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Maybe a Fix for Bolens 1250 Hydro Cooling Fan

bolens; 1250; fan

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#1 framesteer OFFLINE  

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Posted February 12, 2016 - 02:12 PM

Another failed part I ran into with my Bolens 1250 restore was the hydro cooling fan (1719006).  This fan had failed in several places and had been welded poorly by the PO.  The fan was a formed sheet metal part about 3/16” thick.  I believe it was initially designed as a press fit on the 1.5” diameter u-joint yoke.  In trying to find a replacement, I came up empty.  So I built a replacement assembly using an thin appliance fan and a split shaft collar.

 

First, the fan center was machined out to match the 1.5” yoke.  Then I drilled five holes for 10-32 allen head machine screws in the fan and the split collar.  The assembly is shown in the attached pictures. 

 

My major concern is the amount of vibration that the u-joint will impart to the thin fan.  There would be two theories on that: 

1.      One would be to make it out of heavy material like the original fan.  Obviously, there are a lot of failures of this design.  The fan may have been so rigid that the vibrations and rotation speed just caused it to fatigue to death.  This is the theory the Bolens engineer used, probably because he needed enough material to press fit the fan on the u-joint.

2.      Two would be to make the fan thin enough to flex with the vibrations of the shaft.  This is the “airplane wing” theory -- the part is designed to flex so it won't fail.  This is the route I went, mostly because I could find the parts.

 

Time will tell if this works.  At least for a time the hydro will be cooler than before.

 

IMG_2328.JPG IMG_2331.JPG IMG_2330.JPG IMG_2329.JPG


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#2 BolensChrisUK OFFLINE  

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Posted February 12, 2016 - 02:20 PM

Very neat job :thumbs:


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#3 Rainier OFFLINE  

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Posted February 12, 2016 - 03:03 PM

That's an interesting fix. Maybe that's why the newer models were made out of plastic.
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#4 LPBolens OFFLINE  

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Posted February 12, 2016 - 03:09 PM

Very neat and tidy fix. Looks like it should work just fine.

 

Where did you get the fan? And the split collar?


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#5 Bud W OFFLINE  

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Posted February 12, 2016 - 03:48 PM

I need to try that on my 1886 that I plow snow with, it spit a blade out while plowing last week.


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#6 Austen OFFLINE  

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Posted February 12, 2016 - 04:16 PM

Great ingenuity and clean work! :thumbs:  :thumbs:

 

Thank you for sharing the photos with us.


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#7 framesteer OFFLINE  

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Posted February 12, 2016 - 05:57 PM

The fan came from PartStore.com

Supplier                 Description                                                                          Part #                   Price

Supco                8" CCW ALUM.FAN BLADE                                                  FB105                   $7.39

 

 

The 1.5" shaft collar (one piece collar, only split on one side) came from Fastenal. I don't have the part number.


Edited by framesteer, February 12, 2016 - 05:58 PM.

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#8 dthomp17 OFFLINE  

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Posted February 13, 2016 - 09:07 AM

I like it.  Good job.



#9 HANKG ONLINE  

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Posted February 13, 2016 - 01:05 PM

Nice  engineering plan neat finish



#10 jdcrawler OFFLINE  

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Posted February 13, 2016 - 06:09 PM

Just an ides an the vibration.

What about drilling the holes in the fan larger and inserting a short piece of rubber hose to act as a vibration bushing ?


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#11 Dan O OFFLINE  

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Posted February 13, 2016 - 10:02 PM

That's a very nice looking piece of work. Good Job.






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