshing area carefully inspected. You have to take the concave out to inspect it properly. You know that all parts do wear and will have to be replaced at some point in time. It is just a lot easier to do it at your leisure rather than the middle of the harvesting season.

If the concave is bent and twisted or the edges are rounded off, it is time to either replace it or have it rebuilt by a reputable concave rebuilding firm. Unlike rub bars most concaves are not hardened or chromed and as a result they don’t last as long as rub bars.

All concaves should be inspected once a year and they will probably require some serious attention after 400 hours if you pick up a swath or 600 – 700 hours if you straight cut. Because rotary combines are capable of processing more bushels per hour they do wear faster and should be inspected more often.

Harvest Services Concaves are manufactured with more bar over the wires to give you a longer lasting concave. With more bar over the wires your Harvest Services Concave can usually be re-bored once. After the edges become rounded you don’t have to buy a new concave. By re-boring you get new concave performance for a fraction of the replacement cost.

Harvest Services Concaves have square edges which retard the crop to allow for the proper threshing and separation of all your different crops.

By adding or removing the Filler Plates on Harvest Services Concaves for conventional combines or the Cover Plates for concaves on rotary combines you can easily fine tune the concave to achieve the proper balance between threshing and separating to keep returns at acceptable levels and maximize the performance of your combine.

With a more aggressive concave the cylinder or rotor speed can be lowered to reduce kernel damage. The improved threshing and separating ability of Harvest Services Concaves increases your combines’ capacity, thereby lowering your operating costs.