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Author Topic: Genset vibration dampners, What are you using?  (Read 5348 times)
TomC
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« Reply #15 on: September 13, 2006, 07:40:53 AM »

Chris- With the rear gen, have you weighed your bus for axle weights?  I know with my gen mounted in front next to the front seat like a front engine, I'm at 10,500lb in front and 20,500lb in rear.  If I had mounted the gen in back it would have been more like 9,900lb in front and 21,100lb in rear. Getting weight on the front axle is always hard with a bus conversion-that's why I put mine in front.

Brian- It is true that the Powertech enclosed are quieter than open gensets.  But-you might consider still doing some sound insulation around the mounting area.  Then you'll really have a quiet genset.  As far as I'm concerned, there is no such thing as a too quiet generator.  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
belfert
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« Reply #16 on: September 13, 2006, 09:50:16 AM »

Brian- It is true that the Powertech enclosed are quieter than open gensets.  But-you might consider still doing some sound insulation around the mounting area.  Then you'll really have a quiet genset.  As far as I'm concerned, there is no such thing as a too quiet generator.  Good Luck, TomC

I may in the future add some sound insulation on the sides of the bay, but at least the Powertech eliminates having to do remote radiators, blowers, and all that extra stuff to get fresh air to the generator.

I had to do some customization of my former condenser compartment to fit the Powertech, but it should fit real nice.

Brian Elfert
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FloridaCliff
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« Reply #17 on: September 15, 2006, 12:04:49 PM »

I bought vibration dampers for equipment from Grainger.

Find out the weight, size and divide the dampers up to hold the total.

Easy to install and it is amazing to touch the generator frame and below it to feel the difference.

I upped mine by 25% over weight for good measure.

Cliff
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1975 GMC  P8M4905A-1160    North Central Florida

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Chris 85 RTS
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« Reply #18 on: October 03, 2006, 09:28:06 AM »

Chris- With the rear gen, have you weighed your bus for axle weights?  I know with my gen mounted in front next to the front seat like a front engine, I'm at 10,500lb in front and 20,500lb in rear.  If I had mounted the gen in back it would have been more like 9,900lb in front and 21,100lb in rear. Getting weight on the front axle is always hard with a bus conversion-that's why I put mine in front.

Tom, my genset goes in the space previously occuppied by the bus A/C equipment, which has to have weighed more than the genset, not to mention the weight of the A/C compressor I also removed.  Also, as I have a centered bath configuration, my conversion weight on the rear is much lower than the middle/front weight.  So, although I have not weighed in yet, I doubt I'll have a problem.
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1985 GMC RTS II 40x96 6V92TA MUI V731 IFS
Chris 85 RTS
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« Reply #19 on: October 03, 2006, 09:32:52 AM »

I just bought the same genset.  Doesn't the Powertech already have vibration isolators built in so none have to be added?  My reason for buying the Powertech is so I wouldn't have to do soundproofing and vibration isolation.

Brian Elfert

Brian, the PT may have isolators built in, I know the engine does sit on large rubber washers, but I also needed a way to be able to slide the unit in and out for service or repair.  So, I killed two birds with one stone.   I also added sound barrier to the rear bulkhead and built a plenum under the unit to duct the hot gen head and radiator exhaust out of the compartment.  I put duct board in the plenum and it made a huge difference in the sound.  We can now sit right next the rear doors and have a very normal conversation.  In fact, I can not barely hear the exhuast which exits on the roof.
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1985 GMC RTS II 40x96 6V92TA MUI V731 IFS
H3Jim
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« Reply #20 on: October 03, 2006, 10:02:03 AM »

chris,

How did you route the exhaust throughthe roof? 
Did you use double, or triple wall, or flexible hi temp rubber hose made especially for exhaust pipes? 
How did you seal the roof opening - did you use a flange?
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Jim Stewart
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« Reply #21 on: October 03, 2006, 02:07:13 PM »

I guess I should not have said exits through the roof, it would have been more accurate to say exits through the rear cap.  On the RTS, the area above the engine is actually external to the interior of the bus, separated by an all steel firewall.  It is an external compartment.  My exhaust is in this compartment, and just has a 1.5 inch tube running up, with a 90* mitered turn facing rearward. 

