I was idly wondering this today.
Since they are connected to the roof, does that mean that the CoG of the trailer will be higher up (when/if the internals come under a load) say you had to swerve, or just took a corner like a bellend.
Not at all. All that happens when under load is the straps/ roof bar take the strain of said bellend tyre shredding cornering, the c.o.g stays the same…
slowlane:
I was idly wondering this today.Since they are connected to the roof, does that mean that the CoG of the trailer will be higher up (when/if the internals come under a load) say you had to swerve, or just took a corner like a bellend.
Good question! And I suspect it might move the centre of gravity! Any centrifugal force acting on the internal straps will be transmitted through the two points where it is connected to the trailer so I think it will have some effect.
Given that the straps would have a downward and outward force on them I would have thought the centre of gravity would be lowered, but not too significantly.
On the other hand if a load on the top deck of a double decker slipped and was being held be the internal straps I imagine it could raise the COG.
No, the centre of gravity stays the same, because the shape and location of the mass do not change. There will be a force of leverage acting on the roof, but because of the acute angle between the roof and the strap, that force won’t be massive.
Centrifugal force will move the centre of gravity although the mass itself might not have moved an inch. Centre of gravity should be thought as a force acting on the mass. Introduce an additional force such as centrifugal force and all those forces move around and that will include the centre of gravity. Whether it raises or lowers that will depend on the exact position of the straps in relation to the load. I believe!
TiredAndEmotional:
slowlane:
I was idly wondering this today.Since they are connected to the roof, does that mean that the CoG of the trailer will be higher up (when/if the internals come under a load) say you had to swerve, or just took a corner like a bellend.
Good question! And I suspect it might move the centre of gravity! Any centrifugal force acting on the internal straps will be transmitted through the two points where it is connected to the trailer so I think it will have some effect.
No it won’t. The centre of gravity is the centre of the mass. Has anything moved? Only the roof which may have got lower so it would lower it fractionally by maybe millimeters at the most.
it’s a travesty that such wonderful and powerful minds are used to deliver 26 pallets of cat litter to Aldi 
Going back to the time when Tautliners had only recently come on the scene I found it very noticeable how much more a curtainside rigid swayed than did a flat platform when carrying a similar load. Obviously there was a difference in unladen weight because of the additional bodywork. Of course those were the days when internal straps were used almost religiously, rather than seen as a nuisance or too much trouble as they are now. As has been said a force is acting on the roof pole when the vehicle sways or corners. Very little feeling of what is going on in the trailer other than a sense of pitching, is transmitted to the driver of an artic unless we are considering a liquid load.
eagerbeaver:
it’s a travesty that such wonderful and powerful minds are used to deliver 26 pallets of cat litter to Aldi
Conor:
TiredAndEmotional:
slowlane:
I was idly wondering this today.Since they are connected to the roof, does that mean that the CoG of the trailer will be higher up (when/if the internals come under a load) say you had to swerve, or just took a corner like a bellend.
Good question! And I suspect it might move the centre of gravity! Any centrifugal force acting on the internal straps will be transmitted through the two points where it is connected to the trailer so I think it will have some effect.
No it won’t. The centre of gravity is the centre of the mass. Has anything moved? Only the roof which may have got lower so it would lower it fractionally by maybe millimeters at the most.
No it isn’t. We’re not dealing with a uniform mass when talking about a trailer.
TiredAndEmotional:
Conor:
TiredAndEmotional:
slowlane:
I was idly wondering this today.Since they are connected to the roof, does that mean that the CoG of the trailer will be higher up (when/if the internals come under a load) say you had to swerve, or just took a corner like a bellend.
Good question! And I suspect it might move the centre of gravity! Any centrifugal force acting on the internal straps will be transmitted through the two points where it is connected to the trailer so I think it will have some effect.
No it won’t. The centre of gravity is the centre of the mass. Has anything moved? Only the roof which may have got lower so it would lower it fractionally by maybe millimeters at the most.
No it isn’t. We’re not dealing with a uniform mass when talking about a trailer.
Oh yes it is ! 
The whole point when using the concept of a Centre of Gravity or Centre of Mass is that the mass (including of a non uniform body) can be considered to act at one point.
Remember, it was YOU that first used the term CoG! You cant use that term in your original post and then argue it isnt valid can you?
Andrew, Conor and the Donkey seem correct to me, whether or not internal straps are used, the C of G remains the same.
To try and address the thought behind the original question: are you asking whether using internal straps, attached to the roof, will affect the stability of a trailer?
Franglais:
Oh yes it is !The whole point when using the concept of a Centre of Gravity or Centre of Mass is that the mass (including of a non uniform body) can be considered to act at one point.
Remember, it was YOU that first used the term CoG! You cant use that term in your original post and then argue it isnt valid can you?Andrew, Conor and the Donkey seem correct to me, whether or not internal straps are used, the C of G remains the same.
