Combines Fan Duct Diffuser

[tbran]

are you talking about the 71373792 thingy or the 6 71174672 fingersIJ

 

[R_O_M]

Blimey, tbran, you were quick!!! Gotta consult the parts book out at our property to get the part numbers. The part originally removed were the plastic fingers that hang down from the top of the top accelerator air duct at the front of the sieves. The tin work we modified,curves from these fingers around and down to the fan, forming the upper fan duct.

 

[tbran]

In theory I understand the fingers were to prevent debris from going down the ductIJ but in practicallity, I wonder as to effectiveness. Maybe someone else has some info. On the other hand what is the restriction in total. The sheetmetal you talkabout could however be, I will try to do some crawling and look. Always appreciate new ideas. Sometimes we do things just because - like the mom teaching the daughter how to cook the christmas ham - first you cut off both ends, - why the daughter ask - mom said 'don't know lets ask granny - and granny said she always did this because she only had a small pan and the whole ham would not fit inside! So goes many things in our lives.

 

[R_O_M]

Figuratively have been cutting those hams for years and still wondering why we do some of those things! Those plastic fingers are a huge obstruction to the overall flow of air out of the duct. As well, as any basic air flow data will tell you, they create a lot of turbulence in the airflow in their wake just when a very even and smooth laminar flow is needed to maximize the sorting of the light material from the grain as it exits the accelerator rolls. That is why we removed the fingers very early in the piece. The fingers are mounted on the 20mm wide, folded down strip of the duct sheet. With the plastic fingers removed, this strip, right across the top of the duct, in the area of the highest velocity flow, we believe is now also causing some turbulence down stream and affecting the cleaning at the accelerator roll exit slot. We have now flattened this strip out. The N series have no obstructions at all in the duct and the top of the duct is smooth sheet right through to the accelerator roll exit slot. JR, down here in central Victoria has used both the N's and the R's in really fussy, very small pasture seeds and like myself, feels that the N series were much better at the primary cleaning at the accelerator rolls than the R's. A couple of small mods in this fan duct area will get us to where the N's were. I would still like to know if any body else has done this mod and what were the results please.

 

[turbo]

I believe the fingers are in there to equalize the air flow. Without them there would be dead spots. So i have been told.

 

[NDDan]

I believe them fingers became standard with the first R62 and 72s. I had heard the program to bring out the 62 and 72s called the fat 50 project. That is to bring out a fat R40-50. I believe this design of upper duct started with the first 40 and 50s and I find that finger devise in the 50 parts book with no reference to S_Ns. I could remember something about them fingers somewhere. What I found is in a 1994 school book they mentioned a kit for the R60-70s. The kit was a finger devise almost identical to what is in the R62-72s. It was a kit that could be put in if all other shoe and air system measurements were right and still having shoe problem. We never did install any but we did pull fans to adjust or stiffen upper cutoff just below fan choke. We also layed a straight edge on last few inches of ducting just before accelerator rolls. This last few inches of ducting was to run parralel with the floor under engine. I found many where this ducting was aimed down toward chaffer (in fact some nearly a foot ahead of the rear of chaffer). Without climbing back into a R62-72 I believe this is where major air stream would be headed without some sort of finger devise air defuser system. I have it hand written in that school book that the instructer of the class suggested it helped prevent blowing out heavy kernals. I believe if you straighten out ducting and match older design with last few inches running parralel to engine floor you will have as good or better than your original. Good luck

 

[R_O_M]

From our local Gleaner agent; One local gleaner owner has removed the plastic finger rake from the fan duct and placed the rake on a pivot shaft in the same position. He folds the rake up and out of the air stream when harvesting cereals and etc, and folds it down into it's normal position across the duct when harvesting canola. Seems a pretty smart and sensible idea to me! It also reinforces the idea that this rake considerably reduces airflow from the duct, allowing more chaff and etc to reach the sieves, possibly to the detriment of better cleaning over-all.

 

[R_O_M]

Sorry ! Just found out and should have added that an agent in South Australia produces a sheet metal mod to the upper fan duct for the R series that extends the fan duct sheet right through to the accelerator roll exit slot as per the N series. Plastic finger rake is removed completely. The reasons for the mod are the same as above, reduced and turbulent airflow from the rake. Incidently, I believe this agent also swears to the effectivness of Dan's mods to the front elevators.

 

[NDDan]

Is that Chris's dealership in South Australia. I'd thought he was in Victoria. It does sound like Chris had great luck with floor mods last year but don't know if he'll be able to give them much of a test this year. Hope to meet you and Rolf soon. Thanks for the interesting info. I believe I will be climbing onto a shoe one of these days to take a closer look at plastic finger rake area. Take care.

 

[R_O_M]

Am looking forward to meeting you, Dan.