threepiece188
New member
I'm not sure if this type of isolator http://www.isolator.com/ has been reviewed in this thread or not so I am showing it here. I't' called a helical cable isolator and it looks interesting to me.
pivoting frames and mounting campers
- Thread starter lehel1
- Start date
LukeH
Adventurer
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.
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 .
*****************************************
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....
*****************************************
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….?
*****************************************
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!
*****************************************
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 :
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.
*****************************************
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
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 .
*****************************************
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....
*****************************************
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….?
*****************************************
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!
*****************************************
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 :
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.
*****************************************
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
Approved Vendor : Total Composites
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
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.
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.
A friend sent these photos of one in a camp ground in the Northern Territory.
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.
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
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
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)
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 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.
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.
tamangel
Adventurer
maybe not specific to this discussion but found this vid showing desert travel and box's pivoting..
https://vimeo.com/63172583
Mike W
******
https://vimeo.com/63172583
Mike W
******
mog
Kodiak Buckaroo
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)
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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biotect
Designer
Ian and Victorian,
Many thanks for your replies to my query, now on the previous page, i.e. page 33. Sorry it has taken me so long to get back to you; other projects intervened.
I'd like to revisit the question of that the earlier post, and perhaps amplify it a bit. If you recall, that question was:
Is a 3-point pivoting sub-frame absolutely necessary? Could we design and construct a box-frame chassis that was torsionally stiff enough, such that it never twists, no matter how irregular the terrain?? Could the vehicle's progressive coil-spring suspension do all the "work" of handling rough terrain, instead?
Ian, you understood the question very well, and thanks again for your response. Thanks in particular for your explanation regarding the Unimogs, which have a chassis that is deliberately designed to twist, a lot. And Victorian, many thanks for your wise, prudent comments regarding the constraints motivating most buyers of expedition motorhomes. Experimentation costs money and time, and most buyers have neither in excess.
You both understood my question, but perhaps many on the forum did not? Even so, I really do want to know whether a "torsion free" chassis -- of the sort that MAN advertises for the SX 45 -- is realistically possible. So to make my question clear to others, below I provide some additional background information, in the first two sections.
*****************************************
1. MAN TGS
Here is some background for those who might not be familiar with the very large, “8 x 8”, expedition motorhome market segment.
MAN Gmbh, a truck manufacturer based in Austria, makes most of the truck-chassis used by fabricators of the largest overland motorhomes, i.e. fabricators like Action-Mobil, UniCat, Armadillo, etc. Very large expedition motorhomes will typically be mounted on a MAN TGA or TGS chassis, of the kind used for off-road construction, in 4 x 4, 6 x 6, 8 x 4, and even 8 x 8 variants – see http://www.mantruckandbus.hu/man/media/migrated/doc/mn_hu_1/TGS_broura.pdf , http://www.truck.man.eu/global/en/b...-duty-transport/tgs-ww/overview/Overview.html , http://www.mantruckandbus.com/man/media/migrated/doc/master_1/Construction_site_vehicles__en_.pdf , http://www.man-bodybuilder.co.uk/specs/pdf/tgs/TGS 8x4 Heavy Duty Tipper.pdf , http://www.euro6ready.com/assets/pdf/TGS/TGS_8x4_Heavy Duty Tipper_Sept_2013.pdf , http://atstrucks.co.nz/uploads/specs/TGS_8x8Tipper.pdf , and http://www.man.com.au/truck-range/tgs-range/tgs-8x8-2 /.
Over the last century MAN has built up a reputation for making rock-solid, very reliable trucks that can function well in off-road conditions like construction sites, or mining operations in the Third World..... And if MAN construction trucks can withstand the rigors of Third-World mining, then -- or so companies like ActionMobil, UniCat, and Armadillo reason -- such trucks can certainly withstand the rigors of off-road (or more like "bad-road") expedition travel.
