Energy FAQ

Question:

Try wrapping black straps around it and hooking the ends ,,, black rubber – like truck drivers use … M.M. – Hide quoted text — Show quoted text ->I learned something interesting today. My generator makes low pitched > knocking noises from the cylinders, but also some high pitched noise. > To my great surprise, that high pitched noise was mostly coming from > the "bell" cover of the generator head. As soon as I placed both of my > hands on it firmly, the generator instantly became considerably > quieter. The difference was amazing. > My first question is, how come it makes so much noise. It did not > feel as though some moving part was touching it from inside. > My second question is, can I find some material and applicator > (adhesive or magnetic) to attach an equivalent of a human palm, for > vibration control purposes. I am thinking about the silicone "boob" > material, like from better mousepads, or pads for keyboards, on some > advesive backing. > I could buy such silicone boob from say a computer store and attach it > with electrical tape. i would prefer something more professional, if > it would not cost too much. Just how much can such things set me back > and where to find them? I believe I could go quite a long way by > applying vibration dampeners to a few steel plates. Won’t do much for > the low noise, but it is not as annoying as high pitched noise. >In the submarine world, vibration dampening was *the* thing.  Being quieter >than the soviets was paramount.  Sounds like what you have there is a cover >that is resonating from some excitation vibration in the engine or >generator.  Easiest way to dampen something like that is to add weight.  Get >yourself something like a hose clamp that can go completely around the bell >housing with some room to spare.  Then evenly space some small bolts under >the clamp.  About eight or ten should be enough.  Tighten the clamp down >good so the bolts and bell housing vibrate as one.  This should change the >resonant frequency of the bell enough that it stops vibrating.  If I had a >nickel for each of the ‘anti-vibration staves’ I’ve strapped onto ’singing’ >pipes, I’d be on easy street. >Putting your hands on it works because you’re actually adding two things. >Another mass, and a viscous damper between the primary mass (the bell >housing) and the secondary mass (your hand). >daestrom

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> My second question is, can I find some material and applicator > (adhesive or magnetic) to attach an equivalent of a human palm, for > vibration control purposes. I am thinking about the silicone "boob" > material, like from better mousepads, or pads for keyboards, on some > advesive backing.

Why go synthetic? Harley Davidson vibration is dampened by LIVE models, sporting what may or not be silicone ‘boob’ material. They usually place their hands on the tank just ..so.. Replace gas tank with bell housing and you’ve got yourself a pin up shot for all sorts of Diesel Fanatic calendars. A thin coat of bio-diesel on the models give a lustrous sheen that is so desirable in alternative energy circles. Adhesive backing would certainly make sure the ‘dampers’ don’t leave work too early. mike

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I have read some great suggestions here. Some of them, or all of them, might work. An easier solution might be already out there for you. If you go to an automotive repair store, you will find that they sell a harmonic dampening silicone to be applied to the back of disc-brake pads. (disc breaks can produce a great laud screech when they are applied.) When they replace pads, they either come with a harmonic suppressor pad, or they use the silicone to coat the pad before installation. I’d suggest you smear this stuff all over it. It might help suppress the harmonic sound you are getting, and it should hold up to any temperatures it might get (it is designed to be on the back of disc pads…. they can get REAL hot in normal operation) Good luck, Hope you can find some peace and quiet

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I noticed the problem you had in an earlier post. I replied with the following and this came close ! In case you had not read it here it is again.. I have read some great suggestions here. Some of them, or all of them, might work. An easier solution might be already out there for you. If you go to an automotive repair store, you will find that they sell a harmonic dampening silicone to be applied to the back of disc-brake pads. (disc breaks can produce a great laud screech when they are applied.) When they replace pads, they either come with a harmonic suppressor pad, or they use the silicone to coat the pad before installation. I’d suggest you smear this stuff all over it. It might help suppress the harmonic sound you are getting, and it should hold up to any temperatures it might get (it is designed to be on the back of disc pads…. they can get REAL hot in normal operation) Good luck, Hope you can find some peace and quiet Dave… remove the urine in email address to get me…

