[SEL] Curved spokes ...engine rotation

[Clint D]

Steve

make sure you use a left and right handed sledge! thats is to make sure 
you get the correct tones :-)
Clint


Steve Royster wrote:

> I'm going to go home tonight and get a big sledge hammer and "test" 
> the spokes on all my engines! Thank you Rob for sharing this 
> information for the safety of the SEL!  Steve Royster
>
>
>> From: "Rob Skinner" <rskinner at rustyiron.com>
>> Reply-To: The SEL email discussion list 
>> <sel at lists.stationary-engine.com>
>> To: "'The SEL email discussion list'" <sel at lists.stationary-engine.com>
>> Subject: RE: [SEL] Curved spokes ...engine rotation
>> Date: Wed, 24 May 2006 08:47:25 -0700
>>
>>
>> >If the flywheel runs the opposite way the outer
>> > rim will tend to wan't to fold in on itself.
>>
>> Right you are, Lindsay.  Renowned engine builder Sheldon
>> Brown, partner of Jeremiah Cochran, studied the issue in
>> great detail.  Here is what he wrote in his Famous Flywheel
>> Treatise of 1904:
>>
>> Are your flywheels spoked right, or are they giving you
>> trouble?
>> Many engineers would answer with a rueful "Right!"
>>
>> Spoke Cracking Leads to Flywheel Breakage!
>> Thanks to superior American technology, modern engines are
>> more powerful than ever. At the same time, the trend to
>> lighter flywheels and fewer spokes continues.
>>
>> As a result of the higher stresses and cutting-edge
>> construction, a fundamental design flaw in existing
>> flywheels comes to light. Millions of engines are suffering
>> cracked or broken spokes usually on the left side flywheel,
>> leading to poor fuel economy at best, or getting left behind
>> by your competition, or, in more severe cases, injury or
>> death!
>>
>> Older flywheels were so over-built that they made up for
>> incompetent design by having lots of heavy curved spokes and
>> heavier-than-necessary rims. Even today, most right side
>> flywheels hold up alright, because they still have more
>> spokes than are needed to cope with the usual loads
>> experienced by flywheels...but what about the all-important
>> left flywheel?
>>
>> While the right side spokes tend to hold up alright, the
>> left spokes are often left with insufficient strength. If a
>> left spoke is cracked, there's no way that the engine can
>> run right...you'll suffer catastrophic flywheel breakage due
>> to metal fatigue on the left spokes.
>>
>> Go right now to wherever you left your engine, and check the
>> spoke tension of your right wheel by plinking the spokes
>> with a sledge hammer and listening to the tone. You'll
>> probably find that the right side spokes are at the right
>> tone, but that the left spokes will be less melodious. When
>> you plunk the left spokes you'll notice that the pitch of
>> the plunk is considerably lower than that of the right
>> spokes. Why is this?
>>
>> The Myth of "Bent Spokes"
>> Believe it or not, many of the unscrupulous con-artists that
>> are so common in the engine industry will try to get you to
>> believe that this is a "feature!" Yeah, right!
>>
>> They'll give you some spiel about a mystical property called
>> "curve", which supposedly has something to do with the fact
>> that the belt is on the right side. This is, of course,
>> complete nonsense, since the belt never touches the
>> flywheel, as long as your machinery is aligned just right.
>>
>> History Lesson Part 1.
>> These idiots must have been left back in school when it was
>> time to study history. Everybody knows that in the early
>> days of engines, there was a problem with the left flywheels
>> falling off.
>>
>> This was solved by the Wright brothers, when they invented
>> the system of using a left-hand thread on the left flywheel
>> bolt.
>>
>> Precession
>> You might think that this would not be right, and that the
>> Wright brothers had it backwards, because the friction of
>> the main bearings would tend to turn the right flywheel to
>> the left and the left flywheel to the right. Thus, the
>> right-handed right flywheel should fall right off, while the
>> left handed left flywheel would be left in place...but it
>> doesn't work that way; instead an interaction with the
>> Earth's magnetic field sets up eddy currents right in side
>> the crankshaft, leading to a tendency for the flywheels to
>> tighten themselves, as if by magic.
>>
>> History Lesson Part 2.
>> When Nicolas Otto and Tullio Crossley independently invented
>> the engine, back in the olden times, they used normal
>> right-handed threading for the crankshaft main bearing caps.
>> This worked alright for the left caps, but it was discovered
>> that the right cap would tend to unscrew itself in use,
>> unless the engine was left out in the rain, where rust could
>> help to immobilize the threads.
>>
>> The great British engine inventor Dugald Clerk cured this
>> problem by making the right crankshaft main bearing cap have
>> left-hand threads, so that, even if it starts a little bit
>> loose, it will tighten itself right up.
>>
>> The French were slow to pick up on this improved technique,
>> and many German engines are still made with wrong-way
>> threading, but the rest of the world has picked up on this,
>> and the vast majority of engines now have main bearing caps
>> that are threaded the right way: right threads on the left
>> side, left threads on the right side.
>>
>> The Lessons of History
>> Like many great inventions, bilateral obverse threading
>> seems completely obvious once it has been explained; the
>> solution to the problem of left flywheel breakage is, in
>> fact just a simple matter of using a left-hand threading on
>> the clamps that run to the left side of the flywheel!
>>
>> This completely eliminates the precession effect that tends
>> to loosen left side flywheels in old-fashioned engines that
>> use right-hand threading!
>>
>> Flywheel Building Issues
>> Since I'm a practical mechanic as well as an inventor, I
>> couldn't overlook the confusion that having two different
>> types of bolts could cause. I've come up with an ingenious
>> solution to the problem, however:
>>
>> As an optional accessory item to bilateral obverse thread
>> systems, we are making available special color-coded bolts
>> to help the engine builder keep track of which is which.
>> Since left hand bolts look just like ordinary bolts, we
>> offer special bright red bolts to fit the right-hand
>> threaded spokes still used on the right side of the wheel.
>> This prevents them from becoming confused with the left-hand
>> threaded bolts.
>>
>> What About the Southern Hemisphere?
>> Well, what about it? It is well known that in the Southern
>> hemisphere, the problem of left flywheels loosening up does
>> not occur, but rather it is the right flywheels that loosen
>> up if left to their own devices.
>>
>> Hence, engineers who run engines mainly in the Southern
>> hemisphere should use left hand threads on the right side
>> flywheels, not the left.
>>
>> Honesty compels me to admit that for engineers who live and
>> run engines within 50 miles of the Equator, any bolts will
>> offer little functional value.
>>
>> Engineers who regularly travel back and forth between the
>> Northern and Southern hemispheres would be well advised to
>> swap the flywheel bolts side-to-side after crossing the
>> equator.
>>
>>
>>
>>
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