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Discussion Starter · #1 ·
Got some new blades for the cleaning fan , upgraded to the later model blades. Mine may have been home made not sure, but they were more or less flat with only a small fold for strength . The new blades are 1/3 folded at approx. 15 degrees.
In my mind the fold would slope away from the direction of travel to expel the air outwards. If the fold sloped towards the rotation it would draw air in towards the axle . AM I RIGHT ????? please advise thank you
 

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Discussion Starter · #4 ·
From memory it should look something like this. Hope you can decipher it......
Yep the picture makes sense and I originally thought that way. But when I thought about them spinning I figured the bend would pull air towards the axle instead of it passing off the end of the blade into the shoe
 

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Discussion Starter · #5 ·
Not quite sure on your wording here.......

It should draw air inwards from the sides, and expel it rearwards to the sieves.
Yep hard to describe. But I understand the way it works pulling air in from the sides and pushing it into the shoe. The book shows flat blades , But I got the late serial number blades like your diagram. Spinning like your diagram shows makes my mind think the air would pull towards the axle instead of flowing off the blades.
I am happy to be wrong just want to know which way to fit them.
Clear as mud
 

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Spinning like your diagram shows makes my mind think the air would pull towards the axle instead of flowing off the blades.
I am happy to be wrong just want to know which way to fit them.
Clear as mud
Try them the other way.......... you never know, you might solve the problem of barely enough wind............ you may be the first to have ever tried it..............
 

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When I worked for JD back in the day when we were updating these combines we also trimmed the side openings so they were the same size as the fan housing and also installed deflectors in the bottom to direct the airflow.
 

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Discussion Starter · #10 ·
When I worked for JD back in the day when we were updating these combines we also trimmed the side openings so they were the same size as the fan housing and also installed deflectors in the bottom to direct the airflow.
yep recently learnt about the titan 2 upgrades and already have the deflectors installed and will vent the shrouds soon . is trimming the side openings pretty straight forward and wont weaken the structure ??
 

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Discussion Starter · #11 ·

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very informative. correct me if I am wrong but from that going to forward sloping blades will make them harder to drive but will produce more wind pressure at lower speeds and will also produce a more forward directed wind ??
I had a 7720 that puked a blade and I had to fix things. The bloke
above mentioned a kit, and if he installed them he should be of some
help, but not, it seems.

The fan improvement kit had new blades and it did enlarge the side
openings to allow more air into the fan. I had my dealer cut the sides
and install the kit.

One problem with the 20 series, is they did not have enough fan
and air through the sieves, a common issue and so they would lose
grain over the shoe. The 9000 series improved upon the fan
in a big way.
 

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very informative. correct me if I am wrong but from that going to forward sloping blades will make them harder to drive but will produce more wind pressure at lower speeds and will also produce a more forward directed wind ??
The forward curved blade drives air off the tip of the blade faster and increases the volume of air the fan can handle. For the cleaning shoe, this is a good thing. It won't increase the pressure under the sieve, but it will increase the airflow. A reverse blade will build more static air pressure for a given fan speed, but the air flow will be slightly less. A reverse bend blade is great for pumping air through a grain bin full of grain where higher static pressures are required. A forward curved blade will pump more air, but at a lower static pressure, such as a leaf blower where a large amount of air is used to move light material. A straight blade is the best of both worlds. If you look at the cleaning fan in a 9500 or 9600, they have a rather unique series of curves that Deere used to increase both air scavenging, (getting air into the fan,) and air volume required for the shoe and the precleaner. ( Only to leave huge gaps in the airways to the pre cleaner for all that extra air to escape!! :eek:)

The 7720 T2, and to more of an extent, the 8820 T2, required a lot of air for the bigger shoe, compared to the earlier models, and the small side openings were terribly inadequate to get any kind of air volume, evenly under the shoe to do a really good job of cleaning in high trash conditions. They tend to drive most of the air up through the middle of the shoe and leave the outside of the shoe short of air. Grind up some really dry canola and try to put everything over the shoe, and it fails miserably because you can not get an even flow of air under the chaff to effectively separate the canola. There just isn't a really good way to get a nice even, consistent airflow under the shoe to do the job. The increased side openings helped the 7720 quite a bit, allowing more air to get into the fan early and toward the outer edges of the shoe, but were not enough for the 8820 to get reasonably even airflow under the shoe. (Canola blows over in the center and sloughs over on the outside of the chaffer.)
 

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Discussion Starter · #17 ·
Thanks to all for all the input it has been educational.
Got it all rebuilt to new standards and with the upgraded blades it should throw more air . I will upgrade the shrouds later. It has new blades , bolts , bearings , supports and brackets.
I was going to reuse the brackets but once it was dismantled they were rubbish I say its been fixed up in the paddock in a rush one day.
Anyway I couldn't wait for brackets from states so manufactured some and managed to get good repetitive consistency I reckon.

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