– Hide quoted text — Show quoted text -> Semi jokingly, I found this "JAC OFF" silicone pad that should be > working. It is just like my hand, after all. > http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=5545417145 > Will look for something more rectangular though. > i > I learned something interesting today. My generator makes low pitched > knocking noises from the cylinders, but also some high pitched noise. > To my great surprise, that high pitched noise was mostly coming from > the "bell" cover of the generator head. As soon as I placed both of my > hands on it firmly, the generator instantly became considerably > quieter. The difference was amazing. > My first question is, how come it makes so much noise. It did not > feel as though some moving part was touching it from inside. > My second question is, can I find some material and applicator > (adhesive or magnetic) to attach an equivalent of a human palm, for > vibration control purposes. I am thinking about the silicone "boob" > material, like from better mousepads, or pads for keyboards, on some > advesive backing. > I could buy such silicone boob from say a computer store and attach it > with electrical tape. i would prefer something more professional, if > it would not cost too much. Just how much can such things set me back > and where to find them? I believe I could go quite a long way by > applying vibration dampeners to a few steel plates. Won’t do much for > the low noise, but it is not as annoying as high pitched noise. > i > —

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Yeah, something is resonating.  Could be that you have found the natural frequency of the bell cover, which is being excited by the engine firing. (The firing event is "broad band" in frequency during each occurance even though the "firing frequency" itself is low). As Ron said, The easiest solution is probably to add mass.  Look under just about any new Dodge Truck or Jeep at the rear axle and you will see a mass hanging off of it which is sometimes referred to as "donkey balls".  Acutally these have a rubber mount as well which gives them some degree of behavior as a tuned absorber.  Tuning absorbers is hell if you don’t have the right equipment. When adding the mass try not to mount it at just one point.  It may happen that you create a prime location for fatigue failure if all of the reaction of the mass vibration travells through just one point. Rory Johnson – Hide quoted text — Show quoted text ->To my great surprise, that high pitched noise was mostly coming from >the "bell" cover of the generator head. As soon as I placed both of my >hands on it firmly, the generator instantly became considerably >quieter. The difference was amazing. > The cover’s resonant frequency happens to match something else > that’s vibrating. Three solutions, from easiest to hardest: > 1: Add some mass. Sometimes just sticking some heavy magnets to > it will help. > 2: Make it stiffer. Often easier said than done, but might be > worth a try. > 3: Add a "dynamic absorber" (tuned mass/spring system) that > vibrates out of phase at the same frequency, cancelling the > vibration. This involves some trial and error but can work well > in some cases. The classic paper on dynamic absorbers is here: > http://domino.automation.rockwell.com/applications/gs/region/EntekWeb… > (PDF file, watch line wrap) > If the paper is not there, look for a paper by Randy Fox on this page: > http://domino.automation.rockwell.com/applications/gs/region/EntekWeb… > I don’t think the consistency of the material makes any > difference, except to the extent that it’s also making it heavier > and/or stiffer. Lead weights should work just as well. > Of course it would be nice to find the driving force behind the > vibration and correct it (ie, make the machine run smoother in > the first place), but if the resonant frequency of the cover matches > the speed the generator has to run at, it may vibrate anyway. > So you’re back to changing its mass and/or stiffness.

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- Hide quoted text — Show quoted text ->I learned something interesting today. My generator makes low pitched > knocking noises from the cylinders, but also some high pitched noise. > To my great surprise, that high pitched noise was mostly coming from > the "bell" cover of the generator head. As soon as I placed both of my > hands on it firmly, the generator instantly became considerably > quieter. The difference was amazing. > My first question is, how come it makes so much noise. It did not > feel as though some moving part was touching it from inside. > My second question is, can I find some material and applicator > (adhesive or magnetic) to attach an equivalent of a human palm, for > vibration control purposes. I am thinking about the silicone "boob" > material, like from better mousepads, or pads for keyboards, on some > advesive backing. > I could buy such silicone boob from say a computer store and attach it > with electrical tape. i would prefer something more professional, if > it would not cost too much. Just how much can such things set me back > and where to find them? I believe I could go quite a long way by > applying vibration dampeners to a few steel plates. Won’t do much for > the low noise, but it is not as annoying as high pitched noise. > In the submarine world, vibration dampening was *the* thing.  Being quieter > than the soviets was paramount.  Sounds like what you have there is a cover > that is resonating from some excitation vibration in the engine or > generator.  Easiest way to dampen something like that is to add weight.  Get > yourself something like a hose clamp that can go completely around the bell > housing with some room to spare.  Then evenly space some small bolts under > the clamp.  About eight or ten should be enough.  Tighten the clamp down > good so the bolts and bell housing vibrate as one.  This should change the > resonant frequency of the bell enough that it stops vibrating.  If I had a > nickel for each of the ‘anti-vibration staves’ I’ve strapped onto ’singing’ > pipes, I’d be on easy street.

This makes complete sense. I will try to combine adding weight, with damoening action. Ibought some silicone gel thingy on ebay and will strap it to the housing with electrical tape. I hope to receive the decibel meter by then and will report the result. > Putting your hands on it works because you’re actually adding two things. > Another mass, and a viscous damper between the primary mass (the bell > housing) and the secondary mass (your hand).

