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Author Topic: Genset vibration dampners, What are you using?  (Read 5675 times)
JackConrad
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« Reply #30 on: May 22, 2009, 05:06:30 AM »

    Looking in the Grainger catalog, it looks like most of the noise/vibration isolation mounts are sized for  a specific weight. Fist step would be to determine weight of the genset. 
   Years ago, we purchased a set of Onan mounts to replace those missing on a used genset we purchased. When I ordered the replacement set, I was told to be sure I put the correct part number on each end (generator end and engine end) because of the different weights of each end of the genset.  Jack
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« Reply #31 on: May 22, 2009, 05:15:34 AM »

That would be my thinking Jack, the weight would be a critical factor in determining damping of the unit, correct me if i'm wrong but vibration is movement of the unit lol, that movement would be transfered to the bus if not for a damping effort achieved by a cushion of some sort (do I sound like an engineer yet? lol).  If the cushion is too heavy or stiff that would remove the flexibility of the mount and that flexability is critical to isolating the movement from the stationary part of the mounting system and eliminating the vibration and inherant noise from that movement.  (now my head hurts)  I'm sure we could model a set of co-efficients that would show the different movements under different weights and vibration levels, ( now I've gone too far, I hate myself and forgot what I was saying)
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kyle4501
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« Reply #32 on: May 22, 2009, 05:44:39 AM »

The reason Grainger lists weight only is probably due to limited catalog space. Besides, identifying the weight is easy & something anyone can do.  Wink


A quick web search yeilded some interesting reading on the subject ;

http://www.fabreeka.com/tech/Primer_Vibr_Isol.pdf


Seems frequency is very important, but how many people have the capacity to measure (much less understand) that?


I like the pneumatic tire approach, it seems to solve several problems for me at once.  Cool
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JackConrad
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« Reply #33 on: May 22, 2009, 06:17:06 AM »

Kyle,
   Thanks for the link.  I think our problem is more harmonics and resonance. Outside our coach, the genset id fairly quite, but inside, it is almost more like we "feel" the genset.  Our PowerTech has factory installed isolaters between the genset and the steel pan they attached it to. When we installed it, I threw a piece of 1/2" closed cell foam between the genset and the compartment floor.  My thinking at the time was that it I installed additional mounts between the steel pan and the compartment floor, the steel pan might vibrate and cause more noise/vibration. After reading this article, it looks like it is time to re-evavluate my genset mounting system.  Jack
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« Reply #34 on: May 22, 2009, 07:36:17 AM »

I mentioned before that my friend has told me of the work they do to cure vibration problems on behalf of the car manufacturers. Apparently one of the things they do is to deliberately design-in an 'out of phase' vibration (like anti-sound) to cancel out the vibration coming from the engine or gearbox or whatever. He told me that on one Volkswagen model he was working on had a particularly severe problem, and they ended up designing special flexible steelwork under the battery, such so that the weight of the battery was used to generate the large amount of 'out-of-phase' vibration they needed.

I imagine that a stationary generator mostly running at a constant speed would be an easy nut to crack by comparision

Jeremy
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« Reply #35 on: May 22, 2009, 09:11:55 AM »

I know my Powertech has really good soft engine mounts-maybe talk to them directly in Leesburg, Flor.  Also using air bags are the best.  Good Luck, TomC
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« Reply #36 on: May 22, 2009, 02:09:34 PM »

My plan is to just make an isolation box, and plop it on a mat from a horse trailer.  I'm guessing if that 1/2" of vinyl type material should nix most of the vibration. =)

If that don't work, guess I'll have to actually give it some thought.  LoL

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« Reply #37 on: May 22, 2009, 03:34:28 PM »

I am getting ready to install my diesel genset. The unit weighs about 660 lbs. I want to dampen the vibration if possible. I also am going to build a box to quite the unit and install high efficiency fans to help with cooling. The unit is on a joey bed for easy access and maintenance.

Any thoughts would be appreciated.  Cool

3 cylinder Deutz diesel with a 47 kw generator. I know, that is alot of electricity. I got the complete unit at a price I couldn't pass up and the owner had no idea the kw output. Valley Power did a total check and replaced the resistor board and we are off to the races. I have an additional panel on the unit for external connections of 120 and 240 volts. I am thinking of selling power when the first big earthquake or flood hits Shocked


Have a great day! Grin

Grant





Grant
If I were you I'd hook that bad boy to your house for when the rolling black-outs start again. We generated our own power for years.
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