Balancing ring
Martin, that is what led me to the almost certain conclusion that the balancing ring at the front of the tub failed. Maybe a foreign object burst it, or a ballbearing somehow got stuck in a deformed portion and then suddelny loosed up causing a rapid weight shift.
Further, the rear berings shattering would have to pierece a metal sheet or a plastic plate in either direction to even just escape the machine.
You should be familiar with some fluid or even movable weight based balancing system from your Neptunes.
There is a ring around the front and/or back of the drum on the outside, probably fairly sturdily bolted or clipped in.
That is basicly a hollow profile, filled weither a heavy fluid and/or ball bearings of various weights.
I think on some Neptunes the paddles were filled, but that was just weight and couldn't shift much during spinning.
The idea is that after distribution in preperation for the spin, the load in the drum itself behaves like a solid with a given distribution. No matter how high you crank the spin speed, the laundry will stay in the same place relative to the drum.
The fluid and round ball bearings however can still move inside the balance rings. They experience the same forces pressing them against the the walls of the balance rings as the laundry does towards the tub, but they can behave like a fluid and flow even under that pressure.
During the intial distribution, the movement an OOB load induces in the drum causes a force pattern that shifts the contents inside the balancing ring towards the opposite site of where the heavier parts of the load are.
That creats counterforces to the forces the load excerts.
During the extraction process, these play another role.
No load is even 100% even and simmilar, so different parts of the load extract differently. This can cause slight shiftes in weight in the load. These shifts are usually not high enough to even effect the possibility of reaching the maximum spin speed, but they might cause some more vibration at high spin speed swhich the consumer might find annoying.
Otherwise, the only way to completly compensate for these would be to distribute after each spin increment.
The balancingrings however can adapt on the fly, no matter how high the spin speed is. The distribution of the materials in them dynamicly shifts as the weight of the laundry shifts.
This also explains some of the weired behavious of some machines with such balancing rings.
If you let the machine run an empty spin, the drum might seem out of balance even though the drum is empty. This is due the balls in the rings now distributing randonly at first. As there is no force that would guide them into a correct position, they randomly distribute and thus create a possible balancing issue themselfes.
Also, some uses describe that when the machine prepares to spin or starts to ramp up, sometimes, the drum seems to shake violently at first but then quickly and suddely calms down a lot even though the washer just kept ramping up. That is the different weights in these balancing rings distributing and findig the right places to counter the bad load distribution.
One manufacturer here in the EU went to the extend to add a water tank to each baffle which is then filled with exactly the right amount of water during distribution to balance the load near perfection basicly every time.
As there is not one fixed weight used as counter-balancing, it much more accurate and flexible then balancing rings.
