I never got anywhere near them. My only real bad no brake situation was a 980. The right pedal was for going fast and if you were on a hill, the left pedal was for going a whole lot faster
I only loaded trucks a few times with it it was a joy try and find a hill to load up hill.
I had a 988b for mining the rock for the crusher at the dam job, but I lost the transmission seal on that and had to feed the crusher with the no brake 980 with two different size front tires. It look like a farmer was down there in the pit plowing.
If I downshifted all the way as I came up on the grizzly and dumped in first gear everything was cool I could get it in reverse and back down. unfortunately the only place to back was towards the river and there was a little 3-ft safety birm between me and a really long bad roll.
One day I forgot to go from second to first and I killed the engine. Buckets in the air, rolling back up on that little birm, restarting my heart. I went to the mechanic and begged for him to give me any brake just a little bit of brake. Sure enough he did.