For examples of some very large, expedition motorhomes based on a MAN chassis, see:
(1) ActionMobil, at http://www.actionmobil.com/en/4-axle/specials , http://www.actionmobil.com/en/4-axle/interior-design , http://www.actionmobil.com/en/3-axle/globecruiser , and http://www.actionmobil.com/en/3-axle/atacama ;
(2) UniCat, at http://www.unicat.net/en/info/MXXL24AH.php , http://www.unicat.net/pdf/UNICAT-MXXL24AH-MAN8x8-en-es.pdf , http://www.unicat.net/en/info/EX70HDQ-MANTGA6x6.php , http://www.unicat.net/en/pics/EX70HDQ-MANTGA6x6-2.php , http://www.unicat.net/en/info/EX63HDSC-MANTGA6x6.php , http://www.unicat.net/en/pics/EX63HDSC-MANTGA6x6-2.php , http://www.unicat.net/en/info/EX70HD2M-MANTGA6x6.php , http://www.unicat.net/en/pics/EX70HD2M-MANTGA6x6-2.php , http://www.unicat.net/en/info/EX63HDM-MANTGA6x6.php , http://www.unicat.net/en/pics/EX63HDM-MANTGA6x6-2.php , http://www.unicat.net/en/info/EX58HD-MANTGA4x4.php , http://www.unicat.net/en/info/EX58HD-MANTGA4x4.php , and http://www.unicat.net/en/info/EX45HD-UnimogU5000.php ;
and
(3) Armadillo, a newer Chinese company, at http://www.armadillo-rv.com , http://www.armadillo-rv.com/Product.aspx or http://translate.googleusercontent....t.aspx&usg=ALkJrhggsDoN3MnNoJEUh-EIgFM01UIHFg ; http://www.armadillo-rv.com/ProductDetail.aspx?ProductID=4 , http://www.armadillo-rv.com/ProductImageShow.aspx?ProductID=4&PhotoClassID=1 , http://www.armadillo-rv.com/ProductImageShow.aspx?ProductID=4&PhotoClassID=3 , http://www.armadillo-rv.com/ProductDetail.aspx?ProductID=7 , http://www.armadillo-rv.com/ProductImageShow.aspx?ProductID=7&PhotoClassID=1 , http://www.armadillo-rv.com/ProductImageShow.aspx?ProductID=7&PhotoClassID=3 , http://www.armadillo-rv.com/ProductDetail.aspx?ProductID=22 , http://www.armadillo-rv.com/ProductImageShow.aspx?ProductID=22&PhotoClassID=1 , and http://www.armadillo-rv.com/ProductImageShow.aspx?ProductID=22&PhotoClassID=3 .
See in particular Armadillo’s rendition of the UniCat-style pop-up, in a 6 x 6 TGA version, at http://www.armadillo-rv.com/ProductDetail.aspx?ProductID=18 , http://www.armadillo-rv.com/ProductImageShow.aspx?ProductID=18&PhotoClassID=1 , http://www.armadillo-rv.com/ProductImageShow.aspx?ProductID=18&PhotoClassID=3 , or http://translate.googleusercontent....tID=18&usg=ALkJrhidd0y_mOes-sMSggoNvbYNK-_Sww . And for some multimedia videoclips of Armadillos in action in the Mongolian desert, see http://www.armadillo-rv.com/Multimedia.aspx .
*****************************************
2. MAN Military
Now as many regulars on the “Overland Portal” perhaps already know, MAN Gmbh has a military division, one that produces off-road military trucks that are widely used by NATO and other armed forces. This is a natural extension of MAN's experience fabricating off-road construction trucks for harsh conditions. As MAN has stated on its military-division website, the expertise it gains via the TGA and TGS line of construction trucks goes into its military vehicles, and so too vica-versa. So a MAN 8 x 8 military truck is, in a sense, a TGA or TGS "in disguise".
Years ago MAN's military trucks were known as the “KAT” series, and Actionmobil even converted a former KAT 8 x 8 into a motorhome for a sheikh – see http://www.military-today.com/trucks/man_kat1_8x8.htm and http://actionmobil.com/en/4-axle/desert-challenger .
However, at present, the line-up of MAN’s off-road military trucks is known as the “HX” and “SX” series – see http://www.military-today.com/trucks/man_sx45.htm , http://www.military-today.com/trucks/man_sx44.htm , http://www.military-today.com/trucks/man_hx77.htm , and http://www.military-today.com/trucks/man_hx58.htm . These MAN military trucks now completely dominate the market in Europe, the UK, Australia, and New Zealand – see http://www.defenseindustrydaily.com/british-tactical-truck-order-rises-to-gbp-135b-02409/ , http://www.commercialmotor.com/latest-news/man-fleet-for-the-mod- , http://www.army.mod.uk/documents/general/285986_ARMY_VEHICLESEQUIPMENT_V12.PDF_web.pdf (page 39), http://www.armyvehicles.dk/man32430.htm , http://www.rheinmetall.com/en/rheinmetall_ag/press/news/archive_2013/news_details_6_2688.php , and http://www.armyrecognition.com/may_...tary_trucks_from_rheinmetall_man_1605132.html .
