>>
>> Paul,
>>
>> I'm looking for a cad (dxf) profile of the V grooves for
multi-groove
>> belts. Is this something you have?
>>
>> Thanks
>> Ken Bauman
>>
>> No but I have a multi V grove pulley set from McMaster Carr
>> I will be using on the turbo compound engine.
>> In .92 inches of width there are 10 grooves.
>> The depth is about .090". Hard to measure exactly. I might
>> be able to take it over to the machine shop and put it on
>> the optical comparator if it is real important to you.
>>
>> This looks like a much finner pitch than the units used
>> on the new car engines to drive the water pump and
>> alternator. I don't have any of those lying around.
>>
>> When I drew it I did not take the trouble to model
>> it exactly.
>>
>> Paul Lamar ...No rotor no motor.
>
> Machinist Handbook has them, I don't have a
> scanner, however I might be able to take a picture
> and send that. Not sure on the page either, but
> I'll look it up tomorrow.
>
> Jarrett
>
> I have Mac Hinnery's hand book.
>
> Here it is.
>
> Paul Lamar ...No rotor no motor.
Thank you
Ken
Ken, I think this is the web site you are looking for.
-------------------------
I take it back. That Gates web site sucks. Who ever heard
of having to register before you can download a pdf catalog.
The on line catalog is ridiculous as well. Sometimes these
people shoot them selves in the foot.
Here is a better one.
http://www.cptbelts.com/products/vribbed/vee_rib/index.html
You want a 3D DXF or a 2D DXF ?
Paul Lamar ...No rotor no motor.
------------------------------------------------
Paul,
Hutchinson is a good source of info for Poly V belts:
http://www.hutchinsontransmission.com/
They will mail you a design manual on request, which includes
detailed
tech info and a calculator for sizing.
Regards,
Gordon.
Thanks Gordon. I bought some cast iron pulleys from Mac Master but
I am not happy with them. The three inch pulley weighs 1.5 pounds
with QD bushing and has an RPM limit of 8340. The 4.5 " large one
weighs 2.75 pounds and has an RPM limit of 5560 making it marginal
for this application. See the chart for the design point. I think
I could do better if I found some steel sheet metal pulleys as
found on
most automotive engines these days. These are J section pulleys and
most automotive engines use the L section belts I suspect.
The L section however looks marginal as far as RPM is concerned for
the stock RX8 engine with a red line of 9,000 RPM.
This chart is probably rather conservative.
Paul Lamar ...No rotor no motor.
Paul,
If you go to the Hutchinson link I gave and click on "contacts"
you can
request the design manual and a list of distributors for pulleys. I
think both aluminum and steel are available and should go to
10,000 rpm.
The PJ section belt has a rib pitch of 2.34mm [.092"] and thickness
of 3.5mm [.138"], which sounds about right.
Incidentally, the design manual lists "ultralight aircraft" as one of
the application categories and I know Simonini 2-stroke UL engines
use
these belts, so no worries about having to fib about what you
intend to
use it for.
Regards,
Gordon.
Thanks again Gordon. What is interesting about these
belts is they are not really V-belts at all. There is no
wedging action going on. They are basically folded
up, guided flat belts with much more effective width than
a regular flat belt. The HP transmission capabilities are
stunning. What is old is new again :)
Paul Lamar
Paul,
Yeah these belts are really cool technology -- there is no wedging, just
friction. Some of the bigger ones are rated at over 1000hp, will take
high duty cycles, high rpm etc. and will last very long.
They also have great efficiency, 95 to 98 percent, which is as good or
better than cog belts, which wear out quickly. I really like these for a
prop reduction drive and I'm sure they will start catching on once
people clue into them.
Regards,
Gordon.
Guys,
I wouldn't get too excited about these belts until you look at the whole
picture. At high power levels and high rpm's the static belt tension
required is huge. To use them for a PSRU: the engine sheave couldn't
be cantilevered off the engine shaft, the four bearings required would
need forced lubrication, and a tensioning mechanism would be needed.
There are some benefits: the offset prop shaft would be useful for some
airframes, if belt tensioning is done with an idler it could be used to
drive an accessory. But, overall, I think it would be a challenge to
keep the weight low enough.
Aubrey
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