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Noknroll

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Reply with quote  #1 
Anyone here able to provide gear and pinion teeth count from the attached info.
The yellow highlighted italic number in the word doc are my calcs.....assuming the other numbers i used from the part number are a correct assumption......264 teeth seems too big but I'll stand corrected if its right
docx SEW Gearbox.docx     
EV001 - Gearbox Tag.jpg

Vibe-Rater

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Reply with quote  #2 
Hi Nok, 264t does seem high.  Are you sure it is a 2 stage? (not 3)

I usually start with a high res signature on input and strobing or Speedvue very accurately.  Also do this on the output. At 61 rpm you should still see the synchronous gearmesh. Fmax at least 300x.

And set up and extra shaft in between taking a guess. John from PA has a formula for guessing.  Something like square root of x but I can't remember the number.

But those Z numbers must have been from a manual yeah? In which case all you need to do is confirm the 264t with hi res output shaft point.

Let us know how you go. rgds


John from PA

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I think you best go back to the SEW people and request the information.  Based on the total ratio of 24.19 I think you are missing a reduction in your calculations.  You are assuming a double reduction and I suspect it is a triple reduction.  Typically in multiple reductions each ratio is held to about 3:1 (more or less) so with a triple the total ratio could be about 27:1.  You also would not generally want a 17 tooth pinion in mesh with a 264 tooth gear as it would present a very skinny pinion which would be subject to deflection.

See the attached parts list for the R147 which also shows a triple reduction.

By the way there is an SEW site where you can input serial number and access gearbox details but it doesn't seem to work with the serial number off your nameplete.  See http://productid.sew-eurodrive.com/?lang=en.


 
Attached Files
pdf R147 parts list.pdf (106.46 KB, 22 views)

Danny Harvey

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Reply with quote  #4 
Eurodrive is normally very cooperative in giving out the required data.
Noknroll

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Reply with quote  #5 
Thanks All
I haven't physically seen the gearbox yet, but,
I've built a machine assuming the teeth from part numbers and 264 for the final.
It will soon be apparent if adjustments are required. Going to site next Wednesday.

John From PA 
I tried your link to site where I can enter details, it appears it only accepts motor details, like you said it didn't work with my gearbox id numbers ( didn't have the correct fields for gearbox number) . Anyway I punched in the motor numbers and only generated what is on the motor plate anyway, so no further knowledge gained.

Thanks again




EDIT
Danny I contacted the local SEW-Eurodrive and they were happy to send me the requested info. Now I just gotta wait and see if they deliver
Danny Harvey

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Eurodrive does some pretty weird things with their gears sometimes, too.  You can probably tell how many reductions it has by looking at the nomenclature in their catalog.  If I recall right, the D means double reduction and that sounds right to me.  The V means vertical, I think. Most maufacturers will do about 6:1 in each reduction. John's reference is most likely framed from his time doing big gearboxes where design criteria were stricter than what is used in small, mass produced stuff like this.

I have seen Eurodrive and manufacturers of similar drives use what is called a "shell pinion"  with as few as 9 teeth on the high speed pinion.  When I competed with them selling Sumitomo Cyclo gearmotors, they used it as a hit on Eurodrive saying that it could fracture but I don't really know if that was true or just a sales pitch. I wouldn't expect to see a 9 tooth (or a 17 tooth) and an 264 tooth in mesh.

That said, using the same casings and center distances for a multitude of ratios makes people have to do some funny things.

They won't treat it as an emergency but they will probably respond.  If they don't, let me know.  I've got a close contact at Eurodrive who will get it.
Noknroll

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Reply with quote  #7 
Thanks Danny
The info below turned up quicker than expected.
it appears the final ratio at approx 5:1 is between your and Johns 3:1 & 6:1
while second reduction is almost bang on 3:1......so, no hard and fast rules at SEW
I also monitor some voith box's with 9t on the high speed pinion
Now I'm off to edit the machine I created earlier[smile]
Wheat intake E1 gear info.png 

John from PA

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Reply with quote  #8 
Quote:
Originally Posted by Noknroll
it appears the final ratio at approx 5:1 is between your and Johns 3:1 & 6:1 while second reduction is almost bang on 3:1......so, no hard and fast rules at SEW
I also monitor some voith box's with 9t on the high speed pinion.
Now I'm off to edit the machine I created earlier[smile] 


There are no hard and fast rules which is why I stated each ratio is about 3:1 (more or less).  There was something years ago, I believe put forth by Technical Associates of Charlotte, that was called Speed Increment Factor (SIF).  I do not know why it was called SIF as it is simply the ratio of each stage, all stages being equal ratio, that would yield the overall ratio.  So for your ratio of 24.19 and a triple reduction, the SIF would be 24.19^(1/3) = 2.892.  In other words 2.892 * 2.892 * 2.892 = 24.19.  To get that same overall ratio of 24.19 with a double reduction the SIF would be 24.19^(1/2) = 4.918.  So 4.918 * 4.918 = 24.19.  That actually could be a design possibility but you had stipulated potential numbers for the 1st stage reduction that drove the 2nd reduction too high in ratio.  As I said, higher ratios tend to create skinny pinions that exhibit high deflections due to bending as a result of gear forces.  The actual science behind picking a tooth combination looks at multiple factors that are well beyond simply the division of two numbers.

Are you sure you have a pinion with only 9 teeth?  That would be exceedingly difficult to cut.
Noknroll

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Reply with quote  #9 
John
Yes, sure it's 9t. Spec sheet says it and vibration confirms it.
They are approx 35 year old box's driving coal conveyors in a Power station
John from PA

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Reply with quote  #10 
Quote:
Originally Posted by Noknroll
John
Yes, sure it's 9t. Spec sheet says it and vibration confirms it.
They are approx 35 year old box's driving coal conveyors in a Power station


Sounds like an application where accuracy is not essential.  Reread my previous post as I've added some additional info.
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