Definitely use hearing protection of some sort. I use ear plugs, but some folks prefer the muff style.
Also, use your seat belt!!!!! That tractor will keep on going rather your in the seat or not. There is a "dead man" switch under the seat, should you fall off the tractor. However, I'm not depending on it. I just saw some pictures of a farmer ran over by his cutter after falling off his (older) tractor. This was just before responding to this post. Not a pretty sight as you can imagine!
Brush cutting is not a job to do if you're tired or worn down by the heat (it's going to be 95° here in PA today...and I probably will be doing some cutting).
3 acres is about the same as I maintain. If you haven't mowed that area yet, go slow for the initial mowing. I use 1st and 2nd gear low range since my acreage has several rutted areas hidden by the brush. It takes longer, of course...but safety first. Anyway, I'm just not in any hurry when operating the tractor.
If you have to transport that cutter in the raised position, make sure your lower link turnbuckles are tight enough to eliminate as much sway as possible. Definitely slow down for turns when transporting...that's a considerable amount of weight extended out back of the tractor!
Personally, I rarely transport the cutter in the fully raised position. I normally just raise the front of the cutter a bit (to prevent the side shields digging in) and tow it with the tail wheel taking most of the weight.
If you have a loader on your 790, I suggest you leave it on when brush cutting. The loader counter balances the cutter nicely and leaving the bucket low (slightly in the dump position) can help find and stumps, old fence posts or other things jutting up from the ground.
My 790 has never over heated. It normally runs pretty cool even when the radiator grill is clogged with dust and pollen. Obviously, you do want to keep an eye on your temp gage though.
The 790 does real well with a 60" cutter. Personally, I think a 60" cutter is perfect for the 790. Even with that first cutting (when the brush might be really thick and tall), the only thing you may have to do is make passes that aren't the full width of the cutter. No big deal there...and the next time you mow, you can run the full width. Common sense will dictate if you need to make partial passes.
When you get your cutter, there is a procedure to engage the PTO. Pretty simple...engage at 1200-1500 RPM with the transmission in neutral. If the tractor starts to stall, just blip the foot throttle. Release the clutch and let the cutter blades extend (you'll hear a couple thumps and feel some vibration). It'll take 5-10 seconds for those blades to spin up. Once that is done, increase your RPM to PTO speed (about 2600 RPM) and engage your transmission. Definitely use a low range gear! I strongly suggest 1st gear low until you feel comfortable. After that, just go do your work.
There's also a debate rather to use a rigid top link. The first time I cleared the arcreage, I did. This year I left the top link disconnected. The 790's rockshaft lever has an adjustable stop for the lowered position. Suggest you set that so the front of the cutter (judge this by the side skirts of the cutter) is a bit lower then the aft end of the cutter. As mentioned, my area is pretty rutty. I still scalp on occasion but I do a better job with the top link not connected. My only concern with leaving the top link off is if the cutter jumped up. The PTO shaft will only collapse so far, so I cannot see the aft end of the cutter lifting to much.
One more thing...cutters are some heavy beasts! Rigging them to your lower links involves a lot of levering (use a 2x4 about 60" long) and cursing. I bought the Pat's Easy change which does reduce much of the really aggravating work. Doesn't eliminate all the hassles, but makes life much easier. After you first rig the cutter to the stock lower links, you'll know exactly what I mean. You may even invent new nicknames for your tractor, rotary cutter and life in general.
Hope this helps! That 790 is a fine machine...fits any task a small farm or residential owner needs to do. I'm sure you'll enjoy operating it as much as I do operating mine.
