pivoting frames and mounting campers

westyss

Explorer
Before leaving for a multi-month drive around Europe and Asia, Gary and Monika Wescott did some preventive maintenance on their iconic Turtle 5 camper. It turns out that their torque-free camper mount was designed and built 10 years ago by Midwest Four Wheel Drive, the company that builds the Bigfoot monster trucks. Gary and Monika paid them a visit to inspect and lubricate the camper mount.

The mount attaches the camper to the F550 frame in three places: two behind the truck cab, and a third on a crossmember behind the differential. The rear mount is pivoting, allowing the rear axle to tilt without a affecting the camper. Read a little bit about this feature and see a photo of the pivot pin in Gary's blog post.
http://turtleexpedition.com/across-the-usa-2013-3/

Putting the pivot at the rear of the truck chassis is unusual. Most three point designs put the pivoting mount at the front of the camper, and mount the camper to the frame in two locations close to the axle.
I am not sure where I saw it on their blog but they did have a frame failure of some sort not too long ago, just wondering if anyone knows the reason and the result of it all, was it mount issue or some other issue??
 

haven

Expedition Leader
I think most pivoting designs follow the Unimog model, which puts a pivot point at the front, two stationary mounts at the rear axle, and a pivot behind the axle if the frame and box extend much beyond the axle.

That's fine if you have a Unimog, maybe not so fine for other trucks. A couple of well documented Fuso fg140 frame failures seem to recommend a camper subframe that distributes the weight along the full length of the truck frame, rather than at a few mounting points.
 

Goingbush

New member
Thanks everyone,
I joined the forum to read this thread. Lots of good ideas.

I recently bought a new Iveco Daily 4x4 and am about to start building a subframe (tray) to mount a box module on the back.

I'm going the 3 point mount, using a pair of Landrover Trailing arm bushes NTC9027 to mount the front of the subframe to the chassis and a Toyota SV21 engine mount as the single flexy mount on the rear. Well thats the plan.

building the 1950 x 2000 x 1500 box from coolroom sandwich panels. (like a uhaul trailer) hope to be all done in the next week or 2

now I must check out the rest of the forum.
cheers Don
 

LukeH

Adventurer
If you insist on having pivots I think that having the longitudinal axis pivot at the rear makes more sense. Put it at the front and you force the frame to rotate the camper box when ever it twists. Put it at the rear and now the frame is free to twist under the camper box..
Why would you want that? That means the heaviest bit of the rig has no direct link to the sway bar (or leaf spring stiffness) of the rear axle. This way you have no control over what the body does. In a corner or on an off-camber traverse it's pulling somewhere in the middle of the chassis with only the weight of the engine stopping a front Wheel lifting, and when the front Wheel lifts it's not the torsional rigidity of the chassis running from the lateral mounts of the box all the way back to the rear axle that will stop the rig from Rolling. The whole reason Unicat, Unimog and a whole load of others have the lateral stability as close as possible to the rear axle is so the axle can contribute to keeping the load (box) stable without relying on the very limited rigidity of the chassis. So when a rear Wheel dips into a hole yes the box moves, it looks strange when you see it moving relative to the cab, but that's secondary. As a side note, the weight distribution is calculated so the load is centered over this pair of lateral mounts, so that tis same load is transmitted as directly as possible to the suspension, reducing the danger of chassis failure at some other point load.
Remember that on an evenly loaded flatbed heavy goods vehicle there is a huge point load: the axle pushing upwards.

More important than the fore/aft location of the longitudinal axis pivot is the vertical location of this pivot. If it is either above or below the axis that the chassis twists about it will cause some lateral displacement of the camper box. If the other two supports do not have that degree of freedom built into their design some parts will be flexing and distorting if not built heavily enough, and if built heavily enough will be 'working' their attachment to the chassis. None of this is good for longevity.
Almost right. A three point mount with a point too high or low would mean the twisted chassis tries to shorten one of the sides of the triangle. So in theory you are absolutely right. In reality you have overlooked the fact that the chassis has twisted, therefore it is flexible. As a result it's not the triangle that is forced, but the untriangulated chassis that deforms to accomodate the indeformable triangle.
It's something it can do, and does it without problems as the deformation is tiny compared to the huge twist of the rails.
 

biotect

Designer
DESIGN QUERY re PIVOTING FRAMES

Great thread – incredibly informative!