The Mercedes Benz Zetros, by way of comparison, is sold mostly to the Bundesweher (the German military), and various armies in Arab countries – see http://www.battle-technology.com/exhibitions.asp?key=653 . As the last link just cited makes clear, over the last few years MAN has delivered literally thousands of new HX and SX vehicles to forces in Europe, the UK, Australia, and New Zealand.
It’s then rather curious that, 3 years ago, it was very easy to find information about the HX and SX on-line, via MAN’s military website, but now it's almost impossible. In the intervening years, MAN’s military manufacturing operations have been taken over by “Reinmetall AG”, whose relationship to MAN is a bit unclear – see http://www.rheinmetall.com/en/rheinmetall_ag/group/index.php , http://en.wikipedia.org/wiki/Rheinmetall , and http://en.wikipedia.org/wiki/Rheinmetall_MAN_Military_Vehicles , and http://www.rheinmetall-defence.com/...bsidiaries/rheinmetall_man_military_vehicles/ .
The bottom line is that, if you hope to find significant information about the HX or SX series of MAN military trucks on the current Rheinmetall website, you will be disappointed – see http://www.rheinmetall-defence.com/...cts/vehicle_systems/military_trucks/index.php . Whereas when the company was still “MAN Military”, a PDF brochure detailing HX and SX capabilities – a brochure titled “The Mobility Elite” – was always available online. It’s this particular brochure that I need to reference, in order to make my question clear.
In the previous post I gave a link to the brochure that was then still working, but that link has since expired. Here is another link, to SCRIBD, which I hope will last longer -- http://www.scribd.com/doc/17296072/The-Mobility-Elite .
But just in case this SCRIBD link also does not survive, below I've pasted jpg copies of the relevant pages in the PDF.
*****************************************
3. Is a 3-Point Pivoting Sub-Frame Necessary?
Is 3-point pivoting sub-frame absolutely necessary? That’s the question I asked a few months ago.
According to MAN’s “Mobility Elite” brochure, perhaps not. The following are snapshots from the first few pages of the PDF.
The text in the last snapshot is what got me thinking. Here MAN Military writes:
*****************************************
"100 % torsional stiffness – the box-type frame.
The extremely torsion resistant box frame with hollow longitudinal members and welded tubular cross members put the SX in a class of its own. With this design the suspension absorbs even extreme terrain irregularities. The desired consequence: the body remains unaffected even during fast off-road driving.
Coil-sprung high mobility – the suspension.
The secret of its high mobility is the progressive coil spring suspension for extremely long spring travel which permits rapid adjustment to the terrain. Additional shock absorbers with integrated dampers on the rear axle are available on request.
A special highlight is the optional hydro-pneumatic suspension with integrated, regulated load-dependent shock absorbers and extremely long spring travel for top driving stability under the toughest conditions. It is equipped with a height adjustment and can be locked in any position."
*****************************************
Should we take this description at face value? Is this just hype, or is it in fact possible to deliver what MAN Military promises here?
Does it strike those on this forum as feasible to build a frame that is so stiff, that it is 100 % torsion-free, as MAN promises? With a progressive coil-spring suspension that absorbs all “terrain irregularities”, even the most extreme ones? Such that any body placed on top will remain “unaffected, even during fast off-road driving”? If you compare the pictures of the HX and the SX vehicles above, for instance, it does seem that the box-frame in the SX is far more robust. And note that MAN only makes this claim only for the SX-45; it does not make this claim for the HX series.
Also note that MAN repeats this claim in the PDF. In the third-to-last page from the series posted above, MAN writes about the SX-45:
"With its unique off-road capabilities and torsional rigidity the SX sets the benchmark in mobility – high performance off-road. It can even get through where only tracked vehicles normally have the capability. The SX is the leader in its class, and either the 3- or 4-axle vehicle is predestined for the transport of high-class, complex and sensitive bodies, ideal as a system and weapon carrier for tactical missions......"
Now those who have been following this thread will realize just how significant a claim this is. MAN is saying that the SX 45 can carry "complex, sensitive bodies" without any need for a 3-point, pivoting sub-frame, precisely because its box-frame proves so torsionally rigid.
