Anyone ever actually blow out a hydro drive, having used the mower for nothing but mowing?
Well, yes and no. I blew one out on a Toro TimeCutterZ 1752...pretty much a residential mower, although it was better built than the residential grade ones now are. But it had all-in-one HydroGear brand hydros, sealed drive units, no drain, no filter. Wouldn't have bought it if I had know this little fact, shame on me for not doing my homework.
To be fair, I pulled a pretty big lawn roller with it at least once a year...and my yard is not flat, I ran it pretty hard for 7 years. Should have known better, but the dealer told me when I bought it that it should be fine for pulling a roller.
The first time I rebuilt it, it had pretty much grenaded itself due to the oil being full of metal shavings, it took a new pump, new motor, new bearings and seals. It talked to the mechanic at the dealership, he told me to put full synthetic oil in it. I pulled the other side out and did a drain/flush/refill with synthetic too...the oil was clean in that one (right side)
7 years later, and no more lawn rolling, I'm sidehilling mowing the ditch out front, all of a sudden it quits driving on the downhill side (left side) I look back and see a trail of oil. The axle shaft carrier bearing went out, took the seal out, puked the oil all over. The pump and motor were OK this time, so I installed a new bearing and seal, then went to shopping for something a little beefier.
After finding a nice low hour Hustler Mini-Z (smaller, but just as beefy version of the SuperZ) with heavy duty White brand hydros, the Toro went down the road to a new happy homeowner with a pretty flat yard...he was warned to not tow lawn rollers with it. Oh, and the second time I drilled and tapped the cases for oil drain plugs too.
When I looked at the Hustler it had a small oil leak on the left hydro motor, the owner said the guy at his shop said to pop the brake drum off and pop a new seal in it...so after I bought it, I did. Before I was done with the first mowing...POP, new seal was out! Turns out, this outer seal was not meant to hold any hydraulic pressure, and the inner high pressure seal was actually the culprit. So long story short, I got to see the inside of the White brand drive motors the Hustler has...MUCH heavier duty than what was in the Toro!
Bottom line is this...its all about what the hydros are built for. There are lots of super heavy duty hydro drives out their in millions of pieces of large ag and construction equipment that will take years and years, thousands of hours of utter abuse just fine.
On lawn mowers, if they are cheap drives like my Toro had, better baby them. If you have a more expensive unit with HD hydros, they will take a lot more abuse. I would say if you have a sealed drive system, be careful, if you can change the oil and filter, you have a better drive system and it would probably take pulling a small trailer, lawn roller, or something like that no problem (using some common sense of course)
But even with my Toro I would not have hesitated to move the log splitter around once in a while...heck I move my splitter by hand usually, they push pretty easy. The lawn roller on the other hand...can barely budge it by hand.
BTW, I built a nice HD receiver hitch for the Hustler...it will pull a pretty impressive load as long as there is not too much down pressure on the hitch...wheelies pretty easily if there is...