Perhaps the link has already been posted, but one possible interesting design variant was dubbed by its inventor the “two line pivot floating subframe” – see http://www.kookynet.net/220-cristo-3-ch04-subframe.html .


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The following is a very long post, but I have some rather pressing design questions, questions that I was hoping those with some engineering knowledge and/or practical experience of frame/subframe systems, might be able to answer....:)


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1) The MAN SX 45

A number of times in this thread, a question has arisen:

“Why not just build a chassis frame that is super-rigid, and 100 % torsion free, allowing just a suspension system with extremely long travel to handle the terrain?”

It does seem as if such a solution exists, in the form a very large military truck designed for extreme off-road use: the MAN SX 45, “extreme-mobility”, 8 x 8, all-wheel-drive military truck. See http://freundeskreis-videoclips.de/wordpress/wp-content/uploads/2009/01/the_mobility_elite.pdf , http://en.wikipedia.org/wiki/MAN_SX , http://www.military-today.com/trucks/man_sx45.htm , and http://snafu-solomon.blogspot.it/2013/12/rheinmetall-man-military-trucks-keep.html .

The first link is to a PDF that was once available on the “MAN Military Trucks” website. But it seems that MAN’s military division went through a reshuffle, and is now owned / handled / operated by “Rheinmetall Defence” – see http://www.rheinmetall-defence.com/en/rheinmetall_defence/systems_and_products/vehicle_systems/military_trucks/index.php , http://www.rheinmetall.com/en/rheinmetall_ag/press/news/aktuell_1/news_details_2688.php , and http://www.rheinmetall.de/media/editor_media/rheinmetallag/group/publications_1/companymagazine/newsline/2010_2/Newsline_01_2010.pdf . Unfortunately, Rheinmetall Defence website is much less forthcoming with information, in contrast to the older, now-defunct MAN military division website. So the link just given for the PDF is to a third-party website; hope the link stays active for a while!

Now browsing through this PDF -- again, at http://freundeskreis-videoclips.de/wordpress/wp-content/uploads/2009/01/the_mobility_elite.pdf -- one sees that it describes the MAN SX 45 specifically as having an “extremely torsion resistant box frame” , one that provides “100 % torsional stiffness”. Instead, the MAN SX 45 absorbs all terrain irregularities through its progressive coil spring suspension. And the promised result is that “the body remains unaffected even during fast off-road driving!!”

Does this strike the contributors in this thread as plausible? Wouldn't such a truck still need some kind of pivoting sub-frame for mounting a body?

Or is it indeed possible to eliminate all torsional twisting with a chassis box frame, in a vehicle this large, about 10 m long….?


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2) Brief Note

The SX 45 is basically a “souped up” version of the MAN TGA construction truck, a line of MAN trucks now supplanted by the TGS series -- see http://www.truck.man.eu/global/en/index.html , http://www.truck.man.eu/global/en/building-site-and-heavy-duty-transport/tgs/overview/Overview.html , http://www.truck.man.eu/man/media/en/content_medien/doc/business_website_truck_master_1/TGS.pdf , http://www.truck.man.eu/man/media/content_medien/doc/business_website_truck_master_1/Spezialfahrzeuge.pdf , http://www.man-bodybuilder.co.uk/drawings/euro5/ , and http://www.man-bodybuilder.co.uk/drawings/euro5/chassis/81.99126.0055.04.pdf .

In both the TGS and the SX 45 the two front axles are steerable, but the TGS is 8 x 4 instead of 8 x 8. And of course everything about the SX 45 has been “militarized”, including the ability to withstand outside temperatures from minus 32 to plus 49 degrees Celsius!


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3) “Fully Integrated” Expedition Mobile Home?

My second question is more of a design query. Some of the largest expedition vehicles made by ActionMobil or Armadillo (a Chinese company), are based either on a Mercedes Benz Zetros chassis, or a MAN TGA chassis, or more recently on a MAN TGS chassis. For examples of ActionMobil vehicles, see http://www.actionmobil.at , http://www.actionmobil.at/page12/page12.html , and http://www.actionmobil.at/page16/page16.html . And for Armadillo vehicles, see http://www.armadillo-rv.com , http://www.armadillo-rv.com/Product.aspx , http://www.armadillo-rv.com/ProductDetail.aspx?ProductID=7 , http://www.armadillo-rv.com/ProductDetail.aspx?ProductID=18 , http://www.armadillo-rv.com/ProductDetail.aspx?ProductID=23 , and http://www.armadillo-rv.com/ProductDetail.aspx?ProductID=15 . Just click on the images on the Armadillo product-range page (the second link provided), and you’ll be able to see copious photographs of all Armadillo vehicles.

