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Old 11-01-2006, 04:10 PM   #1
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Genset on extended tongue safe?

Not really sure where to fit this question; it's kind of frame related so I'll stick it in the frame and axle section. If it belongs elsewhere, I'm sure one of the moderators will help out by moving it

OK, so I'm going to build a brand new, from scratch, improved design frame for my Airstream. The question is: Is it safe to put a generator up front on the tongue, near the LP bottles? I could put a barrier up there to keep leaking LP from getting around the exhaust pipe of the generator. As long as its well ventilated, is there any danger in putting a permanently mounted genset up front?

Would it be better in the back? If so, why?

My plan is to set this thing up balance wise and strength wise so I can haul my 350lb Kawasaki on the a specially made mount on the back bumper. I know this would destruct a normal Airstream frame, but the one I'm designing will do this easily. I know it can lighten the tongue load a lot, but the genset up front should help to balance it out. As well, I could mount a spare up there. The arm is longer from the axles' centerline to the tongue than to the back bumper, so it's an easy calc to figure out how much it takes to balance it all out.

So the biggest fly in the ointment I see is: is it safe to have a genset up by the LP bottles? What do you all think?

Thanks!
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Old 11-01-2006, 04:28 PM   #2
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Safety question

You would most likely have no problem.....BUT if you have a leak that reaches an ignition source (most likely at the generator exhaust or internal electrical arc at the brushes) you will have a fire. Being in an open area and not confined it will probably not go boom. Still, you don't need a fire.

Can you reverse your plan? Put the generator on the rear and the bike on the front? That would seperate your fuel from an ignition source at the generator.

My 2 cents.

Dave
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Old 11-01-2006, 04:34 PM   #3
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Quote:
Originally Posted by JimGolden
...Is it safe to put a generator up front on the tongue, near the LP bottles? I could put a barrier up there to keep leaking LP from getting around the exhaust pipe of the generator. As long as its well ventilated, is there any danger in putting a permanently mounted genset up front?

Would it be better in the back? If so, why?
Jim,

IMO, first stage design goal would be to keep the generator's general heat & not necessarily source of ignition away from the propane cylinders. Liquid fuel at ambient pressure (gasoline) is one thing, but if an LPG cylinder overpressurizes, the relief valve might say "hello" with gusto.

If you make provisions for the heat, and it could be in the form of a removable shield installed only for generator use, with proper design you can cover the possibility of leaking LPG.

IMO, anything mounted on the bumper would look bad aesthetically.

List of assumptions include your extended tongue design taking into account backing up at tight turning radii?

Tom
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Old 11-01-2006, 04:39 PM   #4
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No doubt your new frame will handle the weight overall but where the weight is located may introduce handling issues.

Trailer builders soon realized that getting as much of the overall weight on or close to the axles produced a trailer that had very good handling characteristics. On the other hand when they loaded up the front or rear ( or both ) with excessive weight handling went out the window. Something to keep in mind with your project.
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Old 11-01-2006, 05:40 PM   #5
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hello Jim ,there was a thread here about gensets on the rear . Don't do it.. if you get rear ended there can be a fire hazzard for you and the vechicle that hit you..some one can and will get hurt..
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Old 11-01-2006, 06:48 PM   #6
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This is a no brainer for an LP conversion to the generator. That would have fewer flammability issues compared to gasoline. I'd probably look at a Yamaha large enough to power the A/C while you're at it. The outer case on these is plastic -- they're insulated enough to be cool to the touch except at the exhaust. You'd probably want to have a decision and one of these in hand before firming up your design. Remember to coordinate A-frame design with your WD gear too.
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Old 11-04-2006, 01:44 PM   #7
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Quote:
Originally Posted by JimGolden
My plan is to set this thing up balance wise and strength wise so I can haul my 350lb Kawasaki on the a specially made mount on the back bumper. I know this would destruct a normal Airstream frame, but the one I'm designing will do this easily. I know it can lighten the tongue load a lot, but the genset up front should help to balance it out. As well, I could mount a spare up there. The arm is longer from the axles' centerline to the tongue than to the back bumper, so it's an easy calc to figure out how much it takes to balance it all out.

