</font><font color="blue" class="small">( Sorry Uhmgawa,
But you lost me a bit too, I have read and re-read your explanation...
And understand your "reverse stress loading" statement. Although when working a setup like Flusher's example the bucket is useful to provide vertical alignment/support of the sample lift.)</font>
That scenario isn't as much of a concern as the load is
fixed and not impact-applied. Ie: you either lift the load
or the relief valve vents. In this case the loader/hydraulic
system is able to protect itself per design.
As a contrived example to the contrary for the same scenario,
if you were to strike the bottom of the wall on the foundation
while the tractor was traveling horizontally you could
impact load the hydraulic system beyond its design limit.
</font><font color="blue" class="small">( But, why would 4WD CG be different than 2WD?)</font>
Operating in 4WD the front axle can generate sufficient
torque to lift the rear end of the tractor. This is also the
reason chains should be routed around the back of a loader
bucket and exit under the bucket, with the bucket positioned
as low as possible. Attaching a chain directly to the top of a
bucket creates greater mechanical advantage to lift the rear
end as well as the ability to do so by increasing traction of the
front tires. Chains routed via the bucket bottom are also
marginally safer in the case of breakage.