I provided lots of Armadillo links, because if you can’t read Chinese, you might find their website difficult to navigate. But Google "translate" renders the website reasonably accessible. For instance, check out some great videos of Armadillo vehicles negotiating sand dunes in (what must be) the Taklamakan desert, at http://translate.google.co.uk/translate?hl=en&sl=zh-CN&u=http://www.armadillo-rv.com/&prev=/search%3Fq%3Darmadillo%2Brv%26biw%3D1885%26bih%3D1102 , and click on "Audio/Data".

From a design point of view, let’s just say that the Chinese are “catching up”, and the interiors of many of these Armadillo vehicles are detailed to a level that might leave ActionMobil and UniCAT customers green with envy! My favorite is a really spectacular pop-up at http://www.armadillo-rv.com/ProductDetail.aspx?ProductID=18 . UniCAT, eat your heart out! (Disclosure: I am German/Canadian).

Now all of these large expedition mobile homes follow a standard design format, in which a structurally separate, comparatively “short” cab (less than 3 m in length), is followed by a very long body (7 or 8 m in length), the latter mounted on a 3-point pivoting subframe. In the Zetros, however, the cab itself is also mounted on 3-points – see http://www2.mercedes-benz.co.uk/content/unitedkingdom/mpc/mpc_unitedkingdom_website/en/home_mpc/Unimog/home/unimog_overview/zetros/zetros/technical_data.html and http://www2.mercedes-benz.co.uk/content/media_library/unitedkingdom/mpc_unitedkingdom/Unimog/pdfs/zetros/zetros_brochure.object.Single.File.tmp/Zetros%202011.pdf . And earlier in this thread, a contributor wrote that in a UNIMOG, everything is mounted on separate 3 point subframes – the engine, the cab, the body, everything.

So I was wondering: Could it in principle be possible to change the size-ratios of Cab-to-body, in a very large expedition vehicle?

Imagine instead that in an Armadillo or ActionMobil motorhome (based on a MAN TGS chassis), the Cab were lengthened to 4 or 5 m, and that this "first half" of the vehicle were fully fused with living quarters, as in “fully integrated” motorhomes.

For a visual example of what I have in mind, see for instance The Hymer Starline, a large “fully integrated” German motorhome, in which the front seats can swivel around 180 degrees, and do “double duty” as chairs providing seating at a dining table: http://www.hymer.com/en/ , http://www.hymer.com/en/models/ , http://www.hymer.com/en/models/integrated/hymer-starline/overview.html#.UtE_6HmK05A , http://www.hymer.com/en/models/integrated/hymer-starline/hymer-starline-s/experience.html#.UtFAD3mK05A , http://www.hymer.com/assets/images/modell-2014/hymer-starline-s/impressionen/HY13_BM680S_I_Sitzgruppe_Leder_Kiesel_0.jpg , and
http://www.hymer.com/assets/images/modell-2014/hymer-starline-s/impressionen/HY13_BM680S_I_Sitzgruppe_Leder_Kiesel_1.jpg :

HY13_BM680S_I_Sitzgruppe_Leder_Kiesel_1.jpg

HY13_BM680S_I_Sitzgruppe_Leder_Kiesel_0.jpg

By way of contrast, most expedition motorhomes -- of the sort offered by ActionMobil, UniCAT, Armadillo, et al -- seem to be very space-wasteful, because the seating used for driving never does “double duty” as seating for dining. Instead, the cab remains a separate, short box at the front, and then a second set of seats has to be provided for the camper in the back, for dining.

However, if the cab were lengthened 3, 4, or 5 m, and became the “first half” of the vehicle; and if it were then connected to the second half, also 4 or 5 m long, by an accordion-type “tunnel” located in the middle of the vehicle, then a “fully integrated” design similar to the Hymer might become possible.

Sure, there would still have to be an accordion-type tunnel connecting the front half (4 or 5 m long) and the rear half (4 or 5 m Long) -- an accordion-type tunnel located in the middle of the vehicle. But from a space-usage point of view, these two, roughly equal-length halves would offer design possibilities that the traditional “semi-integrated” or “non-integrated” expedition motorhomes simply do not. In effect, almost all expedition motorhomes designed and sold thus far have been “semi-integrated” or “non-integrated”. The only exceptions might be some expedition-capable van conversions, which one could describe as “fully integrated”.

