h a l f b a k e r yFlaky rehab
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Wind turbine speeding out of control? Or something else that spins and could spin
too fast? (I'm out of example ideas). Feedback loop not working and you need an
absolute final solution to a runaway rotation? A bearing built with an internal
structure that ejects a low-viscosity (and possibly
slowly thickening, like a 2-part
epoxy) at high speeds. Like a fuse protects electronic components, a fail-bearing
could protect valuable assets, slowing them down gradually and then solidifying.
One idea is to have fluid-filled cylinders that are hollow, filled with thickening agent
and capped with a cap that has a predetermined failure point, just like CO2 bottles
or SCUBA gear.
Wind turbine overspeed failures
https://youtu.be/No1Qzx1sQyc?t=40
Mentioned in my anno. What this idea is intended to prevent. Also, one of them just falls over while stopped. [notexactly, Mar 21 2019]
[link]
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// something else that spins and could spin too fast? (I'm out of
example ideas). // |
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Democratic party press officers ? |
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A child's concept in a finger painting? |
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When bearings fail, they often lock up and blow up
and break things. What you want is a clutch. Pretty
old technology. |
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but how to put a clutch in a bearing?... |
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//What you want is a clutch.// |
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My first thought was a standard style clutch, excess force
causes slip. The blades spin faster but the generator
becomes progressively decoupled. The problem there is
that the blades will spin up and self destruct, or, the
clutch will quickly suffer a fricton related heat problem...
quickly becoming an oxygen related fire problem. A
centrifugal clutch that engages a nice robust rotary
damper would be better. |
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Better still would be a centrifugal governor that feathers
the blades. But then how will you sell them a new one? |
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Easy - a dog-clutch, a spring, and a centrifugal governor. Spin the
assembly too fast, and the governor releases the spring.
Depending which way round the clutch is placed, either the drive
is allowed to freewheel from the load, or it engages to a brake or
fluid load to slow it. |
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Designing a part to do the opposite of it's intended job suggests the desired system is at fault. |
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Agreed. That's how we ended up with Republicans. |
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This idea is much more elegant than a clutch in many applications. Whenever you want to save the weight and complexity, but still have that last ditch stop. |
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It's like the fusible resistors used in cheap electronics,
primarily for current limiting but secondarily for emergency
overcurrent stopping. |
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//Designing a part to do the opposite of it's intended job
suggests the desired system is at fault.// |
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The key subverts the lock subverts the door subverts the
wall. |
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^ All parts are doing what is willed.They are doing their engineered jobs. To be pedantic, failure means to not act as wanted. This is a bearing designed not to bear under certain circumstances. |
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If we're just talking about wind turbines
, then rotating the vanes along their axis should
do the trick as it'd be the same wind speed on
both sides of the blade. |
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// fusible resistors used in cheap electronics // |
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Not just cheap electronics; very expensive electronjcs use them, too. |
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It seems appropriate to point out that all resistors are in fact fusible if subjected to sufficient overload. <snigger/> |
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// If we're just talking about wind turbines , then rotating
the vanes along their axis should do the trick as it'd be the
same wind speed on both sides of the blade. // |
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Feathering the blades? They do that. But they sometimes
have overspeed failures anyway: [link] |
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Has moving the blades forward been tried? -< . Less blade efficiency and balance is controlled by wind strength. Ultimately -- , shutdown. |
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The problem is energy dissipation. The rotating object
being born has both potential and apparently external
energy being applied. Stopping that requires absorbing
all the energy without damage. Absorbing energy
without releasing it leads to build ups of energy (usually
in the form of heat) which are nearly always going to
result in damage. If the object doing the absorbing is on
the outside, it can radiate the energy away, but on the
inside? No, what happens here is the bearing or the shaft
it is bearing overheat and melt. Now you have a spinning
load that is no longer born. That's worse. A clutch at the
end of the shaft, or a brake outside the shaft is the way
to go. |
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// Designing a part to do the opposite of it's intended job suggests the desired system is at fault. // |
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Easily solved by marketing it instead as a Success Bearing. When the shaft turns too fast, the bearing succeeds (at stopping it). |
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