**My second photo in post #116 shows the extremely extended cylinders right down against the tip end of the loader frame.**

Yes, that picture definitely shows the issue. Assuming a distance of 24" from bucket tip to the pivot pin and 4" from the cylinder rod to the pivot pin gives a ratio of 6:1. So, assuming a point load on the bucket tip of 1000 lbs would produce six times that or 6000 lbs compressive load on the cylinder rod. The load on the cylinder would be reduced by half if the rod was 8" from the pivot pin. Might still bend the rod if too small of diameter.

The rod diameter is, as several mentioned, very important. A 1-1/4" diameter rod, for example, is 56% stronger than a 1" diameter rod.

Actually if you look at the direct pin bucket for this same loader frame....it looks to be about twice the pivot distance as the 4-bar. Reference pics in post # 116 and #120.

So they did account for the longer cylinder by giving the bucket LESS mechanical advantage over the cylinder that now has a longer rod.

Looking at the two loaders side by side....its tough to tell which one would buckle easier, since that is a function of length vs rod diameter as already been discussed...(and hopefully that horse is dead).

Obviously the rod without the 4-bar will buckle under LESS compressive load since it is LONGER and presumably the same diameter.

BUT, the mechanical advantage of the loader over that 4-bar link appears to be about twice that of the direct pin. So as in your example...point load the bucket in the 4-bar with 1000 pounds and you are putting 6000 on the cylinder. Do the SAME thing with the direct pin and you are only putting about 3000 pounds on the cylinder.

So we simply have 6000# on a short cylinder....or 3000# on a long cylinder....which one would buckle first. Thats the great mystery that cannot be solved without some better measurements which I have no way of attaining.