So the engineering questions here are::

A. Would it be possible to construct an expedition motorhome with a “Cab” and a “Body” of roughly equal length (both of them 4 - 5 m long), both mounted on separate, 3-point pivoting sub-frames, and connected by an accordion-type tunnel in the middle?

B. What would be the engineering challenges of such a design?

C. How big could the accordion-type tunnel located in the middle of the vehicle be? How tall? How wide?

D. And most critically, where would one locate the pivots for the two halves, front and back?


Presumably, if the underlying Chassis were a MAN TGS 8 x 4 (as per the biggest Armadillos), then the front half (call it the "cab") would mount on two points above the first pair of axles, and would have its third pivot located near the middle of the vehicle; while the back half (call it the "camper" or the "body") would mount on two points located above the second pair of axles, at the rear of the vehicle, but again would have its third pivot also located near the middle of the vehicle?

But I am not an engineer, so I really don’t know the answer to this second subset of questions…..

For now, just "bracket" what happens to the engine, which in any case would probably mount separately at the very front, under a "nose" or "bonnet", as per the Zetros off-road truck. As Mercedes has realized, the cab-over-engine design of Euro-style trucks like the MAN TGS might be fine for highway driving, but for off-road driving, cab-over-engine is ergonomic hell (again, see the link to the Zetros PDF above).

So in the design that I am proposing, there might be at least three, separate, 3-point mounts:

(a) the engine, under a bonnet at the very front;
(b) the 4 - 5 m long "cab", or first half of the vehicle;
and
(c) the 4 - 5 m long "body", or second half of the vehicle.

For what it's worth, this also seems to be the mounting format of the Zetros, except that the "cab" of the Zetros is only about 2 m long.


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A bit more about me: I am a student studying Transportation Design at an Art School in England, whose thesis project is -- you guessed it -- designing a very large, experimental, offroad-capable mobile home. So the questions above are really “design possibility” questions. I am curious about what might actually be structurally feasible, from an engineering point of view, in a very large, off-road, expedition-type motorhome.

Many thanks in advance for any and all responses!


Biotect
 

Victorian

Explorer
You made some very good points! I like your thinking :)

I have been "designing" (just for my own pleasure) and building (couple of years at Unicat) Expedition trucks. I also visited many "globetrotter" meetings in europe as I have met many overlanders in Africa over the years and think I got a rough idea of the complexity and challenge of designing the "perfect" expedition truck.
First off, I think 99% of buyers are kind of limited in what kind of money they can spend on a custom build. Therefore, off the shelf trucks are the way to go. In rare cases you may find people that peel out what ever money it takes to get their toy on the road... But even those are limited to the type of base truck they can get their hands on. www.maximog.com
As for the chinese manufacturer: Amazing looking truck! No question. It's crazy what you can do when labour only costs you a fraction of the European products. At Unicat, we only had the best of the best trades people :) And we got payed very well. Quality has it's price! I have to agree on the interior design... They are practical and not build to win a design competition. But the difference is in the details. Open up panels, check out how the waterlines, electrical is routed. You go offroad with a Unicat and you know, that nothing with rattle and break down in the back. Check out this video and pay attention to the flex and abuse the box is taking during the river crossing: http://www.unicat.net/video/GOINGTHERE.WMV You would be blown away after finding out how much attention to detail we put into small things.
Anyhow, I'm not employed their anymore and I'm not a sales rep of Unicat... But I'm still benefiting from what I learned.

Please keep posting about your project!

Andreas
 

Iain_U1250

Explorer
Some very interesting concepts Biotect, in the 90's there were a lot of Unimogs built with large single body. I have no idea about the mounting on the chassis, they were built as tour buses from trips to Cape York, Fraser Island etc, and in those days the roads very bad. Going there was a big adventure for most people.

A friend sent these photos of one in a camp ground in the Northern Territory.

09-07-16_914.jpg09-07-16_913.jpg09-07-16_915.jpg09-07-16_916.jpg09-07-16_917.jpg

I have only seem one of these trucks. it was in a field behind a roadhouse halfway between Cooktown and Cape Tribulation. I could not take any photos as the owner would not let me as he was going to sell it, but it was in such terrible condition ( a few creatures had moved in) and he wanted to fix it up a bit before trying to sell it, all I know is that the box on the truck was very heavy, but it had survived 20 year or more on some of the roughest roads in Australia.

