Generator Isolation Mount

[Richard and Rhonda]

I am toying with the idea of putting my gennie on air bags to reduce the low freq vibration in the coach. I am curious as to how Newell handled the exhaust routing using that setup. Somehow you have to account for the generator moving up and down with a flex coupling on the exhaust. I would like to know how Newell did that and retained the slide in and out capability. I know how most Prevost conversions do it, but it requires that you disconnect the exhaust to get the gennie to slide out. I really don't want to crawl under the coach to release the generator.

If you know, or you can take pictures of this airbag setup if you have it, would you mind pointing me in the right direction?

[encantotom]

right on,

i have wondered the same thing many times. however, the way my exhaust that has a pipe slide inside a pipe is very sensitive to position and will bind up easily not allowing the genny to come out. i know that because i tried to adjust it to provide the least amount of vibration noise.

the other thing is that the front body panel is very closely aligned. since it is attached to the genny, if the genny bounced up and down much on the mounts, it would hammer the body panel on front.

someone who has airbag genny mounts should be able to tell us easily

tom

[Richard and Rhonda]

A little more info. What sealed the deal was sitting in a Prevost conversion with the gennie running. When if first fired, it felt and sounded just like mine. A low freq rumble coming from the floor. When the air bags filled the sound went away. I could barely tell it was running.

I found the airbags and talked to some gennie experts to learn to have to have two pressure regulators. One for the front and one for the back since the gennie is rear end heavy you run two different pressures to keep it level.

However, none of the gennie experts I talked to had any suggestions about how to isolate the pipe within a pipe system Newell uses for the slide out.

[encantotom]

richard,

what about my other concern? that the outside panel that bolts to the front of the radiator frame? if it moves up and down with an airbag, i dont see how that isnt going to smash that panel all up?

tom

[tuga]

Richard,

My generator is mounted on air bags. If I remember correctly there are 4, one on each corner. When the generator is running you can feel it from the driver's/passenger seat.
It's not excessively noisey, but you can hear it running.

The Prevosts have their generators mounted in the middle of the bus and you are correct they are very quiet. They use a good deal of sound deadening material. Prevosts install the generator radiator in a separate bay from the generator engine. I don't know if that reduces the noise in some way, but it might!

If I remember correctly my 1993 Newell had air bags on the generator. I am surprised that your 1995 doesn't have the air bags. That's odd.

[folivier]

Made me look, my 93 has rubber mounts.

[HoosierDaddy]

My '93 has air bags with an air pressure regulator. The gen exhaust is through the roof about mid way back on the drivers side. The gen exhaust pipe has an "S" shaped section of flex pipe that bends to allow the gen to slide in and out. I've noticed that both of my Newells gens are quieter and smoother after they get warmed up....a characteristic of a diesel engine.
The gen in my '78 (a Kohler/Perkins) had an annoying "knocking " sound. I just thought that was typical for a diesel engine. After investigating I found that one of the bolts that hold the fuel injector in was slightly loose. After tightening it down the noise was reduced.

[HoosierDaddy]

Oh, and yes Tuga you are right. I did some research before I reworked the gen compartment on my '78. By remote mounting the radiator the Prevost converter can more completely seal the engine bay thus minimizing engine sound emissions. Squirrel-cage fans and carefully "ducting" incoming and outgoing air also reduce noise emission.

[encantotom]

dean,

i understand now the flex hose for exhaust, though i am not sure where to actually get it.

that said, i am still curious as to how the front body panel that is bolted to the front of the radiator wouldnt go up and down with the air bags causing it to bind when fully in and flush with the front.

tom

[HoosierDaddy]

Hi Tom,
There are two frames. The engine/radiator is mounted to a frame.
That assembly is mounted to the sliding frame via 4 air bags. The front cover/body panel is solid mounted to the sliding frame seperately just in front of the radiator. The cover/body panel only slides in/out with the sliding frame.

[Richard and Rhonda]

Tom,

My thinking was the radiator remained hard bolted to the slide carriage, the motor and generator floated on the air bags, the rubber coolant hoses should allow for an inch of flex or so.

I am very interested about the location of the flex. Is it between the generator exhaust and the pipe that slides into the exhaust system. Or is it part of the stationary exhaust system.

Seems to me in order to isolate the vibration, then both the generator vibrations have to be isolated from the coach. The air bags are obvious, but the exhaust system must be isolated as early as possible.

Tuga or Dean, if you could take a pic when it is convenient, I would appreciate it.

Thanks,

[tuga]

Richard,

I will take some pictures tomorrow. It is supposed to rain, so it the pictures may not be too good. But I will do my best.

[Richard and Rhonda]

Thanks Tuga, don't put yourself in the wet. It was yucky here today. I am in no hurry. Just one of those things that you get to thinking about when the weather is too cold to go out and play.

[HoosierDaddy]

I need to correct my earlier post. I was thinking of the mount setup on my '78 Newell.
Richard is right. My engine is mounted on the air bags and the radiator is rigid mounted. This pic is of my '93.

[Richard and Rhonda]

HoosierDaddy,

Can you get a pic of the exhaust flex coupling?

Thanks

R

[encantotom]

i talked to dean last nite and he said that he was remembering a previous coach. his exhaust still slides inside each other like mine does.

it sounds like the putting of airbags in if can get the part numbers shouldnt be hard at all.

the bigger thing is realigning the exhaust.

mine has a slight rattle where the two pipes slide inside each other. i made a aluminum plate to hold the fixed pipe up so it wouldnt rattle, then it bound enough to not allow the slide to open.

those little airbags cant be very expensive can they?

tom

tom

[Richard and Rhonda]

I'm always "courtin disaster" to steal a phrase from Lynyrd Skynyrd, so I keep trying to make the idea work.

The airbags are about 50 to 60 each as I have done a rough source on the internet.

The trick is to alter the motor mounts to get the generator to ride in roughly the same position as it does with the solid mounts. kohler made a kit with bags and mounts back way back when, I am trying to get price and availability on the kit.

The second trick is to isolate the exhaust. My initial thinking is that the flex piece needs to go as early as possible after the turbo and before the long piece that slides into the stationary exhaust system. An alternative is to isolate the system AFTER the two sliding pieces.

The challenge with the Newell setup is the design feature that they have where the two exhaust pipes mate with one another. The keep continuity of the exhaust system with the generator extended which then dictates two long runs of straight pipe, the moving pipe sliding inside the stationary pipe. This does present a challenge harder than the Prevost style setup, where the exhaust is connected through a piece of flex which is simply disconnnected when you want to service the generator.

Nothing like a challenge, right?

[tuga]

Richard,

I took a few pictures of my air bag generator set up. Hope I can post them. Here goes!

[Richard and Rhonda]

Well Tuga,

I hate to burst your air bag, but you saved me the trouble of posting pics I just took, because they look exactly like yours. Sorry to be the bearer of the news, but those aren't air bags, you have solid isolation mounts just like I do.

I measured mine and they are about 3.75 inches tall, so I should be able to use the 3 inch airbags with a spacer and retain the same height. All I have to do is figure out the exhaust isolation setup.

[tuga]

Sorry Richard, I thought those were air bags!

[Richard and Rhonda]

No worries mate. The good news is, if I get the air bag thing figured out and it works, then there is a method for quieting down your gennie. :-)