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DanH

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How about a Fluid Damper designed for Diesel trucks.
The only unanswered is what is the maximum RPM?
Designed, machined, and flew a silicone filled viscous disc damper in late 1999. Grand Champion Lightplane at Sun n' Fun 2000, but I doubt the judges had a clue about the blue anodized cover on the face of the flywheel.
It was a real damper, able to absorb something like 90 times more heat energy than the Centaflex with which it was paralleled.

Not quite the same principle as the Fluid damper. Later I did find a Borg Warner patent for a very similar device intended to be installed parallel to the clutch springs in HD trucks.
 
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PMD

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How do you delete a post in this forum?
Hit the "report" button on the lower left of your post and I assume that will go to a moderator's message box. Mod will do what you ask (if possible...er...related to the site. There are no doubt many other things they will NOT do for us.
 

wsimpso1

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How do you delete a post in this forum?
Members can edit their own posts for about 24 hours. Once that time is up, you can report it to the moderators asking for deletion. We have some fundamental objections to being "the editor":
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In short, do your own editing prior to posting.

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BJC

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Everyone of us is responsible for what we write. If we might not LOVE our post in perpetuity, maybe we let it cool on our computer for a few hours. Edit there, maybe delete the whole thing. But do not post it unless you are ready for it to have legs;
Back when I was working for a living, I wrote many letters and memos that I put in my desk drawer rather than sending them. Took them out and read then the next morning. Almost all made me blush as I tore them up and trashed them.


BJC
 

DanH

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Took them out and read then the next morning. Almost all made me blush as I tore them up and trashed them.

Nothing like that. I just clicked reply rather than edit, so the result was a lightly edited double post.
 

DanH

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Continuing the theme...all "giubos" are not the same...

Take a look at the three examples pictured below. One is a OEM automotive drivetrain part. The other two are primarily intended to tailor torsional behavior. What is the significant difference?

What, no takers? Where are all the giubo experts?
 
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What, no takers? Where are all the giubo experts?
Far from an expert but I like to figure things out.

A) Can't tell from the pic but it may have no provision for angular misalignment? Radial pins look like a poor way to transfer torque.
B) Has asymmetrical rates and needs to be phased for the primary load?
C) Symmetrical loading but needs to be installed in a pre-compressed condition for proper spring rate?

Some of the auto units (B) do get compressed during installation. They just don't come pre-compressed with the band.
 

DanH

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Radial pins look like a poor way to transfer torque.

Not at all. Although the axial sockets can run on pins, the Centaflex radial connection is always clamped with bolts.

B) Has asymmetrical rates and needs to be phased for the primary load?

Some of the driveshaft couplers are indeed asymmetrical, with different stiffness for each direction of rotation. That different stiffness is commonly due to internal cord windings (illustration attached). Symmetrical or asymmetrical, these driveline couplers (1) tend to be a lot stiffer, and as an operating principle, (2) transmit torque almost entirely via tension member, not rubber in compression, thus the lower proportional damping rate.

C) Symmetrical loading but needs to be installed in a pre-compressed condition for proper spring rate?
Some of the auto units (B) do get compressed during installation. They just don't come pre-compressed with the band.

Very good sir. Couplers without internal tension cords transmit most of the torque via rubber in compression. In addition, no cord members mean they can tolerate much larger angular, radial, and axial misalignments. Pre-compression during installation further increases life, because the rubber on the tension side of a load is largely relaxed rather than stretched.

Returning to those radial bolts in the Centaflex A, they provide far more ways to connected driving and driven members, and they pre-compress the rubber element when tightened, no hassle, no bands.
 

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DanH

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But the Centaflex looks pretty rigid, as if it's designed to primarily handle slight shaft misalignment. The other two look like the 'soft' parts are designed to be more soft & 'springy'. (Serious high level engineering terms)
Ding, ding....no to both ;)

But it does nicely illustrate the key concept...you can't pick couplers by looking at them, or just grabbing some random "giubo".
 

DanH

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May 20, 2019
Messages
140
Previously I wrote...

Centaflex is a bit fuzzy on that point. I've attached their explanation below.

I just send an information request to Centa.

...the question being a better definition of Pkv, Permissible Power Loss.

The answer, from a fellow identifying himself as as application engineer in the US office, was basically "I dunno". I started to send a response suggesting he might contact a colleague at Centa in Germany, but then I got thinking about it. Duh.

A watt = one joule per second. A joule is a unit of energy, so Pkv is apparently the manufacturer's stated maximum amount of energy per second which can be lost to damping without damaging the coupler.
 
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