Regarding having the pivot in the middle of the vehicle, and a very large opening. The problem we have in Unimogs is that the chassis is designed to twist, and it twists a lot, 500mm of displacement at the corner of the cab, and getting a concertina to twist is not easy. It flexes easily, but twisting it is a different story, made a square one out of paper and see what happens and how much material you need for relatively small amount of twist and getting it to fold back is an additional problem. The further from the centre of rotation, the more displacement you get. Even the Unicats of the world don't really have a good solution, and reply on door both side to keep out the heat and noise etc. The ones I have seen sag, and drop down into the opening due to the air pressure at higher road speeds.

We spent a fair amount of time and effort getting something we think will work for out pass through, ( see my camper build thread) but may even go back to an accordion model with different layers of material if our current one doesn't perform.

Regarding your thesis, remember that an 8x8 would be very limited as to where it could go, great for deserts, but not much good on smaller roads normal only used by 4x4 and small trucks or "chicken" buses. Defining where you want to go is a very important part of deciding what your expedition truck has to do.
 

ntsqd

Heretic Car Camper
LukeH said:
ntsqd said:
If you insist on having pivots I think that having the longitudinal axis pivot at the rear makes more sense. Put it at the front and you force the frame to rotate the camper box when ever it twists. Put it at the rear and now the frame is free to twist under the camper box..
Why would you want that?
I would put it there because of bending forces in the frame. The greatest Bending Moment is going to be centered between the axles. It makes the most sense to have a degree of freedom aligned with it as close to that point as is reasonably possible. To say that you have no roll control is a gross exaggeration. It is true that this would introduce further compliance, but no control? Get real.

LukeH said:
ntsqd said:
More important than the fore/aft location of the longitudinal axis pivot is the vertical location of this pivot. If it is either above or below the axis that the chassis twists about it will cause some lateral displacement of the camper box. If the other two supports do not have that degree of freedom built into their design some parts will be flexing and distorting if not built heavily enough, and if built heavily enough will be 'working' their attachment to the chassis. None of this is good for longevity.
Almost right. A three point mount with a point too high or low would mean the twisted chassis tries to shorten one of the sides of the triangle. So in theory you are absolutely right. In reality you have overlooked the fact that the chassis has twisted, therefore it is flexible. As a result it's not the triangle that is forced, but the untriangulated chassis that deforms to accomodate the indeformable triangle.
It's something it can do, and does it without problems as the deformation is tiny compared to the huge twist of the rails.
No, exactly right. If the longitudinal axis pivot is on the axis of chassis twist then the only way for the triangle to change would be for the mount/pivot spacing to change. For that to happen any adjacent cross-members would have to shrink or grow, or the rails themselves would have to lengthen or shorten. Given that steel is not perfectly rigid I would expect very subtle deltas. Anyone who designs the pivots without enough compliance to allow for this is very misguided.


As I believe that I've subsequently posted, I've concluded that pivot mounts on a typical ladder frame (I'm excluding Unimogs with that description) are a waste of time. The U.S. military 2.5t and 5t trucks did it the best way IMO. Full rail length contact with the box or bed using spring-loaded mounts. Ideally there would be a layer of Jabroc, Teak, Acetal, or some other low C[SUB]f[/SUB], non cold-flowing material (i.e. NOT PE or PTFE) between the frame and the load.

These are my considered opinions and they are worth what you paid me for them.
 

Goingbush

New member
South African Iveco Daily 4x4 using rear pivoting frame http://www.motorhome-world.com/DiscovererXtreme.htm

below image is a screen shot from their youtube video http://www.youtube.com/watch?v=Y7n-Cl1Vuow


Its a nice build but watching the video Im not sure there is enough chassis flex to warrant the pivot complexity

**********************

On my own Daily I simply used the front factory cup washer spring arraignment with a PE spacer between subframe and factory mount plate


and at the rear , fish plates have been added per VSB document but not shown




below image taken with truck crossed up


note the the gap between bumper and headlight , when level there is no gap, and the amount the box has displaced from the cab.
these pics were during build up before fitting water tanks , jerry cans and another spare went on the back



Ive just clocked 12,000 km , I know its not much but its been shakedown testing including the Darling River Run which was in fine form, lots of corrugations and sandy sections, only a very small amount of low range and a bit of articulation testing. The side door on the box is a very tight fit, even when the truck is crossed up it opens and closes as normal. Not one loose rivet or screw, nothing has bent or moved, I'm confident it will last the distance.