So the biggest fly in the ointment I see is: is it safe to have a genset up by the LP bottles? What do you all think?

Thanks!
Every installation that I have seen in our shop where a generator has been installed on the A-frame, has led to absolute failure.

The more weight on the A-frame, the more it will flex and the more it will fatigue crack, when towing.

Add to that the possibility of unbalanced running gear and/or over hitching and your guaranteed a failure.

You can however, replace the entire A-frame with heavier duty steel and maybe, just maybe, not have a problem.

The last one in our shop, came in with "NO" A-frame, as it completely broke off.

Andy
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Old 11-04-2006, 04:36 PM   #8
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Exclamation We interrupt for this special diversion

Quote:
Originally Posted by Inland RV Center, In
...The more weight on the A-frame, the more it will flex and the more it will fatigue crack, when towing.

Add to that the possibility of unbalanced running gear and/or over hitching and your guaranteed a failure....
Jim,

You have probably got Andy's first point covered, but I would like to sidetrack (not hijack ) your thread to share something I found while setting up my drawbar to accomodate the height gained due to my Overlander's new axles: My A-frame appears to be bent upward.

While my Airstream's previous owner did not carry an additional load on the tongue, he did use 1000 pound spring bars in conjunction with a 3/4 ton tow vehicle for a period of seven years of active camping. After reading Andy's previous posts on the topic, I have concluded that my Airstream was over-hitched during that time. I believe the too-stout spring bars bent the A-frame.

While I was blissfully ignorant, during the refurbishment, of Andy's insight, much time was taken to examine the frame members, and I observed no cracks. So I think I am okay.

But since I observed remarkably better towing characteristics after moving to 550 pound spring bars, I wanted to reinforce Andy's statement.

We now return to the thread's regular programming...

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Old 11-04-2006, 04:57 PM   #9
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Quote:
Originally Posted by TomW
While my Airstream's previous owner did not carry an additional load on the tongue, he did use 1000 pound spring bars in conjunction with a 3/4 ton tow vehicle for a period of seven years of active camping. After reading Andy's previous posts on the topic, I have concluded that my Airstream was over-hitched during that time. I believe the too-stout spring bars bent the A-frame.

Tom
Over hitching, in time, will permanently bend the A-frame upward.

Is it stressing itself and the welds?

You betcha.

Andy
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Old 11-06-2006, 12:04 PM   #10
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Thank you all for your replies. You guys certainly bring up some good points.

As to hauling the bike on the back, yes I am concerned about the handling of it. I don't know any other way to check for that other than to build it and try it. I've hauled heavy concentrated loads at the end of my utility trailer and it did OK, but it doesn't have as much overhang as the Airstream does. If it does indeed handle poorly due to having too much weight at the extreme ends, then I"ll just not do it anymore, and go to hauling a 30lb bicycle instead of a 350lb motorcycle. My belly would probably thank me for that I know my new frame will take the weight, but the handling is an unknown. All else being equal, it'd be nice to concentrate all the weight over the wheels.

I'd read about the over hitching on other threads previously. It took me awhile to understand it. If I get this right, basically, the heavier your tow vehicle, then the less you need to "spring" the hitch height up with bars. Further, for the bars to be effective, you need to bend them a certain amount. I used to know what that amount was, but I don't recall. I think like 1/2" maybe? You have to do this to get the benefits of the bars for sway control, etc., other than just raising the thing back up (which you could do with diamond bars that don't flex at all, but then they wouldn't do much for you to control sway, etc.) So if I understand this right, then for the bars to provide handling benefits in addition to weight distribution, if the truck is sprung heavily, then you need to use lighter bars, because you're not really trying to raise the height a whole lot. So the light bars allow you to get the proper amount of flex in them to give you the handling benefits, while also raising it the minimum anount you need. With a smaller tow vehicle, you then have to use heavier bars so that you don't bend them too much while raising the hitch back up to where it should be.

