So now getting back on topic - this thread was never supposed to be about the physics of ballast. I actually assumed that everyone was on the same page with the general principles.
I still want to know if anyone has actually "trashed" a front axle, or had premature wear issues, from running too little ballast on the 3pt?
We have one broken axle example so far but that sounds like ballast on the 3pt might not help if you decide to wedge the front end between the earth and a tree trunk and keep driving forward.
(That example would actually be fun to talk about in terms of physics because I can see how several multiples of the tractor's actual weight could be applied to the front axle.)
The real issue is that our tractors are front wheel assist, not true 4wd. The front axle shafts and ring and pinion are meant to only assist in propelling the tractor along the ground. If you lack adequate ballast and the rear tires are essentially in the air, and you push hard or perhaps back up a steep slope with a full bucket and the front axle doing all the work, that is when you snap an axle shaft or strip the ring gear or pinion. It is designed for a load of X and we are asking it to do 4X. Having adequate ballast helps keep the rear tires in the mix all the time for tractive force. The
rear ring gear and pinion and shafts are much more robust.
Guys will break front axle shafts and gears, and we can tell them what they were doing when it broke. They were in some manner putting a huge load on the front axle, the front axle had superb traction, and they were trying to move the tractor in a extremely high load situation.
Example 1: Put the bucket under a stubborn stump, lift with the bucket until the back end is pretty much off the ground, now hammer forward and see what happens. Here are the options: 1) The stump gives way. 2) The engine dies. 3) The clutch slips. 4) The front tires spin. 5) Something breaks. No other options. And we have a lot of torque with our low gearing, so the engine generally won't die, clutches generally do not let go with low gearing, the front tires have maximum traction. Pop goes the ring gear, or if you are lucky, just a shaft. Now I'll admit that rear ballast doesn't solve "stupid", but it does help in many situations....but probably not in this stump scenario.
Example 2: Backing up a steep creek bank or pond bank with a fully loaded bucket and the rear tires essentially out of the mix. A full size commercial machine or a wheel loader can do this all day long. A CUT is somewhat at risk. Although this is a better scenario then the "stump" as there is still a chance that the front tires will spin before you have breakage. A gentle operator can do this with a CUT, but it does put a bunch of load on the front axle gears/shafts. In this scenario, rear ballast will definitely help save the front axle from gear/shaft damage.
I hope this was helpful. If we understand how and why things break, we tend to break things less often.