oh, Ive since found some proper corner caps for the box (Thanks Dave)

if interested more on the Truck is in our blog http://www.goingbush.com/iveco.html
 
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LukeH

Adventurer
No, exactly right.
If the longitudinal axis pivot is on the axis of chassis twist then the only way for the triangle to change would be for the mount/pivot spacing to change. For that to happen any adjacent cross-members would have to shrink or grow, or the rails themselves would have to lengthen or shorten.
You are absolutely right. There is no appeal. This point had me worried for years (quite literally) because I couldn't see any way round it.
Then I started working with Renault trucks (= Volvo/Mack)
There is a huge gap between theory and practice.
The situation was put into real terms, on a specific application.
The application I refer to is open C section rolled chassis rails joined by open section traverses riveted into place. No welding as that damages the chassis rails.
That describes the majority of the commercial heavy goods vehicles on and off the road. It does not describe the extremely rigid chassis made by SCAM for Goingbush's magnificent little Daily
This type of chassis is flexible, in pretty much all directions except in the depth of the rails, which is intended for load carrying. On a bare truck it's possible to deform the rails (elastically) just by pulling the truck sideways in the middle of a rail. A fully rigid subframe in triangle or diamond form (as used by the big manifacturers - Unicat etc.) very often doesn't have its centreline pivot in the rotating axis of the chassis because in some cases someone's been inconsiderate enough to put a gearbox, air tanks or other gubbins in the way.
As the chassis twists, it rotates around the excentric center pivot. But the chassis is not triangulated the way the subframe is and the paralellogram of the ladder chassis is actually forced out of alignment.
So you're right, but here's the catch:
It doesn't matter. The rails don't have to shrink or grow, the cross-members flex and the ladder becomes a paralellogram. The chassis is very compliant and all sorts of other forces are misaligning the parallelism of the chassis rails, which are now more like a DNA helix. (Photo to follow)

Given that steel is not perfectly rigid I would expect very subtle deltas. Anyone who designs the pivots without enough compliance to allow for this is very misguided.
Absolute judgement is unnecessary; Kerax specialist vehicles, Kamaz, Unicat, Tartaruga, and many others are clearly "very misguided"
My misguided career has touched Kerax SV, but the others clearly lost their war without my help :)

The U.S. military 2.5t and 5t trucks did it the best way IMO. Full rail length contact with the box or bed using spring-loaded mounts. Ideally there would be a layer of Jabroc, Teak, Acetal, or some other low C[SUB]f[/SUB], non cold-flowing material (i.e. NOT PE or PTFE) between the frame and the load.
The semi-rigid mount has its place, it is not torsion free, the springs transmit some of the torsion to the loadbed. The above mentioned trucks are mainly flatbed, boxes are mounted with dedicated tie-downs. Motorhome boxes are a different animal; if they are subjected to too much torsion the furniture comes apart (been there, done that on a poorly designed old 4x4 Daily). "Too much" torsion is subjective.

Interestingly this brings us back to pivot positioning too. The floppy chassis mentioned is really not capable of transmitting any torsional rigidity for or aft to the lateral stabiliser mounts. They need to be as near to the anti roll bar as possible. Otherwise the roll of the payload "winds up" the chassis before it can exert a reaction force to prevent the payload rolling further. This amounts to 15 degrees of wind in the 5m of free chassis I have.

These are my considered opinions and they are worth what you paid me for them.
:)
Thankfully I have escaped from the automotive industry and I now design bits of satellite; but the above are not my opinions, they are my findings, from time with Renault and from playing with my own truck.
 

mog

Explorer
Full rail length contact with the box or bed using spring-loaded mounts. Ideally there would be a layer of Jabroc, Teak, Acetal, or some other low C[SUB]f[/SUB], non cold-flowing material (i.e. NOT PE or PTFE) between the frame and the load.
What do you think about using 3/8" HDPE (High-density polyethylene) aka: puckboard or greensheet (logging) as the 'spacer' in a spring mounted full rail contact system?
 

LukeH

Adventurer
Wonder if this will work from my phone
The mgvw is 14tonnes, but even unladen the chassis winds up enough to allow one wheel to rise 1.23m before the other starts slipping. A typical heavy goods vehicle is not capable of stopping the load rolling unless it is linked to the stabiliser bar. In which case the latter dictates the angle of the load (unless you have active compensation...watch this space)
 
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