Ok, Ok, you're rushing me so this is off the cuff............... Your figures don't stack up. Neither does your metholgy. If we take the roof off your van and attach a ratchet strap around two buses and then onto your tank mounts, and lift your van in the air to lift the buses up the the bolts will rip out the van floor. Don't argue Physics with me either as most vans are good for a 6, 800, 100 kilo payload or what ever and NOT 18,000 KG.
I see where your misunderstanding comes from; you've missed an important point. As I said in my explanation earlier in the thread, the situation in an accident is the same as if you turn the van
on its nose and rest the 18,000 kg against the bulkhead (or tank, or whatever's holding the water back). You'll note that all the forces on the tank mounts are shear forces (at right angles to the bolts). You're not trying to rip the bolts out of the floor vertically as in your example. To see the difference, stick a normal pin in a bit of cardboard. Pull it all the way through and it's pretty easy. Try to rip it sideways through the cardboard. Difficult to the point of impossibility.
You make no distinction in your assesment of how things will pan out in as much as, if 600KG is affixed firmly to a bulkead and a sudden stop occurs what its impact will be Vs 600KG in the middle of the load bed coming unsecured and flying through a bulkhead ? As i mentioned earlier in this thread, the fact alone of loading against a bulkhead, to stop any forward momentum, as opposed to loading away from a bulkhead where a load or fixture can gather momentum will lead to very differnent forces. You based your bus assumption on which one ?
There is a distinction but it's irrelevant. If the van is decelerating at 30g then the force acting on whatever's holding the load back
has to be thirty times its weight. I'm happy to work it all out in Newtons but all of the units cancel out so you may as well take the short cut and say deceleration in g multiplied by mass. Saves a great deal of maths.
The bus assumption is based on
both scenarios. If the van is decelerating at 30g then the force acting on whatever is holding the 600kg load back will be 18,000kg. It doesn't matter if the tank's held with straps, blu-tack or whatever, the forces will be the same. Then, in your scenario, the tank starts moving and hits the bulkhead and yes, you're right, it probably passes through the bulkhead because the impulse (force over time of action) is huge as it hits the bulkhead. That would be relevant if at any point I'd been arguing that unrestrained (or insufficiently restrained) away from the bulkhead is as good as up against the bulkhead. Sadly, I've not been saying that, you're the one fixated with that comparison.
And while i've got ya, if we lift buses up with your van system do we go steady, or snatch 'em up real quick ?
I'm not lifting buses.
Anyway, you're not interested in anything factual as you've decided,
with no basis apart from your opinion, that up against a bulkhead is safe. The physics says that if the bulkhead can withstand an 18,000kg weight acting along the axis of the van then you're right.
Note (and I know you haven't) that at no point have I said that a bulkhead can't withstand 18,000 kg. I've taken a look at a couple of bulkheads since this thread started and while I suspect mine wouldn't (Hiace), a Vivaro's might, much more substantial. But the problem is that's guesswork.But my job here isn't to convince you. You're unconvincable (I'm already awaiting yours and your cronies' posts telling me how sad I am and how tragic that I actually understand physics).
No, my aim is to convince anyone reading this with an open mind that a crash-tested system is the way to go rather than believing the word of a bloke on the internet who tells them that up against a bulkhead is safe.
For the sake of a couple of thousand quid over ten years (£4 a week) you might just save your life.Vin
PS. If this post is too long for your attention span (boy, can I see
those posts coming), apologies. Sometimes difficult matters take a bit of space to explain.
PPS. Ref the upcoming torrent of abuse about how tragic I am, how little I really know, how odd that I can be a window cleaner
and understand physics at the same time, remember the final paragraph. This is potentially life and death and £4 a week might save your life.