*****************************************
4. A Real Puzzle
But if this is true, then why hasn't this technology yet "spilled over" from the military side, towards the commercial end of things? Presumably MAN military and MAN commercial do talk to each other? And presumably someone might have seen the utility of a completely torsion-free, "high mobility" box-frame, for makers of very large, expedition-style motorhomes, like ActionMobil, UniCat, and Armadillo?
SX-45 technology has been around for a while: MAN started delivering the first vehicles, it seems, from roughly 2005 onwards. So why are ActionMobil, UniCat, and Armadillo still building their 6 x 6 and 8 x 8 "specials", on frames that twist? If you take a look at some of the videos of 6 x 6 and 8 x 8 vehicles on the ActionMobil and Armadillo websites, you'll see that when they go over rough terrain, as one might expect the cab goes one way, and the body another.... I don't know whether this potential to "twist" was already built into the TGA or TGS construction-vehicle chassis, as delivered from MAN's factory. However it arises, it is certainly a feature of even the largest 8 x 8 expedition motorhomes. It's also quite clear that all of them are still being mounted on 3-point pivoting sub-frames. But given the existence of a potential SX-45-style solution, why hasn't any fabricator yet adopted this as an alternative?
Something here does not quite "fit", and I am not sure what it is. I tried calling up Rheinmettal-MAN a number of times, but just got the run-around, and no-one I talked to seemed to understand my question, let alone provide a straight answer. So this thread seemed like the perfect place to post this puzzle.
Here's hoping that, this time around, many more will understand the query...
But again, Ian and Victorian, many thanks to you both for your responses.
All best wishes,
Biotect
Many thanks for your replies to my query, now on the previous page, i.e. page 33. Sorry it has taken me so long to get back to you; other projects intervened.
I'd like to revisit the question of that the earlier post, and perhaps amplify it a bit. If you recall, that question was:
Is a 3-point pivoting sub-frame absolutely necessary? Could we design and construct a box-frame chassis that was torsionally stiff enough, such that it never twists, no matter how irregular the terrain?? Could the vehicle's progressive coil-spring suspension do all the "work" of handling rough terrain, instead?
Ian, you understood the question very well, and thanks again for your response. Thanks in particular for your explanation regarding the Unimogs, which have a chassis that is deliberately designed to twist, a lot. And Victorian, many thanks for your wise, prudent comments regarding the constraints motivating most buyers of expedition motorhomes. Experimentation costs money and time, and most buyers have neither in excess.
You both understood my question, but perhaps many on the forum did not? Even so, I really do want to know whether a "torsion free" chassis -- of the sort that MAN advertises for the SX 45 -- is realistically possible. So to make my question clear to others, below I provide some additional background information, in the first two sections.
*****************************************
1. MAN TGS
Here is some background for those who might not be familiar with the very large, “8 x 8”, expedition motorhome market segment.
MAN Gmbh, a truck manufacturer based in Austria, makes most of the truck-chassis used by fabricators of the largest overland motorhomes, i.e. fabricators like Action-Mobil, UniCat, Armadillo, etc. Very large expedition motorhomes will typically be mounted on a MAN TGA or TGS chassis, of the kind used for off-road construction, in 4 x 4, 6 x 6, 8 x 4, and even 8 x 8 variants – see http://www.mantruckandbus.hu/man/media/migrated/doc/mn_hu_1/TGS_broura.pdf , http://www.truck.man.eu/global/en/b...-duty-transport/tgs-ww/overview/Overview.html , http://www.mantruckandbus.com/man/media/migrated/doc/master_1/Construction_site_vehicles__en_.pdf , http://www.man-bodybuilder.co.uk/specs/pdf/tgs/TGS 8x4 Heavy Duty Tipper.pdf , http://www.euro6ready.com/assets/pdf/TGS/TGS_8x4_Heavy Duty Tipper_Sept_2013.pdf , http://atstrucks.co.nz/uploads/specs/TGS_8x8Tipper.pdf , and http://www.man.com.au/truck-range/tgs-range/tgs-8x8-2 /.
Over the last century MAN has built up a reputation for making rock-solid, very reliable trucks that can function well in off-road conditions like construction sites, or mining operations in the Third World..... And if MAN construction trucks can withstand the rigors of Third-World mining, then -- or so companies like ActionMobil, UniCat, and Armadillo reason -- such trucks can certainly withstand the rigors of off-road (or more like "bad-road") expedition travel.
