On 07/29/2015 9:51 AM, dpb wrote:
....

Just guessing, but a first shot approximation...

From the size of the tractor, and giving benefit that the 3-pt is Cat
1, not Cat 0, I'm guesstimating by measuring from the pictures that the
arm is 1", 1/8"T tubing and roughly 16" long from the gusset to the lift
point. If so, from the following calculator, the bending stress approach
30k psi for a load of 200 lb. ...

And, of course, that's static loading only; the real kicker on stuff for
usage like this is the impact loads that are applied when the tractor
hits a bump or the like; those can be several times the static loading
and without any springs or other absorbing mechanism, it all has to be
taken up by the "beef" of the structure.

An example is the little 3-pt sprayer (55 gal) capacity...it was
commercial from Schaben but didn't take but one or two summers over the
ground around the feedlots and machinery parking areas before the bounce
caused the boom arm folding connectors to crack as well as the 6" wide
1/8"T rolled main support under the tank started to tear. I added a
1-1/2" by 5/32T angle; it still wasn't enough to take more than another
couple of years. I've got to beef it up again further this year and
will at that point also find some heavy compression springs to set the
tank on to relieve some of the impact load from being transmitted
directly to the frame.

While you'll never move stuff around with the hook like one covers
ground at a steady pace while spraying, it's inevitable you _will_ find
a hole or somesuch...

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