Spring pressure????

typical stiffnesses: front 133lb/inch rear 150lb/inch

but I have to ask whether the terminology of your question suggests you may not have enough engineering knowledge to do something that could affect ride and handling so drastically. Unless you're never going to take it on the road, your insurers may also have a view on such mods.

Quite right, I don't have the faintest idea what I am doing for the road..... but I think I have a plan for an off road experiment, but it may not work !!!!!!!!

Now that I have the spring pressures, I can simulate that pressure with the correct diameter air bag and correct air pressure.. and I can see what happens, obviously there is no progressiveness to the system depending on how the air bags are set up and linked, but I suppose it will be trial and error.

Thanks Rich

Hang on, that suggests it's not the spring stiffnesses that you wanted to know, but the load on each corner, which is nothing to do with the existing springs.

(weight of vehicle - weight of two complete axles - weight of 4 wheels & tyres) /4

3900lb - 400lb (guess) - 150 lb (another guess) = 3350lb, or say 850lb load on each spring (Reality check - this is about 6" deflection - sounds about right for a spring that's around 16" unloaded, and 4" fully coilbound)

You really sure about this?

I've seen air-suspension systems that have been removed from range rovers on ebay, maybe a good place for you to start is to get one of these and work from there.

Regards. Mark.(AKA, Mr.Nice.)

Hi all, ok sorry for the bad way I put the question, what I think I need to know is what sort of force is exerted on each spring when the vehicle is under normal conditions say stationary and not loaded ?????

Also with reference to the last post I don't want to use air bags as I want more suspension travel than they can give !!!!!!!! also it will have 3 rear axles to cope with a hi-cap body and smallish hiab, and give good off road capability with all axles driven..

Rich

C'mon, you're extracting it now, surely?

That's exactly what I answered in my last posting (23/11):

(weight of vehicle - weight of two complete axles - weight of 4 wheels & tyres) /4

3900lb - 400lb (guess) - 150 lb (another guess) = 3350lb, or say 850lb load on each spring

Or do you need it in these new-fangled metric units? Or in ton-furlongs/square fortnight?

And three rear axles? Why stop at three? Ah - just spotted the clue in your email address "r3engineering@..." The engineering bit still has me puzzled.

Ummm, what does the axles, wheels and tyres have to do with it, all this is un-sprung weight, so is irrelevent surley, only the body and chassis act on the springs, so this is the only weight which is important ???

Old units are just fine for me....

Why three ? Why not !!! I have only seen Land Rovers and Range Rovers with two so three would be quite different !!!! to fit a Hiab and high cap body it is going to be long so 3 would look good, and I like a challenge.. The engineering bit is what my friends have nic named me as I generaly over engineer every thing, better safe than sorry..

Rich

Ah, just read your post properly, these marks ( - ) are to mean minus aren't they !!! so your calculation is correct except the guessing on the weights which I can understand could be a bit out..

Thanks

Rich

On or around Thu, 25 Nov 2004 17:35:58 GMT, "Rich" enlightened us thusly:

there are 6-wheel Land Rovers about, and Range Rovers.

A fairly well-established convention, I think, in the context of a calculation.

Well yes, I'd been to enough trouble to confirm the spring rates and initial lengths, which turned out not to be needed, without dismantling the Rangey to weigh an axle.

Indeed, but this chappy is "designing" a 4-axle (I assume 8 wheel) version, but, sadly, with only one front axle and three rear, all of them driven, which Carmichael, afaik, never managed on their 3-axle fire tenders.

Yes have driven them in the electricity industry as Simon towers.

Yes, dead right, 4 axles, 3 at the rear, one steering at the front, all driven !!!! Dont understand you say Carmichael never managed it with two ??

Why do you say "sadly, with only one front axle and three rear" ??

I cant see a problem driving three rear axles, just throw in various props, a transfer box, stir it all about and away you go, only problem could be the overall length and the weight of complete vehicle and turning circle..

