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915 combine air flow


tw77
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We have a 915 combine we use to harvest wheat with. We disabled the chopper and spreader so that it lays the straw in a windrow ready to square bale. But we’re having problems with the fan not blowing the chaff out very good. I’ve tried adjusting the fan belt but it doesn’t seem to make much difference. I think it’s a poorly designed fan system and should have a fan blowing straight in from the bottom. This system has a fan pulling air from the side and blowing down and then back up through the ductwork. We’ve been thinking about redoing some of the ductwork and using a high speed 12 volt fan mounted closer to he bottom of the machine tp really push air through and hopefully get most of the chaff out. Has anybody done this or anything similar? We only do about 30 acres of wheat per year. The machine is in good shape otherwise so I hate to spend the money getting another combine. We have a 1640 for corn. We tried it on wheat but it absolutely destroyed the straw. I’m just curious if it’s possible to get a dc powered fan to blow that much air for the amount of time. 

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25 minutes ago, tw77 said:

We have a 915 combine we use to harvest wheat with. We disabled the chopper and spreader so that it lays the straw in a windrow ready to square bale. But we’re having problems with the fan not blowing the chaff out very good. I’ve tried adjusting the fan belt but it doesn’t seem to make much difference. I think it’s a poorly designed fan system and should have a fan blowing straight in from the bottom. This system has a fan pulling air from the side and blowing down and then back up through the ductwork. We’ve been thinking about redoing some of the ductwork and using a high speed 12 volt fan mounted closer to he bottom of the machine tp really push air through and hopefully get most of the chaff out. Has anybody done this or anything similar? We only do about 30 acres of wheat per year. The machine is in good shape otherwise so I hate to spend the money getting another combine. We have a 1640 for corn. We tried it on wheat but it absolutely destroyed the straw. I’m just curious if it’s possible to get a dc powered fan to blow that much air for the amount of time. 

Okay stop your thinking on what your doing. We ran with chopper ahead and dropped straw with a 915 a lot. Here is some advice on how to fix your problem. First thing on a 815 or 915 you have to be able to turn entire threshing system by hand when you grab on back side of your current fan. Every day when greasing machine everyday grab on backside of fan and turn. If it doesn’t turn cylinder and walkers you have problems. This is your problem. You will need to pull belts off and this is super important. Check your pulleys for fan variable speed. They wear and don’t provide grip and speed for fan. Check under combine that every part of duct is in place. Also check inside of duct when when you pull the fan transition off. Now this is more important make sure the shaker and grain pan belt up front behind right side tire is good and adjusted. Also crawl in back of combine inspect sieves but take a garden hoe and clean the waffled grain pan of built up material. This is important this has to be clean and shaking well. The fan on side of your combine will provide enough flow it just needs more care than the tumble type bottom side fan. To give you priority, fan drive belt set good and tightened properly, fan drive pulleys good, grain pan belt good and pan clean. Then you need a shaft tachometer to set fan if I remember it is 1400 rpm for wheat. The fan system will clean if adjustments are right.

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And its not just air volume.... the air needs to hit the screens at the right points and evenly.   I've read an old ag text book about airflow over chaffers....its almost an art.   You could put on a huge fan, that would clean terrible because it all blew on one edge!   

That said, I know nothing specific about the 915.

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Here are some pictures to help you in key areas. First picture gives you idea how air is supposed to go but this is 1st gen high profile machine.  Second is shaker pan drive that will slip. Third is fan pic of machine with fan. Parts diagrams are key drive components to fan. Underneath combine is adjustable deflection board also you really need a operators manual to adjust combine. Also make sure back of cylinder is up so you are threshing completely for corn and coarse crops on the cylinder combines you had to lower back.

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We had a few 914's in the area. Interesting they used the regular cross paddle fan like everyone else.

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5 hours ago, tw77 said:

 

 We have a 1640 for corn. We tried it on wheat but it absolutely destroyed the straw.

What rotor is in the 1640? Are you using disrupters in the concaves? That combine shouldn't tear the straw up that badly. I've done oats and barley with my TR86 (S3 rotors which compare to the specialty rotor for CaseIH.) and had no complaints on the straw. 

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1 hour ago, FarmerFixEmUp said:

What rotor is in the 1640? Are you using disrupters in the concaves? That combine shouldn't tear the straw up that badly. I've done oats and barley with my TR86 (S3 rotors which compare to the specialty rotor for CaseIH.) and had no complaints on the straw. 

I take that back. It was the 1460 that we had before the 1640. But as far as I know it was the stock setup. That’s been a while ago but we slowed the rotor and did some adjustments but never actually changed any parts

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38 minutes ago, tw77 said:

Thank you dale560. I’ll have to check that over about the fan and belts 

You really have to look at those fan sheaves also. On Dads we replaced the pulley sheaves with a better used set. The belts lasted longer and fan speed was more consistent. We ran a 815 and 915 over a lot of acres. Learned the little things to solve your headaches with them. You should be with 1 percent caps of what your rotary will do. 

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if anyone has a book written by Ray Steuckle called " Combine settings for better harvesting" it had a story about the 8 and 915 and how you had to adjust the wind veins to get even distrubution. I used to have the book and will try and find it and perhaps try and copy the 915 fan settings for you

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5 hours ago, hagan said:

if anyone has a book written by Ray Steuckle called " Combine settings for better harvesting" it had a story about the 8 and 915 and how you had to adjust the wind veins to get even distrubution. I used to have the book and will try and find it and perhaps try and copy the 915 fan settings for you

Oh gosh, I forgot about that book.  Same - a LOT of discussion about proper airflow.    That book was amazing.   

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5 hours ago, hagan said:

if anyone has a book written by Ray Steuckle called " Combine settings for better harvesting" it had a story about the 8 and 915 and how you had to adjust the wind veins to get even distrubution. I used to have the book and will try and find it and perhaps try and copy the 915 fan settings for you

Boy a book like that would have been great to have years ago. Never knew there was a book about it.

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