To try and address the thought behind the original question: are you asking whether using internal straps, attached to the roof, will affect the stability of a trailer?
No the first person was slowlane actually. You’re not quite grasping what Conor said that’s incorrect. He said the C of G is the centre of the mass. That is only correct for a uniform mass of a uniform material e.g. a cube of concrete. A trailer with a load on which is what we’re talking about here can in no way be considered to be uniform. A trailer on its own is not uniform. The load might be but as soon as you put it on a trailer the uniformity is lost. C of G of a stationary load might remain the same but a moving load which is the scenario here will have a moving C of G according to the forces applied on it, especially side/centrifugal forces. I’m not asking anything! I’m giving my opinion on the question raised by slowlane. And to answer his question accurately would require relevant weights and measurements pertaining to the situation and the use of a calculator! I suggest you read the thread carefully! 
TiredAndEmotional:
Franglais:
Oh yes it is !The whole point when using the concept of a Centre of Gravity or Centre of Mass is that the mass (including of a non uniform body) can be considered to act at one point.
Remember, it was YOU that first used the term CoG! You cant use that term in your original post and then argue it isnt valid can you?Andrew, Conor and the Donkey seem correct to me, whether or not internal straps are used, the C of G remains the same.
To try and address the thought behind the original question: are you asking whether using internal straps, attached to the roof, will affect the stability of a trailer?
No the first person was slowlane actually. You’re not quite grasping what Conor said that’s incorrect. He said the C of G is the centre of the mass. That is only correct for a uniform mass of a uniform material e.g. a cube of concrete. A trailer with a load on which is what we’re talking about here can in no way be considered to be uniform. A trailer on its own is not uniform. The load might be but as soon as you put it on a trailer the uniformity is lost. C of G of a stationary load might remain the same but a moving load which is the scenario here will have a moving C of G according to the forces applied on it, especially side/centrifugal forces. I’m not asking anything! I’m giving my opinion on the question raised by slowlane. And to answer his question accurately would require relevant weights and measurements pertaining to the situation and the use of a calculator! I suggest you read the thread carefully!
From Wiki:
“In the study of the dynamics of aircraft, vehicles and vessels, forces and moments need to be resolved relative to the mass center. That is true independent of whether gravity itself is a consideration. Referring to the mass-center as the center-of-gravity is something of a colloquialism, but it is in common usage and when gravity gradient effects are negligible, center-of-gravity and mass-center are the same and are used interchangeably.”
When referring to the center of mass, I wasn`t referring to the physical center of the body (the trailer and load) but to the Center Of Mass of the trailer and load.
If you are suggesting that putting a load into an empty trailer will affect the C of G, then of course that is correct. No one (I think) is arguing with that.
The C of G of an empty trailer, will be different from that of a loaded trailer. The C of G of a loaded trailer will remain the same whether or not internal straps are used.
The Centre of Mass is just that! No one said it is in the center of a body. (in this case a trailer and load).
No calculator, or specific weights, masses or other dimensions are necessary to address the general principles behind the original question really are they? To work exactly where the C of G is with a specific load, on a specific trailer, those are necessary, but not needed in this discussion.
Well, maybe Ive got it totally wrong, wont be the first time, but I suspect that you may be reading meanings into words that aren`t really there?
No offence meant at any point, by the way.
P.S. Oh, Yes it is ! (mostly)
eagerbeaver:
it’s a travesty that such wonderful and powerful minds are used to deliver 26 pallets of cat litter to Aldi
I am a theoretical physicist specialising in Quantum Computational Algorithms, but I drive lorries to keep me grounded.
the nodding donkey:
eagerbeaver:
it’s a travesty that such wonderful and powerful minds are used to deliver 26 pallets of cat litter to AldiI am a theoretical physicist specialising in Quantum Computational Algorithms, but I drive lorries to keep me grounded.
I`m a stamp collector…
slowlane:
I was idly wondering this today.Since they are connected to the roof, does that mean that the CoG of the trailer will be higher up (when/if the internals come under a load) say you had to swerve, or just took a corner like a bellend.
Yes it will, but only of your load applies a sideways force on them, but even then, not enough to make a difference.
You’ll only have a problem with CoG if it falls outside the confines of your vehicle. And you’d have to be pretty stupid/unlucky for that to happen.
Captain Caveman 76:
slowlane:
I was idly wondering this today.Since they are connected to the roof, does that mean that the CoG of the trailer will be higher up (when/if the internals come under a load) say you had to swerve, or just took a corner like a bellend.
Yes it will, but only of your load applies a sideways force on them, but even then, not enough to make a difference.
You’ll only have a problem with CoG if it falls outside the confines of your vehicle. And you’d have to be pretty stupid/unlucky for that to happen.
Oh, no it won`t…
But as to your second point, wont the C of G always be within a normal real-world vehicle? The problems happen when the line from the C of G, to the earth, is outside of the footprint of the vehicle surely? i.e. you corner too rapidly, or are on a side slope, such that the C of G is past the outside edge of the vehicle, thats when the vehicle topples over.
