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Author Topic: Questions about pulleys  (Read 6118 times)

capthook

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Questions about pulleys
« on: May 30, 2008, 05:57:23 AM »
Hiya!

I'm trying to step-up a low RPM device to a higher RPM to create electricity using a pulley setup.

Having never done a build with a proper pulley setup ? I?m a noob with this aspect.

What is the best/most efficient way to do the pulleys?

A) V belt, flat belt or cable style pulleys?  (I vote Vbelt)

B) Ratio. 1:4 ? 1:8 ? 1:12 (1:4 is the cheaper/more manageable option ? but is it enough?)
Is there some kind of performance loss the larger the ratio?

C) Mounting:
1) fixed shaft with a bearing in the pulley ? like an idler pulley.
You (I ) can?t (seem to) get a 12? idler ? so can you properly mount a bearing inside a 12? pulley?
If the pulley has a 3/4" bore with a fix screw - will a 3/4" outer diameter bearing fit properly?

2) rotating shaft with pulleys fixed to shaft.  Then what kind of bearings at the support ends?  Press fit?  Pillow block? Self-aligning needle roller?  Flange mount?
What about a bushed pulley?

And which option between 1 and 2 would be the most efficient?
Option 1 uses 1 bearing x 2 pulleys= 2 total bearings
option 2 uses 2 bearings x 2 pulleys= 4 total bearings.
Will option 1 be better because there is 1/2 the bearing friction?
And option 1 you don't have to worry about perfect shaft alignment.  With option 2, an out of whack shaft (even barely) will seriously compromise performance. (difficult to get it perfect) but then again - self-aligning bearings could solve this - but which bearings offer this?

And what about a bicycle wheel for the large pulley ? Or will slippage/tracking be a problem compared to a real V belt pulley? (I vote V belt better - but costs more - especially over 12")

MSC has a great selection/prices for all types of components.  I?ve spent considerable time finding this supplier and searching/specing these.

Here are links to pulleys and bearings I?ve considered:
(links to items don't always seem to work - goto the site and search the item # if not)

12? v belt pulley:
http://www1.mscdirect.com/CGI/NNSRIT?PMPXNO=1647617&PMT4NO=0
Item # 00053686

3? v belt idler pulley:
http://www1.mscdirect.com/CGI/GSDRVSM?PACACHE=000000056592053
Item # 35428341

Single bearings:
http://www1.mscdirect.com/CGI/GSDRVSM?PACACHE=000000056591686
Item # 35433374

Mounted bearings list:
http://www1.mscdirect.com/CGI/N2DRVSH?SISECT=0002007308&SIS0NO=00000853358


Mostly ? what is the best/most efficient way to mount the pulleys?

Fixed shaft?  Or fixed pulleys?

And if fixed shaft ? what kind of bearing ? press fit, pillow block, etc?

Any help/comments/insight would be greatly welcomed.

I will post pics of the setup once I get it figured, parts ordered, and built

Attached is a pic of a hack plywood setup for testing....
and a pic of my coil setup in 3phase star...

CH

Paul-R

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Re: Questions about pulleys
« Reply #1 on: May 30, 2008, 04:11:12 PM »
Hiya!

I'm trying to step-up a low RPM device to a higher RPM to create electricity
using a pulley setup.
Much depends on the power you need to move. There are toothed pulleys
and "v" pulleys.
Your best bet would be to speak to a technical sales rep at a pulley
manufacturer or importer. They may well solve your problems for you
and even put a copuple of free samples in the post for development.
http://www.sdp-si.com/eStore/CoverPg/Pulleys.htm?wcw=google&gclid=CObDuZGzzpMCFQ6S1Qodg118kA
Paul.

capthook

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  • Posts: 469
Re: Questions about pulleys
« Reply #2 on: June 01, 2008, 02:56:36 AM »
Thanks for the reply Paul.

The weight moved is rather small so I felt a toothed pulley was overkill...

SDP seems a good supplier as well - but they have been "out of stock" of large pulleys for months... I think they must not "actually" carry them.

About a month ago - I tested the two options...
1) fixed shaft - rotating pulleys
2) rotating shaft - fixed pulleys

My results were that option 1 (fixed shaft) was far superior in efficiency.  I attributed the majority of it to the shaft being slightly out of alignment.  Without exacting construction - I find this difficult to overcome - especially with the tools I have available.
Thus my question of "self-aligning" bearings.

As such - for now - I'm going the route of the fixed shaft, rotating pulleys.

It is my goal to squeeze out every drop of available efficiency.

I have a 3" idler pulley coming in the mail - as well as a 12" small bicycle wheel (it was only $10 compared to $50 for the 12" vbelt pulley - I'll see how it works... as I'm not sure of the final ratio and didn't want to "waste" money)

I'm still interested in opinions/advice on all points listed in original post if there are any takers......

CH

Thaelin

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Re: Questions about pulleys
« Reply #3 on: June 03, 2008, 07:03:12 AM »
   Well, I have used both V and flat belt. If you have no problem with slippage, then V will do ya. I see no reason to "time" the pulleys to each other on a gen head. If you want to go that route then you can use the timing beale on overhead cam engines for the task. They have teeth and the upper sprocket is removeable.
   I am in the go for a five to one spin up and will be using v pulleys and the seal ring from a five gallon pickle container for the time. You could even make your pulleys out of wood if you had to and they will work quite well. Was done in the early times a lot. Just wore out easy. Then there is always a can of belt dressing that you spray on and makes the belt really stickey.

Lots of ways to go.

thaelin