Am I getting this right? It's kind of complicated...to me anyway

I've got a Reese Dual Cam that came with the trailer. I've no idea what rating the bars are. They're so old that all the stickers and writing are long worn away.

When I towed the trailer home, I just set it on the ball and went. I've got a 3/4 ton HD Dodge with the 4-doors and long bed (it's long as a freight car...) and it pulled it home just fine. When I actually start traveling, I don't plan to pull it this way. I'll set up a proper hitch rig. It did seem to me that I'd researched all this way back and I was going to try and get a set of the 550lb bars. I think Andy may have gone all over this in some previous threads that I read last year. I know its been covered well on here.

Didn't Airstream put generator on some of their travel trailers? If so, where did the factory put them?

Thanks!
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Old 11-06-2006, 12:36 PM   #11
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Quote:
Originally Posted by JimGolden
As to hauling the bike on the back, yes I am concerned about the handling of it. I don't know any other way to check for that other than to build it and try it.!
Jim.

The bike does not weight 30 pounds when you carry it on the rear bumper.

You must consider the "moment arm." That is how far from the rear axle will that bike be?

It's about 12 feet. Therefore you must multiply the weight by the 12 feet. Now your bike weighs 360 punds, sitting still. Then when traveling you hit some bumps, that weight instantly multiplies up to several times that moment arm weight. Another way to say it, is that weight can multiply to over 1000 pounds, very easily, when hitting bumps.

Questions then come up regarding will that sudden weight change have any effect on the stability of the towing? Also, will it have any effect on possible rear end separation?

The rating of Reese bars are simple to measure. Measure the top of the bar as it enters the trunnion. That measurement will be 1" (550#), 1 1/8" (750#) or 1 1/4" (1000#). Those ratings only apply when the bars are coupled with the dual cam sway control.

The basic hitching rule also depends on the tow vehicle. For standard cars of long ago, without assists, for your trailer, you would use 1000 pound bars. With a 1/2 ton truck, without overload springs or other assists, you would use a 750 # bar.

A tow vehicle that is greater than a 1/2 ton truck, would then use a 550 pound bar. A Suburban with an overload spring, as an example would require a 550 pound rating. This is the category that your TV is in.

A ideal bend in Reese bars using the "cam" type sway control is 1 inch, or more. During my traveling days that bend was 2 inches. Could tow all day with two fingers. How nice that was.

Airstream in some 1973 models, installed a very small 12 volt generator, solely to charge the battery. It was very light weight, about 60 pounds as I remember, and ran on Propane.

However, the carb had to be adjusted when you changed altitude by as little as 2000 feet. It shortly became a pain in the neck. However, when it did work, it did a great job. You started it from the front rooflocker, and it also had a timer, so that it would shut itself off after a period of time.

Andy
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Old 11-06-2006, 01:48 PM   #12
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Jim, Can you just put the motorcycle and a portable generator in the pickup bed? Sounds a lot easier and safer to me!
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Old 11-07-2006, 08:42 AM   #13
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Dan,

It's starting to sound like that may be the way to go. Although, if I do that, then I'd have to remove my cap and lose all that storage space. I was really hoping to carry the "little' Kawi out back.

Andy,

Your explanation on the bars was great. Thanks. I will go and measure mine. I understand about the moment arm idea. The frame I've designed would handle the weight no problem at all, as far as flexing and bouncing go. But the handling is another issue altogether. I have to think on this some, but much as I hate to admit it, you guys might be right on this one.

I did see a huge fifth wheel going up the road recently with a Harley on the back bumper. The big twin easily weighs double what my little enduro weighs, but the 5'er probably weighs 2.5 times what my "little" Airstream weighs. And, nothing says that 5'er handled well either.