I think this pic will help clarify.  The exhaust (not yet installed here) goes straight up just to the right of the genset.

http://new.photos.yahoo.com/cpeters1_32950/photo/294928803157749282/68
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1985 GMC RTS II 40x96 6V92TA MUI V731 IFS
H3Jim
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« Reply #22 on: October 03, 2006, 07:36:02 PM »

Thanks for the pics link, what a great place to put it!  You have done a lot already.  the basic infrastructure and utilities sure can take a long time.
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Jim Stewart
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FloridaCliff
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« Reply #23 on: May 20, 2009, 05:00:25 PM »

I am replacing my Genset, any new ideas on vibration isolators/sources.........

The new genset requires a complete rework of my existing mount/slide, so I am all ears.....

Cliff
« Last Edit: May 20, 2009, 05:05:58 PM by FloridaCliff » Logged

1975 GMC  P8M4905A-1160    North Central Florida

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gmbusguy1
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« Reply #24 on: May 20, 2009, 08:16:50 PM »

Cliff, I mounted my genny to a 1/4 inch steel plate and then isolated that plate with 4 lord rubber mounts from Dick at Wrico they work great

HTH

Chris
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JackConrad
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« Reply #25 on: May 21, 2009, 04:37:40 AM »

I am replacing my Genset, any new ideas on vibration isolators/sources.........
The new genset requires a complete rework of my existing mount/slide, so I am all ears.....
Cliff

Cliff,
   Did you get a generator from Jeff?  Jack
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FloridaCliff
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« Reply #26 on: May 21, 2009, 05:58:14 AM »

Cliff,
   Did you get a generator from Jeff?  Jack

Yes I did, and thanks again for the lead on that.

I ended up getting the PowerTech CD-8, Compact Diesel 3cyl-8Kw.

It seems to have pretty good isolation mounts from the engine and generator to the mounting plate,
but I was thinking of adding another set from the mounting plate to my slide.

I am going to be able to reuse my slide, just need to weld a few new mounts on it. 

Since I have plenty of room in the compartment, the idea of adding an additional isolation point came to mind.

How did you mount yours?

Chris,   Thanks for the info!

Cliff
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1975 GMC  P8M4905A-1160    North Central Florida

"There are basically two types of people. People who accomplish things, and people who claim to have accomplished things. The first group is less crowded."
Mark Twain
Jeremy
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« Reply #27 on: May 21, 2009, 11:08:30 AM »

I got a set of proper mounts for my generator from a friend who's a big cheese in a company that sells NVH solutions to automakers etc (he tells some interesting stories about well known car models which had huge vibration and noise problems before his company worked on them). He asked the weight of the generator and the number of mounts it needed, ran the numbers through his computer and supplied the mounts that were most suitable from their product range. The mounts themselves are of the 'mushroom' type, but I don't really know what their particular characteristics are. If it helps, this is the company where they came from:

http://www.simritna.com/products/vibration_control_devices.asp

Jeremy
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« Reply #28 on: May 21, 2009, 05:15:23 PM »

Engine mounts for Cummins, Caterpillar, even Series 50 (not 60) include a fair amount of vibration dampening. Mount the genset on a really solid plate and use the engine mounts to attach it to a rail system, then bolt it in place (remove the bolt and slide it out for
inspection or service)

You might have to try a few different ones as the gensets also resonate at different frequencies and this isn't transmitted mechanically.
it just is. I've tried lots of them on all sorts of different gensets but no two are exactly the same. Try approcahing a good sized diesel shop - they usually get in wrecks or blown engines with good engine mounts they can no longer use, and believe it or not, some wear is actually a good thing.

Cummins mounts seem to offer the greatest vibration dampening for some reason.
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cody
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« Reply #29 on: May 21, 2009, 05:56:25 PM »

My gut feeling would be that using an engine mount for a bus engine to mount a generator wouldn't be practical, sorta like needing a cruise ship to haul a deck chair.  The mass presented by an engine isn't even close to that of a generator, I would think it would be far too stiff to provide much of a cushion or damping effect.
« Last Edit: May 21, 2009, 06:00:57 PM by cody » Logged
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