just thinking again

[wreckless]

just saw on a mitsubishi add that their new pajero had a monocoque chassis or something, and being curious i wont to know just what monocoque means

[Dino IV]

'mono''coque' means 'one''shell' in French. Unlike the archetype of the horse cart, charriots and classic cars where wooden c.q. steel beams formed a horizontal frame - the chassis - which supported the suspended wheels and the propulsion system as well as the container of cargo and people - the coach-work, the body-work or the 'carrosseria superleggera' - modern cars are built as an tin can which integrates both chassis and bodywork. It's empty inside for cargo, passengers and engine and has a shell on the outside which is chassis and body-work at the same time.

The term monocoque is prone to erosion as purists will say that a monocoque is like a tin can: one shell made of one thing only. Modern cars are made by making numerous canny forms with steel sheet and attaching those together to a structure which makes a body for a car defying the term monocoque. More rightful monocoques are the 'tubs' of F1 cars, which are .. well .. like a carbon bathtub which forms the front half of the cars chassis.

Anyway, by claiming the new Pajero is a moncoque Mitsubishi is only saying their top 4WD is now being built with a regular roadcar bodywork instead of with a metal beam ladder-frame chassis. The latter is still the traditional way of building 4WD as their torsional stiffness characteristics are better suited to off-road dynamics but the current trend is to modernise their design and production methods.

[zefarelly]

in other words . . .peole who buy the ugly things only go to Waitrose in them, and they can make them 'fit for purpose' in monocoque and save money. . . .

[racealign]

sorry that I have to disagree with the ladder chassis being "torsonally stiffer". A ladder type chassis is not as stiff as a monocoque its just phisically stronger and tougher than the monocoque and better suited to going off road and being bashed about. The cabin/body is bolted to the ladder at various points and do offer some increase in stiffness, however . For any structure to be stiff it has to be triangulated or better still pyriamided (if there's such a word).

[pirenzo]

The latter is still the traditional way of building 4WD as their torsional stiffness characteristics are better suited to off-road dynamics

Don't agree with you, agree with race align.

If they were "torsionally stiffer" they would use them in race car design, since torsional stiffness is v important there.

[Jukebox]

Got to agree that most SUV and 4x4s would use the ladder chassis design as it'll blend well with the stiff transverse-leaf springs. But because of it's 2 dimensional structure, the torsional rigidity / stiffness is very much lower than other chassis, especially when dealing with vertical load or bumps. It's an ancient chassis design anyway and mass produced vehicles would go for monocouque as it'll be cheaper and safety elements can be added on easily.

[Dino IV]

A misunderstanding. I didn't note that ladder frames are stiffer, but better suited. If off-road dynamics required stiffer chassis the ladder design would have been dropped long before, no?

[Rhino]

In Land Rovers case with the proper off roader (defender range) you can easily change body types to maximise your market.

[RWC]

I agree with dino.The ladder type chassis is reasonably well suited to offroaders.It can easily flex when such a characteristic is needed.
Of course a monocoque design can be made to suit a 4wd quite well too (and would be enormously usefull for optomising the onroad handling)
Alot of manufacturers still use ladder type chassis becaus there is little need for change/cost to change/&(less and less these days)a ladder type chassis makes it easy to mount rear pickup trays and have good hard points for pulling and winching.
Mostly these days it's just a matter of the cost of changing

[boyracer]

Unless too much beer has addled my brain, I believe the current range of Mitsubishi Pajero has a mono-e-whats-it chassis (at least here in Oz).