As to the generator, I'll figure something out. I want to build a camper that's its own self contained little world. I'm planning a gutting and total rebuild, so I could maybe locate a generator amidships somewhere. It's just that noise then becomes a factor. And, I'd have to be very wary of fumes. At least, moreso than if it was out front.

I'm going to make the tongue from the same steel I do the main frame, so it will be much beefier than OEM. So, I'm not worried that the generator would bend it up there.

But, I do have a question: Why don't the 1000 lb dual cam bars bend the tongue when used behind a passenger car, if they do when used behind a truck? I would think that if you bend the bars 2", no matter what you're hitched to, you'd be putting a tremendous force into the tongue?
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Old 11-07-2006, 10:55 AM   #14
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Quote:
Originally Posted by JimGolden

But, I do have a question: Why don't the 1000 lb dual cam bars bend the tongue when used behind a passenger car, if they do when used behind a truck? I would think that if you bend the bars 2", no matter what you're hitched to, you'd be putting a tremendous force into the tongue?
The suspension system on trucks is much heavier than cars.

It's hitting bumps that causes the problem.

Therefore when hitting bumps, more energy is transfered to the A-frame from a truck than a car, through the load eqaulizing hitch.

When you stiffen the bars, you reduce the flexing from a given bump. Add to that the rigidity of typical truck suspension systems, and you now have created a cause for the bent A-frame problem.

Reducing the rating of the bars when using a heavy duty tow vehicle, also reduces the stresses placed on an A-frame, again with a given bump.

I also bent the A-frame on a 73 31 foot Airstream. I used a 1973 Buick Electra as a tow vehicle. The bars were Reese 1000 pounds with the dual cam. I had approximately 1200 pounds of tongue weight, plus a huge trunk load. I also had the car equipped with an additional fuel tank so that I could carry 65 gallons of fuel. Add to that tools etc, and there went the weight.

I also had air shocks and air bags. Each system had it's own pressure gauge, plus I could add or subtract air pressure as I was moving. So cars can cause the same problem, depending on the setup.

That set up was used to do many experiments while traveling, so that we could set forth some guidelines as to what is ok and what is not ok. I was the sole field special representative for the old insurance division of Airstream, called Caravanner Insurance Company. We established many do's and don'ts, along with documentation, so that any given situation could be duplicated.

That data also allowed us to predict "loss of control accidents waiting to happen," and they did, BIG TIME.

We wanted to have all the rigging information added to the insurance policy questions, so that we could insure someone or not, based on that research data. But the Airstream powers that be at that time, nixed the idea, but accepted the facts. Prior to that study, Airstream said over and over again, that it was impossible to figure out how or why a loss of control accidents happened. WRONG.

After I completed that research, Airstream then accepted the facts and causes of loss of control accidents.

That was back in 1970 and 1971. The causes of loss of control accidents, specifically towing an Airstream or Argosy trailer, remain exactly the same today.

The guidelines and causes of loss of control accidents is easily published.

The difficult part, is to get people to accept those facts.

Sometimes, as in your case, you found out the difference. It's people like you, that can steer the cultivation in the right direction, far better than I.

I am all to many times looked at as a dealer, with a sole purpose of making money.

That is not true.

I also, to a very large degree, promote "SAFETY", which only has a price tag to the owner of the rig, and his family, not to me or Inland RV Center, Inc.

Many years ago, there was a device called Safe T Tow. We are working on bring that to the market place, within a year if possible.

It's a device that mounts in the rear end of your tow vehicle. It automatically applies the trailer brakes, faster than you can, in the event of a possible loss of control situation. It also warns you of instability, such as a possible high cross winds or even a low tire. With it, it becomes almost impossible to have a loss of control accident.

I demonstrated that device, many years ago, at a number of different Airstream rallies. It's acceptance was outstanding.

It carried some 19 patents. We have modified it, and have applied for additional patent protections.

Stay tuned.

Andy
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