Pros and cons of 8*8 against 6*6 wheeled vehicles
Pros and cons of 8*8 against 6*6 wheeled vehicles
(OP)
Dear Experts,
Does any know of a source to get info regarding the advantages/disadvantages regarding the ride/handling, weight transfer comparison of 6*6 against 8*8 etc?
Thanks
eddie
Does any know of a source to get info regarding the advantages/disadvantages regarding the ride/handling, weight transfer comparison of 6*6 against 8*8 etc?
Thanks
eddie





RE: Pros and cons of 8*8 against 6*6 wheeled vehicles
Front end alignment will be a lot more complex especially if you want to maintain Akerman on all 4 steering wheels, that is presuming 4 wheel steer which was not actually specified.
It might turn in better or under steer less if high speed handling s a consideration on a military type off road type vehicle if that is what it is which was also not specified.
Regards
Pat
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RE: Pros and cons of 8*8 against 6*6 wheeled vehicles
I am trying to get a picture of how a 6*6 compares to an 8*8 in terms of 'fatigue loading' of the suspension components.
Question: Would the 6*6 experience more fatigue loading if each wheel station on both 6*6 and 8*8 has the same sprung mass? I am asking this from a purely 'geometric configuration' point of view, if that makes any sense?
I am guessing that the 6*6 would be more susceptible to squatting and diving due to it CoG being in close proximity to the central axle. So from this I am visualising a rocking motion about this point as the vehicle accelerates and decelerates.
For the 8*8, I think the effects of squatting or diving would not be as significant. Although I am not sure.
I am surprise I couldn't find and articles relating the performances between 6*6 and 8*8 heavy vehicles in terms of ride and handling.
Any thoughts on this? thanks
RE: Pros and cons of 8*8 against 6*6 wheeled vehicles
Just to add...In addition to the above, the 6*6 has a higher CoG and shorter wheel base relative to 8*8
RE: Pros and cons of 8*8 against 6*6 wheeled vehicles
Maybe I am hard nosed, but it seems a bit absurd to try to compare unless you tie down the variables or just compare vehicle to vehicle and don't try to attribute all the differences to only one cause.
Regards
Pat
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RE: Pros and cons of 8*8 against 6*6 wheeled vehicles
Its sounds like an unreasonable question. I was just trying to get an idea of differences etc. Best option would probably compare the 2 vehicles using dynamic models.
RE: Pros and cons of 8*8 against 6*6 wheeled vehicles
I'm currently in the process of building a dynamic model of a 6*6 and an 8*8 both of which have different axle rating, springs, dampers, CoGs and wheel travel.
I would like to extract some useful information/characteristics to compare the wheel station of both for a given road profile like a speed bump, pothole.
I am interested in magnitude for forces on the suspension such as wishbone pivots and particularly king pin forces.
For example my first thought is to normalise the king pin force against its wheel force so that a direct comparison can be made between the vehicles. Other ideas include finding the energy absorbed by the wheel station by integrating the force displacement curve and comparing.
Does anyone have any other useful characteristics that could help to demonstrate differences between a 6*6 and 8*8?
thanks
RE: Pros and cons of 8*8 against 6*6 wheeled vehicles
Unless you have spent a million dollars or a couple of years your pothole forces will be indicative at best. A step(kerb impact) is easier to model.
Frankly I think the most likely outcome is that the leading axle gets most of the damage, and the other axles are along for the ride.
Cheers
Greg Locock
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RE: Pros and cons of 8*8 against 6*6 wheeled vehicles
I currently have modelled a step as one type of manoeuvre.
I was also considering a 200mm high 7m sine wave to see the effects of weight transfer of both vehicles as it traverses over the course.
What you think?
RE: Pros and cons of 8*8 against 6*6 wheeled vehicles
RE: Pros and cons of 8*8 against 6*6 wheeled vehicles
morris- yes once you hav a model throw it at lal sorts of raod surfaces, when you find a significant difference between the 6 and the 8 wheeler investigate that and see if it is reasonable.
We have something 15 different road profiles and 5 different sorts of potholes to play with.
Cheers
Greg Locock
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RE: Pros and cons of 8*8 against 6*6 wheeled vehicles
thanks guys.
Greg, are these road profiles and potholes based on some standard?
Thanks
RE: Pros and cons of 8*8 against 6*6 wheeled vehicles
Cheers
Greg Locock
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RE: Pros and cons of 8*8 against 6*6 wheeled vehicles
I am not quite sure where Asutralian is. is it anywhere near either Australia or Austria.
Regards
Pat
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RE: Pros and cons of 8*8 against 6*6 wheeled vehicles
Aside from the model, look at some video of 6x6 and 8x8 mil vehicles riding on courses if you can find any. The 8x8's that I have seen basically just glise all over the courses since they have a more stable platform. think of a centipede and how it's many legs make the load supported by each less. you can have softer ride sprigns on the 8x8 (assuming same mass like you mentioned) and if you have enough wheel travel then IMO the 8x8 is going to be a better choice for ride.
if i remember correctly, the front wheels of some multi (>2) axled vehicles sometimes are more highly damped due to them being the one that hit an obsticle first. this also depends on weight distribution and spring rates though.
what simulation program are you using?
RE: Pros and cons of 8*8 against 6*6 wheeled vehicles
RE: Pros and cons of 8*8 against 6*6 wheeled vehicles