For examples of some very large, expedition motorhomes based on a MAN chassis, see:
(1) ActionMobil, at http://www.actionmobil.com/en/4-axle/specials , http://www.actionmobil.com/en/4-axle/interior-design , http://www.actionmobil.com/en/3-axle/globecruiser , and http://www.actionmobil.com/en/3-axle/atacama ;
(2) UniCat, at http://www.unicat.net/en/info/MXXL24AH.php , http://www.unicat.net/pdf/UNICAT-MXXL24AH-MAN8x8-en-es.pdf , http://www.unicat.net/en/info/EX70HDQ-MANTGA6x6.php , http://www.unicat.net/en/pics/EX70HDQ-MANTGA6x6-2.php , http://www.unicat.net/en/info/EX63HDSC-MANTGA6x6.php , http://www.unicat.net/en/pics/EX63HDSC-MANTGA6x6-2.php , http://www.unicat.net/en/info/EX70HD2M-MANTGA6x6.php , http://www.unicat.net/en/pics/EX70HD2M-MANTGA6x6-2.php , http://www.unicat.net/en/info/EX63HDM-MANTGA6x6.php , http://www.unicat.net/en/pics/EX63HDM-MANTGA6x6-2.php , http://www.unicat.net/en/info/EX58HD-MANTGA4x4.php , http://www.unicat.net/en/info/EX58HD-MANTGA4x4.php , and http://www.unicat.net/en/info/EX45HD-UnimogU5000.php ;
and
(3) Armadillo, a newer Chinese company, at http://www.armadillo-rv.com , http://www.armadillo-rv.com/Product.aspx or http://translate.googleusercontent....t.aspx&usg=ALkJrhggsDoN3MnNoJEUh-EIgFM01UIHFg ; http://www.armadillo-rv.com/ProductDetail.aspx?ProductID=4 , http://www.armadillo-rv.com/ProductImageShow.aspx?ProductID=4&PhotoClassID=1 , http://www.armadillo-rv.com/ProductImageShow.aspx?ProductID=4&PhotoClassID=3 , http://www.armadillo-rv.com/ProductDetail.aspx?ProductID=7 , http://www.armadillo-rv.com/ProductImageShow.aspx?ProductID=7&PhotoClassID=1 , http://www.armadillo-rv.com/ProductImageShow.aspx?ProductID=7&PhotoClassID=3 , http://www.armadillo-rv.com/ProductDetail.aspx?ProductID=22 , http://www.armadillo-rv.com/ProductImageShow.aspx?ProductID=22&PhotoClassID=1 , and http://www.armadillo-rv.com/ProductImageShow.aspx?ProductID=22&PhotoClassID=3 .
See in particular Armadillo’s rendition of the UniCat-style pop-up, in a 6 x 6 TGA version, at http://www.armadillo-rv.com/ProductDetail.aspx?ProductID=18 , http://www.armadillo-rv.com/ProductImageShow.aspx?ProductID=18&PhotoClassID=1 , http://www.armadillo-rv.com/ProductImageShow.aspx?ProductID=18&PhotoClassID=3 , or http://translate.googleusercontent....tID=18&usg=ALkJrhidd0y_mOes-sMSggoNvbYNK-_Sww . And for some multimedia videoclips of Armadillos in action in the Mongolian desert, see http://www.armadillo-rv.com/Multimedia.aspx .
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2. MAN Military
Now as many regulars on the “Overland Portal” perhaps already know, MAN Gmbh has a military division, one that produces off-road military trucks that are widely used by NATO and other armed forces. This is a natural extension of MAN's experience fabricating off-road construction trucks for harsh conditions. As MAN has stated on its military-division website, the expertise it gains via the TGA and TGS line of construction trucks goes into its military vehicles, and so too vica-versa. So a MAN 8 x 8 military truck is, in a sense, a TGA or TGS "in disguise".
Years ago MAN's military trucks were known as the “KAT” series, and Actionmobil even converted a former KAT 8 x 8 into a motorhome for a sheikh – see http://www.military-today.com/trucks/man_kat1_8x8.htm and http://actionmobil.com/en/4-axle/desert-challenger .
