Design limits of electric motors?

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Hate to burst your bubble, but they *do* make gearing for this kind of power. Typical steamships use reduction gears between the IP/LP turbines (in thousands of RPM) and the main shaft (hundreds of RPM). And smaller gearing between the HP and IP turbines. Bull-gears, the final output gear connected to the propeller shaft are large with double helix cut. Often use double-reduction with 'quill' shafts between successive gear stages.
Saw more than one bull gear get some broken teeth ground out. Didn't replace the teeth, just ground down the sharp edges so they wouldn't wear into the low-speed pinions (some sailors didn't believe the rules about FOD). Some marine applications include clutches that can carry over 35000 hp. These ain't your standard automobile clutch, they have dozens of friction plates and positive, splined-sleeve engagement.
Large stationary power plants have the HP and LP turbines co-linear with the generator, that is true. But the 'shaft' is made up of several pieces, one for each turbine section and another for the generator. Each section is bolted to the next with flat-faced, bolted couplings. One plant (I think in Korea) a year or so back had a failure where a fire in one bearing support caused it to sieze. The shaft twisted right apart and in the process threw pieces/parts all around the turbine building. The pictures were *very* impressive.
Get a couple of mechanical engineers together in a room and they can come up with things almost as outlandish and exotic as any EE's :-)
daestrom
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up
And from the EE side we have the Rabbit phone For the mechanics we have the Edsel.
And as proof that the engineers can get it right but still not succeed there is of course Betamax.
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Nothing wrong with the electronics in a Rabbit phone was there? Perhaps there was, but that's not why it failed. It was just a crap idea. So now they're doing it again with Wi-Fi hotspots.
Tim
--
Love is a travelator.

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On Tue, 08 Jun 2004 21:03:37 GMT, "daestrom"

There was a gear being ground at DeLaval for a LASH ship, and the grinder operator guy set the final grind pass to 10 mils instead of 1 mil. So this 32 foot diameter double-helix million-buck gear came out with square edges on all the teeth. They called the shipyard (Avondale), told them the gear would be a few weeks late, and gave the guy a file. True story.
John
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message wrote:

gear
use
I believe it. When you screw up something *that* big and expensive, they find a way to make it work anyway ;-)
daestrom
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On Tue, 08 Jun 2004 21:03:37 GMT, "daestrom"

On the ships I saw, the access ports to the main gear were sealed with huge padlocks, and only the Chief had the keys. The gears are just too tempting a tagret for sabatoge.
John
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message wrote:

gear
use
Yep. But when the sailor has a preventative maintenance procedure to go in and take some measurements, if they aren't careful about restraining all the things about their person, some genuine accidents do happen. And if the sailor is too scared of the 'chief' to admit anything, then it gets left inside. Eventually, with the motion of the ship and all, it gets ground up in the gear. Leaving some damaged teeth behind.
daestrom
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On Wed, 09 Jun 2004 20:38:45 GMT, "daestrom"

So they should just use pulleys and belts.
John
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta content="text/html;charset=UTF-7" http-equiv="Content-Type"> <title></title> </head> <body bgcolor="+ACM-ffffff" text="+ACM-000000"> daestrom wrote:<br> <blockquote cite="midpzKxc.63893+ACQ-j24.24493+AEA-twister.nyroc.rr.com" type="cite"> <pre wrap="">"John Larkin" <a class="moz-txt-link-rfc2396E" href="mailto:jjlarkin+AEA-highlandSNIPtechTHISnologyPLEASE.com">+ACY-lt;jjlarkin+AEA-highlandSNIPtechTHISnologyPLEASE.com+ACY-gt;</a> wrote in message <a class="moz-txt-link-freetext" href="news:jkaec0tu69q5o3jsj9ijm0edpr4a95dl3u+AEA-4ax.com">news:jkaec0tu69q5o3jsj9ijm0edpr4a95dl3u+AEA-4ax.com</a>... </pre> <blockquote type="cite"> <pre wrap="">On Tue, 08 Jun 2004 21:03:37 GMT, "daestrom" <a class="moz-txt-link-rfc2396E" href="mailto:daestrom+AEA-NO+AF8-SPAM+AF8-HEREtwcny.rr.com">+ACY-lt;daestrom+AEA-NO+AF8-SPAM+AF8-HEREtwcny.rr.com+ACY-gt;</a> wrote:
</pre> <blockquote type="cite"> <pre wrap="">Hate to burst your bubble, but they +ACo-do+ACo- make gearing for this kind of power. Typical steamships use reduction gears between the IP/LP turbines (in thousands of RPM) and the main shaft (hundreds of RPM). And smaller gearing between the HP and IP turbines. Bull-gears, the final output </pre> </blockquote> </blockquote> <pre wrap=""><!---->gear </pre> <blockquote type="cite"> <blockquote type="cite"> <pre wrap="">connected to the propeller shaft are large with double helix cut. Often </pre> </blockquote> </blockquote> <pre wrap=""><!---->use </pre> <blockquote type="cite"> <blockquote type="cite"> <pre wrap="">double-reduction with 'quill' shafts between successive gear stages.
Saw more than one bull gear get some broken teeth ground out. Didn't replace the teeth, just ground down the sharp edges so they wouldn't wear into the low-speed pinions (some sailors didn't believe the rules about FOD). </pre> </blockquote> <pre wrap="">On the ships I saw, the access ports to the main gear were sealed with huge padlocks, and only the Chief had the keys. The gears are just too tempting a tagret for sabatoge. </pre> </blockquote> <pre wrap=""><!----> Yep. But when the sailor has a preventative maintenance procedure to go in and take some measurements, if they aren't careful about restraining all the things about their person, some genuine accidents do happen. And if the sailor is too scared of the 'chief' to admit anything, then it gets left inside. Eventually, with the motion of the ship and all, it gets ground up in the gear. Leaving some damaged teeth behind.
daestrom
</pre> </blockquote> <tt>In the US Navy I was in, ships reduction gears where not opened except for very<br> carefully planned evolutions.+AKA- All tools/parts/rags/etc. were logged in and logged<br> back out of a "clean" area around any open reduction gear cover. Any time a cover <br> was open an armed guard was placed on it to prevent any/all possibility of damage<br> to the gear. Opening up an red. gear was/is a very rare evolution and is usually<br> watched closely by the Engineer Officer, the M division officer, and possibly the<br> ships' Captain.<br> In addition, the lube oil low pressure alarm for the reduction gear energized a <br> siren that could wake up the dead two area codes away, just to give an indication<br> serious even the possibility of damage to the gear is considered.<br> It was easier for two missile techs to do PMs on a Polaris missile than it was to<br> get permission to open an inspection cover on the boats' reduction gear.<br> ARM<br> <br> <br> ARM<br> <br> </tt> </body> </html>
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daestrom wrote:
<Snipped unreadable html crap>
How light yellow on while background or perhaps even dark brown on black?
SioL
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that was horrible! shame on you :(
Legible Cheers, Terry
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+ACY-lt;jjlarkin+AEA-highlandSNIPtechTHISnologyPLEASE.com+ACY-gt; wrote in

