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Old 31st January 2011, 21:51   #46
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Default Re: Mahindra Thar : Test Drive & Review

Samurai, by loaded I meant in payload / GVW (just to lay down a boundary condition). The graph shown by you seems interesting, I am interested to know why this is happening / why this behavior, where did you get this graph out from?

AFAIK, when talking about RTI we are dealing with lateral weight transfers where spring rates and roll stiffness do not play any role then how come the CG begins to shift in a non linear pattern?

Spike
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Old 1st February 2011, 01:06   #47
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Default Re: Mahindra Thar : Test Drive & Review

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Originally Posted by SPIKE ARRESTOR View Post
The graph shown by you seems interesting, I am interested to know why this is happening / why this behavior, where did you get this graph out from?

AFAIK, when talking about RTI we are dealing with lateral weight transfers where spring rates and roll stiffness do not play any role then how come the CG begins to shift in a non linear pattern?
Well, I put Jeeping common sense and Microsoft paint together, and the graph came out.

I drew the graph based on the observation. CG is not merely an engineer's concept. Even dancers and martial artists use the understanding of CG to perform intricate moves without falling down.
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Old 1st February 2011, 07:44   #48
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Default Re: Articulating on Articulation

^^ Well that is why I thought the graph is wrong and asked that question. Observations unless approved by scientific backing are of little use.

Spike

PS- I knew that graph was framed.
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Old 1st February 2011, 07:55   #49
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Default Re: Articulating on Articulation

The burden of proof is on you Spikey, not me. BTW, I really want to know why science is opposite of the observation here. I am basically talking about horizontal shift in CG, not vertical shift.

Last edited by Samurai : 1st February 2011 at 08:35.
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Old 1st February 2011, 08:44   #50
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Default Re: Articulating on Articulation

Hmm, let me see if I can find out something. I have done CG tests with a unladen and laden vehicle, it is generally seen that the shift in CG along Y axis is very little ( single digits in mm), whereas it is more in the case of X and Z axis.

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Old 1st February 2011, 09:31   #51
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Default Re: Articulating on Articulation

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Observations unless approved by scientific backing are of little use.
That's a curious statement to hear from an engineer. How can something become useless unless it is scientifically proved? The idea of weight (a function of gravity) was used for thousands of years before Newton discovered/defined gravity. Roman aqueduct was powered entirely by gravity, and that was 2000+ years ago.

Last edited by Samurai : 1st February 2011 at 09:41.
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Old 1st February 2011, 09:59   #52
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Default Re: Articulating on Articulation

Hmm, you are right, what I meant was "there must be reasoning for such observations", my sentence was cockeyed a bit.

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Old 1st February 2011, 10:07   #53
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Default Re: Articulating on Articulation

One small Q

what will happen if the Thar's ( yes again it is ) anti roll/ sway bar or the stabiliser bar be disconnected ?

Will the articulation improve ? at the cost of road behavior ?

or can a setup be developed to connect it for road & disconnect for off road by putting a pin or removing it .

Sudarshan

Last edited by Sudarshan : 1st February 2011 at 10:23.
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Old 1st February 2011, 10:30   #54
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Default Re: Mahindra Thar : Test Drive & Review

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Originally Posted by SPIKE ARRESTOR View Post
Arka, I can understand your point of RTI. How will longitudinal and lateral weight transfer effect this? You are talking about lateral weight transfers right? The opposite was being told here. Can you tell me how / how much CG shifts when?

a) Loaded and lifted diagonally
b) Loaded and lifted from one end (say front or rear)

Spike
Quote:
Originally Posted by SPIKE ARRESTOR View Post
Samurai, by loaded I meant in payload / GVW (just to lay down a boundary condition). The graph shown by you seems interesting, I am interested to know why this is happening / why this behavior, where did you get this graph out from?

AFAIK, when talking about RTI we are dealing with lateral weight transfers where spring rates and roll stiffness do not play any role then how come the CG begins to shift in a non linear pattern?

Spike
Hi Spike,

I think Lateral Load Transfer is the shifting of the CG, across the axle beam, or the Chassis Cross Members. This is called Rolling in off-road parlance.