However, at present, the line-up of MAN’s off-road military trucks is known as the “HX” and “SX” series – see http://www.military-today.com/trucks/man_sx45.htm , http://www.military-today.com/trucks/man_sx44.htm , http://www.military-today.com/trucks/man_hx77.htm , and http://www.military-today.com/trucks/man_hx58.htm . These MAN military trucks now completely dominate the market in Europe, the UK, Australia, and New Zealand – see http://www.defenseindustrydaily.com/british-tactical-truck-order-rises-to-gbp-135b-02409/ , http://www.commercialmotor.com/latest-news/man-fleet-for-the-mod- , http://www.army.mod.uk/documents/general/285986_ARMY_VEHICLESEQUIPMENT_V12.PDF_web.pdf (page 39), http://www.armyvehicles.dk/man32430.htm , http://www.rheinmetall.com/en/rheinmetall_ag/press/news/archive_2013/news_details_6_2688.php , and http://www.armyrecognition.com/may_...tary_trucks_from_rheinmetall_man_1605132.html .
The Mercedes Benz Zetros, by way of comparison, is sold mostly to the Bundesweher (the German military), and various armies in Arab countries – see http://www.battle-technology.com/exhibitions.asp?key=653 . As the last link just cited makes clear, over the last few years MAN has delivered literally thousands of new HX and SX vehicles to forces in Europe, the UK, Australia, and New Zealand.
It’s then rather curious that, 3 years ago, it was very easy to find information about the HX and SX on-line, via MAN’s military website, but now it's almost impossible. In the intervening years, MAN’s military manufacturing operations have been taken over by “Reinmetall AG”, whose relationship to MAN is a bit unclear – see http://www.rheinmetall.com/en/rheinmetall_ag/group/index.php , http://en.wikipedia.org/wiki/Rheinmetall , and http://en.wikipedia.org/wiki/Rheinmetall_MAN_Military_Vehicles , and http://www.rheinmetall-defence.com/...bsidiaries/rheinmetall_man_military_vehicles/ .
The bottom line is that, if you hope to find significant information about the HX or SX series of MAN military trucks on the current Rheinmetall website, you will be disappointed – see http://www.rheinmetall-defence.com/...cts/vehicle_systems/military_trucks/index.php . Whereas when the company was still “MAN Military”, a PDF brochure detailing HX and SX capabilities – a brochure titled “The Mobility Elite” – was always available online. It’s this particular brochure that I need to reference, in order to make my question clear.
In the previous post I gave a link to the brochure that was then still working, but that link has since expired. Here is another link, to SCRIBD, which I hope will last longer -- http://www.scribd.com/doc/17296072/The-Mobility-Elite .
But just in case this SCRIBD link also does not survive, below I've pasted jpg copies of the relevant pages in the PDF.
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3. Is a 3-Point Pivoting Sub-Frame Necessary?
Is 3-point pivoting sub-frame absolutely necessary? That’s the question I asked a few months ago.
According to MAN’s “Mobility Elite” brochure, perhaps not. The following are snapshots from the first few pages of the PDF.
The text in the last snapshot is what got me thinking. Here MAN Military writes:
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"100 % torsional stiffness – the box-type frame.
The extremely torsion resistant box frame with hollow longitudinal members and welded tubular cross members put the SX in a class of its own. With this design the suspension absorbs even extreme terrain irregularities. The desired consequence: the body remains unaffected even during fast off-road driving.
Coil-sprung high mobility – the suspension.
The secret of its high mobility is the progressive coil spring suspension for extremely long spring travel which permits rapid adjustment to the terrain. Additional shock absorbers with integrated dampers on the rear axle are available on request.
A special highlight is the optional hydro-pneumatic suspension with integrated, regulated load-dependent shock absorbers and extremely long spring travel for top driving stability under the toughest conditions. It is equipped with a height adjustment and can be locked in any position."
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Should we take this description at face value? Is this just hype, or is it in fact possible to deliver what MAN Military promises here?
Does it strike those on this forum as feasible to build a frame that is so stiff, that it is 100 % torsion-free, as MAN promises? With a progressive coil-spring suspension that absorbs all “terrain irregularities”, even the most extreme ones? Such that any body placed on top will remain “unaffected, even during fast off-road driving”? If you compare the pictures of the HX and the SX vehicles above, for instance, it does seem that the box-frame in the SX is far more robust. And note that MAN only makes this claim only for the SX-45; it does not make this claim for the HX series.