kind of

with
in
the
up
for very

in and logged

a cover

damage
usually
possibly the

energized a

indication
was to

Yep, the same as my US Navy. But the lower-level watch changes the main lube-oil strainer once a watch. Care to guess what sort of things can be dropped into a strainer housing while the strainer is removed? Even just buttons off your sleeve or a pair of dolphins off your shirt. Not always deliberate, but lets face it, it happens. And the gears chew em up and grind em to bits. But that leaves a mark on the gear.
Ditto for the lube oil sump when its open for inspection/cleaning. The close-out of the sump is signed off by an officer. Some junior officers don't bother to leave the ward-room to perform that inspection.
Navy has been using FOD (Foreign Object Damage) prevention practices for a long time. Yes, the engineer has the key to the locks on the reduction gear and the sailors setup a tent over the gear and go through a lot to put lanyards on all tools, and log everything in and out. But guess what, sh** still happens.
daestrom
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daestrom wrote:

Second try. Sorry about the HTML, Mozilla and I haven't come to terms yet. ARM
In the US Navy I was in, ships reduction gears where not opened except for very carefully planned evolutions.+ACs-AKA- All tools/parts/rags/etc. were logged in and logged back out of a "clean" area around any open reduction gear cover. Any time a cover was open an armed guard was placed on it to prevent any/all possibility of damage to the gear. Opening up an red. gear was/is a very rare evolution and is usually watched closely by the Engineer Officer, the M division officer, and possibly the ships' Captain. In addition, the lube oil low pressure alarm for the reduction gear energized a siren that could wake up the dead two area codes away, just to give an indication serious even the possibility of damage to the gear is considered. It was easier for two missile techs to do PMs on a Polaris missile than it was to get permission to open an inspection cover on the boats' reduction gear. ARM
ARM
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wrote:

turbines
smaller
Often
wear
in
the
up
Depends on the situation I guess. IMA and 'depot' level maintenance opens them up fairly routinely. But like I mentioned in my other post, the lube oil system isn't so tightly controlled. The strainer is swapped every watch by 'lower-level louie'. And when the sump is opened up for clean/inspect, it is usually some junior officer that does the close-out inpsection (not a very easy job to do).
Small crap *does* get in them despite all the precautions. Doesn't put a gear OOC, but does leave its 'mark' on things. Buttons, 2nd-class metal 'crow' insignia, dolphins, 'tweakers', you name it. Some identifiable remains, some just bits of plastic/metal.
daestrom

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John Larkin wrote:

sabotage - the word has an interesting etymology.
A "sabot" is a wooden shoe, so named by the French peasants who wore them. We know them as clogs, and tend to associate them more with the Dutch. Anyhow... during the Industrial Revolution, "saboteurs" became so-called from their practise of throwing a sabot into the gears of the machinery, thereby "clogging up the works" and often breaking the gears.
Irrelevant to electronics, but the kind of thing that geeks and engineers like to know :-).
Clifford Heath.
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On Thu, 10 Jun 2004 10:46:03 +1000, Clifford Heath

Isn't a sabot also the drop-away casing used on those hypervelocity uranium tank-killer shells?
John
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John Larkin wrote:

APDS (I think) = Armor-Piercing Discarding-Sabot rounds are kinetic-energy killers. The penetrator is necessarily a dense material, usually either depleted uranium or tungsten. Note that shot-guns may also use sabots for flechetes. I guess one could think of the patch around a musket ball as a sabot too. ;-)
--
Keith

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...
Yep, but surely most proper geeks and engineers would have learned it from Star Trek... uh... VI, I think it was? :-)
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wrote:

Yes, "The Undiscovered Country". When coming up with an excuse why the Enterprise could not return to base as ordered, the young female Vulcan explains the Dutch history of the word.
daestrom P.S. And yes, a 'sabot' is also a drop-away casing around irregularly shaped objects used to make them fit in a gun barrel.
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daestrom wrote:

IIRC, sabotage, saboteur and the like come from the french word for wooden shoe. In the early days of industrialisation these shoes were dropped into the maschines by workers when they wanted a rest. The shoes would jam somewhere and stop the maschine.
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