But when the CG shifts along the Chassis Rails or the Wheel Base it is called Flipping.

I don't have any exact values, but observations.

CG will shift in a non linear pattern beacuse the suspension travel between front and rear wheels are not IDENTICAL.

The Rear Axle has more Travel, and more obviously in the M&M Thar.

Regards,

Arka

PS - If non-scientific observations are accumulated, using research methodology, then you end up having a huge sample size, which increase the accuracy of the hypothesis, Isn't that why Yoga and Ayurveda have survived for centuries
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Old 1st February 2011, 10:39   #55
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Default Re: Articulating on Articulation

Quote:
Originally Posted by SPIKE ARRESTOR View Post
Hmm, let me see if I can find out something. I have done CG tests with a unladen and laden vehicle, it is generally seen that the shift in CG along Y axis is very little ( single digits in mm), whereas it is more in the case of X and Z axis.

Spike
Spike, can you not simulate this on the computer to find the shift in CG? That will give us concrete information. You should be able to do it with the Xylo or the Scorpio model. Let me see what I can find out too.
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Old 1st February 2011, 12:06   #56
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Default Re: Articulating on Articulation

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Originally Posted by ex670c View Post

CG will shift in a non linear pattern beacuse the suspension travel between front and rear wheels are not IDENTICAL.

PS - If non-scientific observations are accumulated, using research methodology, then you end up having a huge sample size, which increase the accuracy of the hypothesis, Isn't that why Yoga and Ayurveda have survived for centuries
Arka, I don't know about Yoga or Ayurveda but Science and God never go hand in hand. This is a very delicate and serious topic so I rest my case here.

I am not an expert when it comes to offroading parlance (I am still learning), but with whatever little I know, your reasoning fails to convince me i.e. why should CG shift non linearly?

Yes, for IFS vehicles front and rear travel is different, what about solid axles then? Original CJ3Bs had same travel and rates for front and rear.

Quote:
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Spike, can you not simulate this on the computer to find the shift in CG? That will give us concrete information. You should be able to do it with the Xylo or the Scorpio model. Let me see what I can find out too.
No need to simulate man, I've actually tested all this physically with my own hands. Although not on a Xylo or Scorpio.

Spike
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Old 1st February 2011, 12:41   #57
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Default Re: Articulating on Articulation

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Originally Posted by SPIKE ARRESTOR View Post
Arka, I don't know about Yoga or Ayurveda but Science and God never go hand in hand. This is a very delicate and serious topic so I rest my case here.

I am not an expert when it comes to offroading parlance (I am still learning), but with whatever little I know, your reasoning fails to convince me i.e. why should CG shift non linearly?

Yes, for IFS vehicles front and rear travel is different, what about solid axles then? Original CJ3Bs had same travel and rates for front and rear.
Hi Spike,

What is your explanation for the 2 JEEPs rolling over to their sides (Aavalakonda 2011; Driver Error aside), isn't that Lateral Shift of the CG?

In the CJ3B are the (Front and Rear)
i) Leaf Springs the Same Length?
ii) same Shock Absorber Length?

Regards,

Arka
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Old 1st February 2011, 12:52   #58
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Default Re: Articulating on Articulation

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Hi Spike,

What is your explanation for the 2 JEEPs rolling over to their sides (Aavalakonda 2011; Driver Error aside), isn't that Lateral Shift of the CG?

Arka
Yes Arka, you are absolutely correct, both these roll overs were resultant of the shift in CG, but both were SOLID AXLE Jeeps, quite contrary to what is being discussed here!

Spike
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Old 1st February 2011, 13:01   #59
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Default Re: Articulating on Articulation

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Yes Arka, you are absolutely correct, both these roll overs were resultant of the shift in CG, but both were SOLID AXLE Jeeps, quite contrary to what is being discussed here!

Spike
Hi Spike,

Are you suggesting that in an IFS there will be not Lateral Shift of CG, since the Front Axle is bolted to the Chassis?

Regards,

Arka
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Old 1st February 2011, 13:02   #60
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Default Re: Articulating on Articulation

Spike, can you kindly prove my graph wrong. I am still waiting.

Arka, what is your opinion of my graph in post#45?
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