T6M 13.290 Cab / Chassis Scan
MAN TGM 13.290 4 X 4 ( wheel base 4550 mm ) digital image scan of the cabin provides the surface where the fabrication of components such as the pass through , bull bar and roof tyre rack without the need to trial fit. The scanned information is the perfect platform for precise fitting of components.
Torsion Free Sub-Frame
Probably the most critical decision to make is the type of sub-frame ( a pivot frame assembly between the truck chassis and the accommodation module ) to be utilised in the building of a off road 4 X 4 expedition vehicle. The pivot sub-frame is the foundation / platform of your expedition vehicle accommodation module. The sub-framed mechanism employed by Wildplanet Off Road is recommended by MAN and Mercedes-Benz for vehicles that are capable of off-road operation. The “ 4 point “ also known as a diamond shape sub- frame is designed for vehicles with flexible truck chassis for torsionally rigid accommodation modules. For off road use the normal sub-frame used on heavy vehicles is completely in-adequate and would transfer the trucks chassis torsion into the accommodation module causing the module to be comprised. Wildplanet Off Road has developed a special torsion free “ 4 point “ diamond shape sub-frame mechanism specifically for the chassis used for extreme off road performance. The design provides excellent directional stability and ensures ground contact for all four wheels in extreme off road terrain. “The flexibility designed into the trucks chassis must not be restricted.” Wildplanet Off Road commissioned an independent reputable company to carry out a FEA (Finite Element Analysis ) of the design to ensure a torsion free accommodation module. This structural solution then means that the accommodation module has been mounted on a separate “sub-frame that “floats “ or pivots above the trucks chassis. In a nut shell the sub-frame is to be structurally isolated from the trucks twisting chassis to ensure ZERO twist in the sub-frame. Adopting a “4 point “ / “diamond – shaped “ sub-frame will not void the the truck manufactures warranty.
Strengthening The Subframe
A secondary FEA ( Finite Element Analysis ) simulation of the torsion free sub frame design showed strengthening gussets are required where the outer RHS lateral bearers meet the longitudinal RHS chassis main rail members.
The FEA showed the loads from the bottom face of the lateral bearers being transferred into the middle face of the main longitudinal chassis rail.
Taking into account the FEA shows the high stress areas in red.
The still photo of the simulation on the left clearly shows the load being transferred from the lateral bearers into the main chassis rail.
With the introduction of an RHS wedge to create a fully boxed in gusset where lateral and longitudinal members meet, the right hand still photo of the simulation shows the high stress area has been removed.
The complete sub frame will be fabricated using gussets which distribute the loads and adds stiffness to the subframe structure.
The FEA results highlight Wildplanets’ commitment to precision engineering design.
Connection between steel lockers and the torsion free subframe.
Wildplanet commissioned a leading engineering group to carry out a Finite Element Analysis ( FEA ) of the connection between steel lockers and the torsion free subframe.
Two analysis were undertaken.
1. A linear static FEA of the mounting brackets for a series of steel lockers attached to the torsion subframe.
2. A linear static FEA of the subframe supporting the weight of the heaviest locker that houses a 5 KVA Onan generator.( 180 kilograms )
The results of the testing showed stresses experienced in the mounting brackets are below the yield strength of the material up to a 3.16G bump load with was considered adequate for the purpose.
As the Wildplanet 4 X 4 off road vehicle is designed for extreme off road travel it was decided to design the locker to subframe mounting system increasing the bump load by 50% .( 4.5G )
The peak stress in the body subframe remains under material yield for a 4.5 G bump load and surpasses the strength of the mounts.
Owners of a Wilplanet off road motorhome can be assured that every component has been engineered to the highest standard.