Franglais:
Captain Caveman 76:
slowlane:
I was idly wondering this today.Since they are connected to the roof, does that mean that the CoG of the trailer will be higher up (when/if the internals come under a load) say you had to swerve, or just took a corner like a bellend.
Yes it will, but only of your load applies a sideways force on them, but even then, not enough to make a difference.
You’ll only have a problem with CoG if it falls outside the confines of your vehicle. And you’d have to be pretty stupid/unlucky for that to happen.
Oh, no it won`t…
But as to your second point, won
t the C of G always be within a normal real-world vehicle? The problems happen when the line from the C of G, to the earth, is outside of the footprint of the vehicle surely? i.e. you corner too rapidly, or are on a side slope, such that the C of G is past the outside edge of the vehicle, thats when the vehicle topples over.
This is from memory, it’s been quite a while since I’ve taught this stuff so there may be errors, but I’m confident enough that I’m right to put it down.
Second point first. The CoG is a mythical magical point that we Imagine the entire downward force to act from. You’re quite right, in normal operation it shouldn’t be outside the confines, or footprint (I like that term) of the vehicle. If it is, for reasons you said, you’re In trouble.
First point. I think theres a problem with the language being used. The mass will not move, therefore the centre of gravity will not move (youre right there). What WILL happen is that the forces acting on the trailer change. Instead of the load applying a complete downward force, some of it will be applied sideways. This will be transfered, via the restraints, to the structure of the trailer, causing it to lean. Just the same as a guest of wind blowing into the side. If the force is large enough, the trailer will move sufficiently for the CoG to fall outside of the vehicles footprint (I really like that term). Now you have trouble.
In essence, the centre of gravity doesn’t move in relation to the trailer, because the mass of the load doesn’t move in relation to the trailer. It does however move in relation to the road, because of the lean of the trailer.
Like I said, dug up from the dim and distant resources of my brain, but I’m confident that’s right. I just hope it makes sense!
And like all the best physics, I did it in the bath! 
Time to get out now, I’m getting even more wrinkly!!
Captain Caveman 76:
Franglais:
Captain Caveman 76:
slowlane:
I was idly wondering this today.Since they are connected to the roof, does that mean that the CoG of the trailer will be higher up (when/if the internals come under a load) say you had to swerve, or just took a corner like a bellend.
Yes it will, but only of your load applies a sideways force on them, but even then, not enough to make a difference.
You’ll only have a problem with CoG if it falls outside the confines of your vehicle. And you’d have to be pretty stupid/unlucky for that to happen.
Oh, no it won`t…
But as to your second point, won
t the C of G always be within a normal real-world vehicle? The problems happen when the line from the C of G, to the earth, is outside of the footprint of the vehicle surely? i.e. you corner too rapidly, or are on a side slope, such that the C of G is past the outside edge of the vehicle, thats when the vehicle topples over.This is from memory, it’s been quite a while since I’ve taught this stuff so there may be errors, but I’m confident enough that I’m right to put it down.
Second point first. The CoG is a mythical magical point that we Imagine the entire downward force to act from. You’re quite right, in normal operation it shouldn’t be outside the confines, or footprint (I like that term) of the vehicle. If it is, for reasons you said, you’re In trouble.
First point. I think theres a problem with the language being used. The mass will not move, therefore the centre of gravity will not move (youre right there). What WILL happen is that the forces acting on the trailer change. Instead of the load applying a complete downward force, some of it will be applied sideways. This will be transfered, via the restraints, to the structure of the trailer, causing it to lean. Just the same as a guest of wind blowing into the side. If the force is large enough, the trailer will move sufficiently for the CoG to fall outside of the vehicles footprint (I really like that term). Now you have trouble.
In essence, the centre of gravity doesn’t move in relation to the trailer, because the mass of the load doesn’t move in relation to the trailer. It does however move in relation to the road, because of the lean of the trailer.
Like I said, dug up from the dim and distant resources of my brain, but I’m confident that’s right. I just hope it makes sense!
And like all the best physics, I did it in the bath!
Time to get out now, I’m getting even more wrinkly!!
Id suggest that the forces remain the same: For any given situation, (lets take the example of going around a corner?), the force needed to get the load to change it`s velocity by any amount is a constant.
It can be applied to the load by friction, or straps fastened to the bed, or twist-locks or, as being discussed, internal straps. The forces acting on the load are independent of the way they are applied to the load. Assuming the load doesnt move it doesnt matter how it`s secured, as the C of G remains the same, so the forces acting on it also remain the same.
You can resolve the forces acting in very complicated ways, but you dont need to. So long as the system acts as a whole there is no need to do any hard stuff and break it into its component forces, only to have to re-integrate them.
Youve been too long in the bath, Cavey! Dont overthink it.