I saw a disco in this month's 4wd monthly that had a very interesting idea.
The diff housings (front and rear) had a prop shaft weled to them at about their pivot point. These prop shafts were connected to a centre diff that was fixed to the body. This meant that the front and rear could articulate in opposite directions, and the body would always stay at a fixed angle 1/2 way between the two. It would also mean that the body could not lean in relation to the axle. It's like the ultimate swaybar.
Does this make description any sense?
His original idea was to then run a singel centre airspring for the rear axle, as the rotational control would be through this centre diff off the front axle.
I imagine this system is known by a name and he didn't just invent it. Has anyone heard of it before?
Thanx
Paul
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Diff Housings connected by diff as anti-sway measure
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Diff Housings connected by diff as anti-sway measure
Lexus LX470 - hrrm Winter Tyres
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Gone - 3L Surf
Someone like Isuzurover, Nick in the Falklands or Daddylonglegs would probably have more to say on this, but here is my little take on it.
Mechanically forced articulation was first devised in a recreational off road vehicle by Soni Honneger (sp?) in about 1997. Soni, based in Arkansas, is a Swiss national who migrated to the us and set up a company called recovery engineering, looking after projects like pulling derailed rail cars out of swamps etc. However, he also is an avid 4WDer and a fan of the military aesthetic, he built a couple of cool military projects - The "War Wagon" a dodge ram pickup on 40" tyres, and the "slickrock spider" a coil converted flatfender.
Around 1996 or so, he was kicking ideas around with a mate of his, Heath Biggs, and floated the idea of a tube chassis with forced articulation.
The car was demoed, unfinished, at the Easter Jeep safari in 1997, and went straight onto the cover of Petersens.
This is as it appeared in Petersens,
and this is how it ran at fourwheeler's top truck challenge in 1998, winning by a massive margin.
This car used one link suspension (an a-frame welded to the diff and a panhard rod) in the front, and a one link welded to the diff in the rear. There is NO side to side springing in the rear at all.
By a combination of rocker arms and torsion bars, if the RHF wheel rises, the LHR wheel must also rise. The ratio is 30% front, 60% rear. for articulation.
Springing in the rear is taken car of by opposed airbags that only apply to vertical travel not articulation. They are mounted to the articulated subframe.
After the scorpion came out, people tried all sorts of ideas including diff centres and extra propshafts, hydraulics, air actuators etc. even the current range rover interlinks its airpsrings when in low range to "force" articulation.
It is not a perfect system at all. It works amazingly well when the suspension is working in its range of motion, equalising wheel loadings and allowing an extremely "free" suspension without spooky behaviour on side angles.
It also can prevent the problem of a wheel down in a hole stopping the car becuase that wheel will be equally, rather than preferentially loaded.
anyway, It isn't perfect. In severe compound angle situations, it can work againt you because when the vast majority of the car weight is on the rear, the car can "flop" over into full articulation, and the front will follow, actually throwing the car off the hill.
If anything like this system was applied to a full bodied car, the effect of the weight over the rear wheels will amplify this problem and make it very spooky.
PS Soni Honneger did something important ot my impressionable mind though and has been responsible for a lot of my interest in the technical side of 4WDing.
I would still own a scorpion in a heartbeat. They are a usable tube car and have a lovely purity of design that is miles ahead of most tube cars built. It is now a production chassis - http://www.scorpion4x4.com/ although it has never been braodly commercially successful as it is not really intended to run massive tyres or look very pimpin' It was originally built with D44's and 35" tyres. Soni still drives one, powered by a cummins 4BT diesel, and will full weather protection, roof rack, doors, wipers, the lot.
did that make me sound like a trainspotter?
Mechanically forced articulation was first devised in a recreational off road vehicle by Soni Honneger (sp?) in about 1997. Soni, based in Arkansas, is a Swiss national who migrated to the us and set up a company called recovery engineering, looking after projects like pulling derailed rail cars out of swamps etc. However, he also is an avid 4WDer and a fan of the military aesthetic, he built a couple of cool military projects - The "War Wagon" a dodge ram pickup on 40" tyres, and the "slickrock spider" a coil converted flatfender.
Around 1996 or so, he was kicking ideas around with a mate of his, Heath Biggs, and floated the idea of a tube chassis with forced articulation.
The car was demoed, unfinished, at the Easter Jeep safari in 1997, and went straight onto the cover of Petersens.
This is as it appeared in Petersens,
and this is how it ran at fourwheeler's top truck challenge in 1998, winning by a massive margin.
This car used one link suspension (an a-frame welded to the diff and a panhard rod) in the front, and a one link welded to the diff in the rear. There is NO side to side springing in the rear at all.
By a combination of rocker arms and torsion bars, if the RHF wheel rises, the LHR wheel must also rise. The ratio is 30% front, 60% rear. for articulation.
Springing in the rear is taken car of by opposed airbags that only apply to vertical travel not articulation. They are mounted to the articulated subframe.
After the scorpion came out, people tried all sorts of ideas including diff centres and extra propshafts, hydraulics, air actuators etc. even the current range rover interlinks its airpsrings when in low range to "force" articulation.
It is not a perfect system at all. It works amazingly well when the suspension is working in its range of motion, equalising wheel loadings and allowing an extremely "free" suspension without spooky behaviour on side angles.
It also can prevent the problem of a wheel down in a hole stopping the car becuase that wheel will be equally, rather than preferentially loaded.
anyway, It isn't perfect. In severe compound angle situations, it can work againt you because when the vast majority of the car weight is on the rear, the car can "flop" over into full articulation, and the front will follow, actually throwing the car off the hill.
If anything like this system was applied to a full bodied car, the effect of the weight over the rear wheels will amplify this problem and make it very spooky.
PS Soni Honneger did something important ot my impressionable mind though and has been responsible for a lot of my interest in the technical side of 4WDing.
I would still own a scorpion in a heartbeat. They are a usable tube car and have a lovely purity of design that is miles ahead of most tube cars built. It is now a production chassis - http://www.scorpion4x4.com/ although it has never been braodly commercially successful as it is not really intended to run massive tyres or look very pimpin' It was originally built with D44's and 35" tyres. Soni still drives one, powered by a cummins 4BT diesel, and will full weather protection, roof rack, doors, wipers, the lot.
did that make me sound like a trainspotter?
[quote="greg"] some say he is a man without happy dreams, or that he sees silver linings on clouds and wonders why they are not platinum... all we know, is he's called the stevie.[/quote]
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