cabover camper overhang question

[Jfet]

How far would you be willing to go past the top of the windshield on a Isuzu or Mitsubishi cabover truck for a camper overhang?

It is 54 inches from the back of the headache rack on our Isuzu NRR flatbed to the top of the windshield where it starts to curve. I would like to go 72 inches on the length of the camper overhang (most slide in truck campers are more like 85 to 90 inches!).

Also, what gap would you leave between the top of the truck cab and the bottom of the camper overhang? I am leaning toward 4 inches. Thanks.

 

[dlh62c]

What is its intended use, sleeping and/or storage?

If the cab tilts forward, a cab-over-camper overhang could make servicing the engine problematic.

If your going to use it for sleeping, you have to design in some air flow, then add additional insulation around it. Its one of the few places in the camper that you'll often come in contact with the body sides. Depending on how high the ceiling is from your head, a night of light rain, may roar like hail on a tin roof.

How much free space above the bed do you plan to have? At least one meter would be nice.

I sent you a PM.

daryl

 

[Jfet]

We are now looking at a Lance 1191 so the camper overhang would be for sleeping. It is around 36 inches above the matress to the ceiling (I don't have this exact yet). It does have air flow and venting plus emergency escape.

We will have to make sure it is moderately easy to raise the camper to allow the cab to tilt. I have a drawing on the Isuzu that shows the cab swweeps an arc that is 16.5" above it's normal height. If we have the camper overhang already 4 inches above the cab when it is resting on the flatbed, then we need to jack it up another 13 inches to allow the cab to swing clear (or we need to drive the truck foward enough to have the cab free of the overhang. Member jhrodd has a very similar setup (large camper overhang) and seems to do ok. He did start with a new vehicle though, so maybe has fewer engine problems, heh heh.

 

[jhrodd]

I don't think you're going to want to jack the camper up another 13 inches. My Atwood jacks don't reach the ground at full extension, I put 8" blocks under them and even at that height the thing is pretty wobbly. I wouldn't jack it up in a strong wind. To drive out from under you would also have to remove whatever is on the bed behind the camper. Plus you have the problem of the 8' wide flat bed, mine is 88" wide and leaves me 4" on each side to drive between the jacks. You would need swing outs front and back, at full extension, that might be scary.

 

[Jfet]

Hmmm, I will have to ponder this a bit. What I could do, since we have to build a platform to hold the bottom of the camper which would normally rest in the bed of the truck, is make a scissor jack type of plate which would lift up the entire camper 13 or so inches when actuated. This would not actually be connected to the camper, but it would be more like if you had a giant flat plate jack in your truck bed and it could raise and lower the camper by pushing up on the bottom. Is that making sense? I don't think it would be very hard to build...

Or I could improve the Atwood jacks, or ???

 

[Jfet]

I don't have access to Rhino on this machine so had to use paint (groan) but here is a simple drawing of the raising mechanism idea:

 

[Jfet]

Or these:

http://www.amazon.com/Camco-57421-Olympian-Scissor-Jack/dp/B000760FXE

 

[SkiFreak]

That's a whole lot of engineering for just being able to tilt the cab.
Have you considered a setup like a dump body? A hydraulic lift could be used to raise the front section of the camper, allowing the cab to tilt and it would also give access to anything located between the chassis rails.



There is another example of the same sort of thing on this page:
http://www.expeditionportal.com/forum/threads/9299-Mitsu-Fuso-Camper-examples/page21

 

[Jfet]

I like the dump body flatbeds, but they are heavier and would be quite complex to add to our existing 20 foot steel flatbed.

Perhaps those off the shelf manual scissor jacks I linked could be attached at the points where you would normall have the attwood jacks, and hooked into the steel fram of the flatbed instead of pushing off the ground. That would cost about $120 for all 4 jacks and allow you to easily and securely lift the camper 13 or more inches off the flatbed. I could store the attwood jacks in a compartment somewhere in case I needed to totally remove the camper from the flatbed.

 

[SkiFreak]

I am guessing that manually winding up that kind of small scissor jack would become old very fast.
Do you have hydraulics on the truck? If so an easier solution would be to do a similar thing with hydraulic rams. If not hydraulics, you could go pneumatics, if you have on-board air.

 

[SkiFreak]

I should also add that those small scissor style screw jacks are only designed for very intermittent use.
I cannot remember how many of this style jack I have thrown away over the years, as the screw wears very quickly, especially if under a reasonable amount of load.

 

[Jfet]

I do have a bunch of 36 inch travel linear slides with brushless servo motors and ballscrews. Accurate to 0.0002 inches and can move 500 pounds at 1000 inches per minute. Thinking those might be a bit overkill though...

Probably we are making this sound like much more of a problem that it really is. Assuming you need to lift the hood once per month, those scissor jacks I linked would likely last at least a year...maybe more if you stored them in a dry place. Rated for 7500 pounds and each one would be lifting less than 1500 pounds. My wife could spin two on one side and I could spin 2 on the other side.

But maybe we will come up with some other clever idea.

How about two truck tire inner tubes, normally deflated, that rest under the camper. When you want to raise the camper, just inflate the tubes.

 

[whatcharterboat]

Hi Jfet,

Many years ago I saw a tray back ute ( not sure what that would be called there) that was converted into a tipper with an exhaust bag jack providing the lift. Simple enough and probably not too hard to manage. I would only raise it just enough to clear the cab too.

If it helps your research into designing the "cab over camper overhang" the term we use in the coach building industry is a "Luton Peak" ....might help with google. https://www.google.com.au/search?q=...yUmQXgsYHQBQ&ved=0CAkQ_AUoAQ&biw=1024&bih=672

If you look at the very first picture there in google images, you will see a Hino with a massive Luton Peak ....but look closely at the pic and you will notice that the section directly above the cab roof( probably a bed base) is removeable so as to allow the cab to raise. I would be investigating this option before making the body tilt.

Good luck mate.

Regards John

 

[SkiFreak]

I would be investigating this option before making the body tilt.

That is a very clever idea.
Weather proofing would not be too much of a challenge with this design either. The only stipulation would be that the camper body were wide enough. The top of the cab on these type of trucks is normally tapered in, which would definitely help.
Excellent link John!

 

[SkiFreak]

Not too sure how robust this design would be on a 4x4 camper... but it is very impressive, none the less.