I tend to agree with this. I may also go to walmart and buy some silicone bra inserts and tape them to various stamped sheet pieces of the genset. i

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– Hide quoted text — Show quoted text ->I learned something interesting today. My generator makes low pitched > knocking noises from the cylinders, but also some high pitched noise. > To my great surprise, that high pitched noise was mostly coming from > the "bell" cover of the generator head. As soon as I placed both of my > hands on it firmly, the generator instantly became considerably > quieter. The difference was amazing. > My first question is, how come it makes so much noise. It did not > feel as though some moving part was touching it from inside. > My second question is, can I find some material and applicator > (adhesive or magnetic) to attach an equivalent of a human palm, for > vibration control purposes. I am thinking about the silicone "boob" > material, like from better mousepads, or pads for keyboards, on some > advesive backing. > I could buy such silicone boob from say a computer store and attach it > with electrical tape. i would prefer something more professional, if > it would not cost too much. Just how much can such things set me back > and where to find them? I believe I could go quite a long way by > applying vibration dampeners to a few steel plates. Won’t do much for > the low noise, but it is not as annoying as high pitched noise.

In the submarine world, vibration dampening was *the* thing.  Being quieter than the soviets was paramount.  Sounds like what you have there is a cover that is resonating from some excitation vibration in the engine or generator.  Easiest way to dampen something like that is to add weight.  Get yourself something like a hose clamp that can go completely around the bell housing with some room to spare.  Then evenly space some small bolts under the clamp.  About eight or ten should be enough.  Tighten the clamp down good so the bolts and bell housing vibrate as one.  This should change the resonant frequency of the bell enough that it stops vibrating.  If I had a nickel for each of the ‘anti-vibration staves’ I’ve strapped onto ’singing’ pipes, I’d be on easy street. Putting your hands on it works because you’re actually adding two things. Another mass, and a viscous damper between the primary mass (the bell housing) and the secondary mass (your hand). daestrom

Response:

– Hide quoted text — Show quoted text -> I learned something interesting today. My generator makes low pitched > knocking noises from the cylinders, but also some high pitched noise. > To my great surprise, that high pitched noise was mostly coming from > the "bell" cover of the generator head. As soon as I placed both of my > hands on it firmly, the generator instantly became considerably > quieter. The difference was amazing. > My first question is, how come it makes so much noise. It did not > feel as though some moving part was touching it from inside. > My second question is, can I find some material and applicator > (adhesive or magnetic) to attach an equivalent of a human palm, for > vibration control purposes. I am thinking about the silicone "boob" > material, like from better mousepads, or pads for keyboards, on some > advesive backing.

There is a material known as "composite steel", which consists of sheets of steel that have been pounded together, ala the Damascene sword. This steel is inherently vibration absorbing, and is used for acoustic control. You might consider tack welding pieces of it to the bell cover. This would be more durable under exposure to vibration, temperature, and fuel leakage, than plastics.

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>To my great surprise, that high pitched noise was mostly coming from >the "bell" cover of the generator head. As soon as I placed both of my >hands on it firmly, the generator instantly became considerably >quieter. The difference was amazing.

The cover’s resonant frequency happens to match something else that’s vibrating. Three solutions, from easiest to hardest: 1: Add some mass. Sometimes just sticking some heavy magnets to it will help. 2: Make it stiffer. Often easier said than done, but might be worth a try. 3: Add a "dynamic absorber" (tuned mass/spring system) that vibrates out of phase at the same frequency, cancelling the vibration. This involves some trial and error but can work well in some cases. The classic paper on dynamic absorbers is here: http://domino.automation.rockwell.com/applications/gs/region/EntekWeb… (PDF file, watch line wrap) If the paper is not there, look for a paper by Randy Fox on this page: http://domino.automation.rockwell.com/applications/gs/region/EntekWeb… I don’t think the consistency of the material makes any difference, except to the extent that it’s also making it heavier and/or stiffer. Lead weights should work just as well. Of course it would be nice to find the driving force behind the vibration and correct it (ie, make the machine run smoother in the first place), but if the resonant frequency of the cover matches the speed the generator has to run at, it may vibrate anyway. So you’re back to changing its mass and/or stiffness.