Also note that MAN repeats this claim in the PDF. In the third-to-last page from the series posted above, MAN writes about the SX-45:
"With its unique off-road capabilities and torsional rigidity the SX sets the benchmark in mobility – high performance off-road. It can even get through where only tracked vehicles normally have the capability. The SX is the leader in its class, and either the 3- or 4-axle vehicle is predestined for the transport of high-class, complex and sensitive bodies, ideal as a system and weapon carrier for tactical missions......"
Now those who have been following this thread will realize just how significant a claim this is. MAN is saying that the SX 45 can carry "complex, sensitive bodies" without any need for a 3-point, pivoting sub-frame, precisely because its box-frame proves so torsionally rigid.
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4. A Real Puzzle
But if this is true, then why hasn't this technology yet "spilled over" from the military side, towards the commercial end of things? Presumably MAN military and MAN commercial do talk to each other? And presumably someone might have seen the utility of a completely torsion-free, "high mobility" box-frame, for makers of very large, expedition-style motorhomes, like ActionMobil, UniCat, and Armadillo?
SX-45 technology has been around for a while: MAN started delivering the first vehicles, it seems, from roughly 2005 onwards. So why are ActionMobil, UniCat, and Armadillo still building their 6 x 6 and 8 x 8 "specials", on frames that twist? If you take a look at some of the videos of 6 x 6 and 8 x 8 vehicles on the ActionMobil and Armadillo websites, you'll see that when they go over rough terrain, as one might expect the cab goes one way, and the body another.... I don't know whether this potential to "twist" was already built into the TGA or TGS construction-vehicle chassis, as delivered from MAN's factory. However it arises, it is certainly a feature of even the largest 8 x 8 expedition motorhomes. It's also quite clear that all of them are still being mounted on 3-point pivoting sub-frames. But given the existence of a potential SX-45-style solution, why hasn't any fabricator yet adopted this as an alternative?
Something here does not quite "fit", and I am not sure what it is. I tried calling up Rheinmettal-MAN a number of times, but just got the run-around, and no-one I talked to seemed to understand my question, let alone provide a straight answer. So this thread seemed like the perfect place to post this puzzle.
Here's hoping that, this time around, many more will understand the query...
But again, Ian and Victorian, many thanks to you both for your responses.
All best wishes,
Biotect
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biotect
Designer
Hi ntsqd,
Interesting response. So there is an engineering distinction between “flex” versus visible “twist”? I am not an engineer, but can imagine that there might be such a distinction.
In effect you seem to be saying that perhaps the MAN brochure is not all hype, and it might in principle be possible to create a vehicle that has
You also wrote some interesting things about mounting payloads. But here I wonder whether the system you envision would prove applicable to all the different kinds of payload that the SX45 has been fitted to carry? The last page of the "Mobile Elite" brochure has a few schematics of the possibilities: missile system carrier, bridgelayer, system cabin…..
The British army, for instance, just received delivery of hundreds of specialized 8 x 8 “recovery” vehicles that have mounted cranes. These kinds of things, presumably, would have to be attached to the chassis in a rather “fixed” sort of way?
Or consider the Rosenbauer Panther, an ARFF or “Aircraft Rescue and Fire Fighting Vehicle”. The Panther is basically an SX-45 8x8 specially fitted with a 1200 HP marine diesel mounted in the rear, and carries thousands of gallons of fire-suppressant foam – see http://de.wikipedia.org/wiki/Rosenbauer_Panther , http://www.rosenbauer.com/en/rosenbauer-world/hauptnavigation/products/arff-vehicles/panther.html , http://en.wikipedia.org/wiki/Aircraft_rescue_and_firefighting , http://www.rosenbauer.com/fileadmin...ospekte low/Prospekt_PANTHER_D_gesamt low.pdf , http://www.rosenbauer.com/fileadmin... - STINGER/HRET Stinger EN_2012-09-06 low.pdf . The Panther has to be very fast, hence 1200 HP, and it has to be an 8 x 8, just in case a plane flies past the runway and crashes in the trees.
Here again the Panther's "payload", if you will, seems attached to the chassis in a fairly "fixed" sort of way. But granted, on a daily basis, the Panther does not do all that much off-road driving…..