But if any one knows better please give some input !!!

Rich

James Taylor's book "Original Range Rover" shows a few six-wheelers, but all with one driven rear axle and one unpowered. They may, of course, have made 6x6s as well.

I rather liked the notion of twin, steered, powered front axles, that's all.

I can't quite picture where these extra prop shafts would fit, or indeed where the two extra axle-axle diffs would go, but hey, I'm no designer.

That's all right then

Yeh, c'mon you customisers. What's the opposite of "bobtail"?

The problem I could see is that of scrubbing all the tyres.

With an 8x8x2 setup you have one steering axle and a further three static axles - when turning your pivot point is going to be somewhere between the #2 and #3 axles with the #1 and #4 axles being further out - the result is that the wheels on the #4 axle will end up getting dragged sideways when you're turning and you will scrub the tyres quite badly. You also stand a fairly good chance of the #1 (steering) axle ending up in what is effectively terminal understeed because it just doesn't have enough traction to drag the other three round. All of this is assuming approx.

100" wheelbase between #1 and #2 axles and then around 40" wheelbase between #2,#3 and #4

If I was doing this I'd look at building an 8x8x4 configuration with either the #1 and #2 axles steering with 40" wheelbase between them and then 100" between the #2 and #3 which would give you a Land Rover that thinks it's a Scammell Explorer, or another (probably better) choice would be to have the axles spaced approximately

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and have the #1 and #4 axles steering around a turning point dead centre on the car - no tyre scrubbing and turning characteristics similar to a dumper truck.

Of course, the other, stranger, approach would be to build an 8x8 with no "steering" per-se and go with fiddle brakes on all axles. At that point you have a Land Rover Argocat.

Something to consider with what you are trying to build is that it is effectively a half-track without the actual track.

P.

In increasing order of size:

Stretch SuperStretch? Disco 3 Scammell USS Nimitz Hummer

He's trying to "Hummerify" a Rangie.

P.

On or around Fri, 26 Nov 2004 18:11:28 GMT, "Rich" enlightened us thusly:

You want 2 transfer boxes, back to back.

however... I'd make at least the rear-most axle steer, meself, or mayhap the frontmost one. Otherwise you'll have silly amounts of tyre scrub.

someone actually makes an 8-legger, using 2 T-boxes. I had a link to it once, I spect I've lost it now. There was one for sale in LRO a year or so back.

This was the old Esarco, renamed MWG then .....

"Two full-time four wheel drive Land Rover transfer cases were used, mounted back to back with the first driving the second through their power take-offs by a dog-clutch and a short drive shaft. The first transfer case drove axles one and three and the second transfer case drove axles two and four. The axle differentials being offset, the prop-shafts could pass neatly over the intervening axles on their way to the appropriate differentials. All in all there were six differentials - four in the axles and two in the transfer cases."

Various bits of history here:

One of the UK 4x4 magazines had an article on the original many years ago.

On or around Fri, 26 Nov 2004 19:01:55 +0000, "Paul S. Brown" enlightened us thusly:

the 8x8 one I've seen pictures of has front and rear axles steering.

aha:

I'm sure I had some info sheets about it. I still have a copy of the ad in LRO on the machine here.

can't find 'em ATM though.

I've just found an illustration of the drivetrain of the MWG version (Perkins engine). Can I send it to someone who's prepared to host it?

On or around Fri, 26 Nov 2004 21:12:59 +0000, Dougal enlightened us thusly:

Aye, that's the kiddie.

dunno where I got specsheets from. I did, previously, with diagrams and everything. They were also using LR suspension, with ISTR 4 lots of front suspension with turrets. The rearmost axle is a front one mounted facing backwards, I think, while axle 2 is a rear one mounted backwards. Whether you really get enough clearance to run propshafts over axles, I don't know.

There's also a version of the design built in the US, but using US components.