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- Hide quoted text — Show quoted text ->>To my great surprise, that high pitched noise was mostly coming from >>the "bell" cover of the generator head. As soon as I placed both of my >>hands on it firmly, the generator instantly became considerably >>quieter. The difference was amazing. >The cover’s resonant frequency happens to match something else >that’s vibrating. Three solutions, from easiest to hardest: >1: Add some mass. Sometimes just sticking some heavy magnets to >it will help. >2: Make it stiffer. Often easier said than done, but might be >worth a try. >3: Add a "dynamic absorber" (tuned mass/spring system) that >vibrates out of phase at the same frequency, cancelling the >vibration. This involves some trial and error but can work well >in some cases. The classic paper on dynamic absorbers is here: >http://domino.automation.rockwell.com/applications/gs/region/EntekWeb… >(PDF file, watch line wrap) >If the paper is not there, look for a paper by Randy Fox on this page: >http://domino.automation.rockwell.com/applications/gs/region/EntekWeb… >I don’t think the consistency of the material makes any >difference, except to the extent that it’s also making it heavier >and/or stiffer. Lead weights should work just as well. >Of course it would be nice to find the driving force behind the >vibration and correct it (ie, make the machine run smoother in >the first place), but if the resonant frequency of the cover matches >the speed the generator has to run at, it may vibrate anyway. >So you’re back to changing its mass and/or stiffness. > or adding an equivaent of my hand, something soft and dampening. > Thanks for the pointers. I thought I had a silicone computer pad lying > around, but I am not so sure now. > i

How does the cover mount? Can you put a soft gasket under it? How about a shim someplace. Sometimes a "hammer adjustment" will help, a small crease in the cover may stop the vibration. Dave

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I think the word you are looking for is "resonance". Steve Spence Dir., Green Trust http://www.green-trust.org – Hide quoted text — Show quoted text – > I learned something interesting today. My generator makes low pitched > knocking noises from the cylinders, but also some high pitched noise. > To my great surprise, that high pitched noise was mostly coming from > the "bell" cover of the generator head. As soon as I placed both of my > hands on it firmly, the generator instantly became considerably > quieter. The difference was amazing. > My first question is, how come it makes so much noise. It did not > feel as though some moving part was touching it from inside. > My second question is, can I find some material and applicator > (adhesive or magnetic) to attach an equivalent of a human palm, for > vibration control purposes. I am thinking about the silicone "boob" > material, like from better mousepads, or pads for keyboards, on some > advesive backing. > I could buy such silicone boob from say a computer store and attach it > with electrical tape. i would prefer something more professional, if > it would not cost too much. Just how much can such things set me back > and where to find them? I believe I could go quite a long way by > applying vibration dampeners to a few steel plates. Won’t do much for > the low noise, but it is not as annoying as high pitched noise. > i

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Semi jokingly, I found this "JAC OFF" silicone pad that should be working. It is just like my hand, after all. http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=5545417145 Will look for something more rectangular though. i – Hide quoted text — Show quoted text -> I learned something interesting today. My generator makes low pitched > knocking noises from the cylinders, but also some high pitched noise. > To my great surprise, that high pitched noise was mostly coming from > the "bell" cover of the generator head. As soon as I placed both of my > hands on it firmly, the generator instantly became considerably > quieter. The difference was amazing. > My first question is, how come it makes so much noise. It did not > feel as though some moving part was touching it from inside. > My second question is, can I find some material and applicator > (adhesive or magnetic) to attach an equivalent of a human palm, for > vibration control purposes. I am thinking about the silicone "boob" > material, like from better mousepads, or pads for keyboards, on some > advesive backing. > I could buy such silicone boob from say a computer store and attach it > with electrical tape. i would prefer something more professional, if > it would not cost too much. Just how much can such things set me back > and where to find them? I believe I could go quite a long way by > applying vibration dampeners to a few steel plates. Won’t do much for > the low noise, but it is not as annoying as high pitched noise. > i

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I learned something interesting today. My generator makes low pitched knocking noises from the cylinders, but also some high pitched noise. To my great surprise, that high pitched noise was mostly coming from the "bell" cover of the generator head. As soon as I placed both of my hands on it firmly, the generator instantly became considerably quieter. The difference was amazing. My first question is, how come it makes so much noise. It did not feel as though some moving part was touching it from inside. My second question is, can I find some material and applicator (adhesive or magnetic) to attach an equivalent of a human palm, for vibration control purposes. I am thinking about the silicone "boob" material, like from better mousepads, or pads for keyboards, on some advesive backing. I could buy such silicone boob from say a computer store and attach it with electrical tape. i would prefer something more professional, if it would not cost too much. Just how much can such things set me back and where to find them? I believe I could go quite a long way by applying vibration dampeners to a few steel plates. Won’t do much for the low noise, but it is not as annoying as high pitched noise. i

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