I am only asking this question because it seems standard wisdom in the Expedition industry that, for larger vehicles, a 3-point pivoting sub-frame is necessary. But then I came across the MAN "Mobile Elite” brochure, which seems to advertise the SX-45 as not needing anything of the kind.
All best wishes,
Biotect
PS -- Just one practical query. I am still new to the Expedition Portal. How might one upload photographs in such a way that potentially anyone could see them, and not just members who are logged-on? Some of the uploaded images in these threads have a kind of "privacy filter" that prevents outsiders seeing them, while others do not. Mine at present seem to be filtered, but I would like to take the filtering off.
Interesting response. So there is an engineering distinction between “flex” versus visible “twist”? I am not an engineer, but can imagine that there might be such a distinction.
In effect you seem to be saying that perhaps the MAN brochure is not all hype, and it might in principle be possible to create a vehicle that has
You also wrote some interesting things about mounting payloads. But here I wonder whether the system you envision would prove applicable to all the different kinds of payload that the SX45 has been fitted to carry? The last page of the "Mobile Elite" brochure has a few schematics of the possibilities: missile system carrier, bridgelayer, system cabin…..
The British army, for instance, just received delivery of hundreds of specialized 8 x 8 “recovery” vehicles that have mounted cranes. These kinds of things, presumably, would have to be attached to the chassis in a rather “fixed” sort of way?
Or consider the Rosenbauer Panther, an ARFF or “Aircraft Rescue and Fire Fighting Vehicle”. The Panther is basically an SX-45 8x8 specially fitted with a 1200 HP marine diesel mounted in the rear, and carries thousands of gallons of fire-suppressant foam – see http://de.wikipedia.org/wiki/Rosenbauer_Panther , http://www.rosenbauer.com/en/rosenbauer-world/hauptnavigation/products/arff-vehicles/panther.html , http://en.wikipedia.org/wiki/Aircraft_rescue_and_firefighting , http://www.rosenbauer.com/fileadmin...ospekte low/Prospekt_PANTHER_D_gesamt low.pdf , http://www.rosenbauer.com/fileadmin... - STINGER/HRET Stinger EN_2012-09-06 low.pdf . The Panther has to be very fast, hence 1200 HP, and it has to be an 8 x 8, just in case a plane flies past the runway and crashes in the trees.
Here again the Panther's "payload", if you will, seems attached to the chassis in a fairly "fixed" sort of way. But granted, on a daily basis, the Panther does not do all that much off-road driving…..
I am only asking this question because it seems standard wisdom in the Expedition industry that, for larger vehicles, a 3-point pivoting sub-frame is necessary. But then I came across the MAN "Mobile Elite” brochure, which seems to advertise the SX-45 as not needing anything of the kind.
All best wishes,
Biotect
PS -- Just one practical query. I am still new to the Expedition Portal. How might one upload photographs in such a way that potentially anyone could see them, and not just members who are logged-on? Some of the uploaded images in these threads have a kind of "privacy filter" that prevents outsiders seeing them, while others do not. Mine at present seem to be filtered, but I would like to take the filtering off.
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LukeH
Adventurer
Absolutely
If I may rephrase so you don't contradict your previous affirmation: torsionally stiff enough so that the twist caused by the forces that act on it is not great enough to damage the payload?
My issue with the semi-rigid mount is that as the frame twists it compresses the springs which in turn pull on one or other corner of the payload. It's not torsion free, it just reduces the stiffening effect the payload has on the chassis (see your point below), and reduces the twist the chassis exerts on the payload.
For many applications this is sufficient, as it is a compromise (economical, space, engineering effort etc.) that reduces the transmission from chassis to payload to a tolerable level; for a given payload.
Some payloads cannot even tolerate that, and I personally wouldn't take the risk for an accomodation module. Many do and it works for them, so that is why I reiterate that it is my personal choice not to take that risk.
Agreed
....
Goingbush
New member
Point in case
http://www.vertikal.net/en/news/story/11794/
Landrover have a very stiff chassis design, but still flex , as evident by the doors on a Station wagon becoming stiff to open and close when the axles are fully articulated.
When you mount a rigid subframe (load) to a chassis that needs to flex, something has to give.
http://www.vertikal.net/en/news/story/11794/
Landrover have a very stiff chassis design, but still flex , as evident by the doors on a Station wagon becoming stiff to open and close when the axles are fully articulated.
When you mount a rigid subframe (load) to a chassis that needs to flex, something has to give.