I have eagerly followed all the postings in Expedition Trucks etc. that I can find and read all the info. available on Unicat, Bi-Mobil etc with regard to "torsion free mounting" and decided it was absolutely necessary to employ this technique! If you need convincing just watch the chassis/body displacement in any of the action videos for these types of vehicles.
As an aside again - I enquired of the builder of a "professionally" locally built motorhome body - on an 18T 4WD Mercedes chassis what type of mounting system they used. I was informed that the chassis was exceptionally strong and didn't need this type of mounting! Somebody is in for a $435,000 disappointment!
In our local system this will again need engineering certification and licensing authority approval so - once more into the regulations.
An additional section suggests that when the mounting does not distribute the load evenly along the chassis rails, as is the case with this type of mounting, then the main mounting points should be as close to the rear suspension as practicable.
I have only seen one mention of four-point mounting in the discussion groups previously and thought it might be a little too complicated, but on further reflection I believe it has the following advantages :
1) The lateral mounting points directly in line with the rear wheels may allow the body to be mounted lower as room only needs to allowed for suspension movement, body movement will be restrained at this point.
2) Four points allow the body to be constructed without needing to be quite so strong as it is supported at three points along its length (3 point construction only supports at two places longitudinally).
The following photos show the essential components chosen to effect this type of construction. These pieces will make one of the four mounting points. They were selected from the central pivot point of a "walking beam" suspension system for a 30T trailer. As the body for Suz can weigh no more than 6.5T and there will be four of them - I think they will do the job, however they will need the inevitable "engineering compliance certificate".
Disassembled - note the 300mm rule in the foreground. The ground bolt is 50.8mm diam. and 220mm long.
Partially assembled - the centre section will be attached to the chassis and the outer two sections to the body when fully assembled.
Another interesting aside...
My last business was as a manufacturer of components just like this. In fact I made these sleeves which go over the rubber cones as these pieces are normally part of the truck/trailer suspension brackets and would be convoluted castings suitable for a particular vehicle.
I did NOT make the ground bolt which cost $36 (imported from China) or the rubber cones $6 (again imported from China) - it's one of the reasons I decided to retire.
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