center of gravity

**windsock** · 13th December 2009, 04:44 AM

Originally Posted by uninformed

gum trees are structuraly reliably UNRELIABLE regardless of branch/trunk dia.

hmmm, I am wondering if they differ between Aust and NZ. I have access to several old-man gums (exact type unknown) growing beside a stream and the only problem we have had is wind stripping small branches off them. They are not the 'widow-makers' I have seen in drier climates.

Agreed however on directly lifting a dead-weight on anything organic. I was thinking of wrapping a strap around and over the main trunk and over a branch on the opposite side from the truck and pulling up and towards the bank that the tree grows on. I figured if I park up in the right place I then can 'teeter' the truck at tipping point and have the bank to stop me going right over on my side.

Excavator would be by far the best option as far more controlable. A matter of persuading a somewhat conservative operator of the necessity

Certainly a task for when I have put stronger roll protection on and when no-one else is looking...

**Bush65** · 13th December 2009, 07:32 PM

The CoG can be calculated if you have suitable scales to measure the weight at each wheel when the vehicle is level, then when one end is elevated. The other required measurements are wheel base and height that the end was elevated.

Bathroom scales can measure the wheel loads by using a lever.

IMHO much less risk than tipping the vehicle over.

There is a good write up on one of the Jeep sites (jeepaholics from memory).

**Grover-98** · 13th December 2009, 08:05 PM

Originally Posted by Bush65

The CoG can be calculated if you have suitable scales to measure the weight at each wheel when the vehicle is level, then when one end is elevated. The other required measurements are wheel base and height that the end was elevated.

Bathroom scales can measure the wheel loads by using a lever.

IMHO much less risk than tipping the vehicle over.

There is a good write up on one of the Jeep sites (jeepaholics from memory).

Funny you should mention that, i was looking at that exact site last night! seemed far more practical.

**Grover-98** · 13th December 2009, 08:12 PM

Center of Gravity and Roll-Over Angle - Jeepaholics Anonymous have a read fellas.

**uninformed** · 13th December 2009, 08:15 PM

Center of Gravity and Roll-Over Angle - Jeepaholics Anonymous

yes its a good way of doing it, but in the past i have had difficulties getting a simple front and rear axle weight of my truck, let alone coming up with a way to raise the front of the vehicle 600mm off the ground, by supporting the tyres, with the rear on the scales........with all the legal stuff and time is money etc, i cant imagine to many scale places being up for it. If any one knows of one on the Gold Coast ill be happy to go do it, though im still trying to figure out how to get the front end up

Serg

**Grover-98** · 13th December 2009, 08:31 PM

Originally Posted by uninformed

Center of Gravity and Roll-Over Angle - Jeepaholics Anonymous

yes its a good way of doing it, but in the past i have had difficulties getting a simple front and rear axle weight of my truck, let alone coming up with a way to raise the front of the vehicle 600mm off the ground, by supporting the tyres, with the rear on the scales........with all the legal stuff and time is money etc, i cant imagine to many scale places being up for it. If any one knows of one on the Gold Coast ill be happy to go do it, though im still trying to figure out how to get the front end up

Serg

You could just use ordinary car ramps. And adjust the calculations to suit. You will find the COG regardless of if you raise it 600mm or 200mm.

James.

**uninformed** · 13th December 2009, 09:01 PM

Originally Posted by Grover-98

You could just use ordinary car ramps. And adjust the calculations to suit. You will find the COG regardless of if you raise it 600mm or 200mm.

James.

it clearly states that you must raise the vehicle at least 24 inches off the ground. Im going to go ahead and assume that the guy that put this together has done his research and knows why.

Serg

Zute · 14th December 2009, 01:41 AM

Finding the roll centre might be more practical.

**windsock** · 14th December 2009, 04:37 AM

Originally Posted by Grover-98

Center of Gravity and Roll-Over Angle - Jeepaholics Anonymous have a read fellas.

Now theres some good info right there for sure, thanks to Bush65 and Grover-98. I had access to the local landfill scales but may need to see who the new operator is before getting carried away with ramps etc. Discrete data and analysis followed by validation in the field...

Sounds like a nice little research project

**windsock** · 14th December 2009, 04:42 AM

Originally Posted by Zute

Finding the roll centre might be more practical.

If the web site info is calculated accurately, roll centre is a given as once COG is obtained, as aren't they one and the same? Assuming my understanding of rolling is correct

Roll angle may be another equally applicable and understandable phrase.

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