I just cut about 2 acres of wooded meadow and surroundings last weekend at my remote property. The grass and weeds were about 3 to 4 feet high. I checked out the blades and bolts on the 6' Howse rotary cutter before I started and also the gear oil level. Then sharpened the blades a tad and hooked it up.
Here's a picture before:
And one after I got done.
I had to cut between the trees on the perimeter of the meadow, going forward and backwards at times. I have a 55 hp gear tranny Kama 554 with 540 PTO rpm at 2300 engine rpm in the 540 PTO speed. I have 2 PTO speeds, 540 and 720 rpm.
Here's another view:
I can't go too fast because the terrain is not flat. In fact, it is my food plot, so there are several natural swells and gullies and a steep bank on one side. I mow in 2nd or 3rd low, and using 1 low reverse to cut up the steep bank.
I cut all this terrain at 1725 engine rpm with my PTO in the 720 range. That means the PTO is spinning at 540 rpm, which is perfect for my rotary cutter. This engine rpm range also just happens to fall in the engine's peak torque range (or very very close to it). So when it feels a strain, it pulls through it with very little bog down at all. Additionally, I get much better fuel economy. It took me about 4 hours to finish everything, going around the trees, gullies and banks.
To give you an idea of what it looked like when still green, check this out.
I had cut a part of it a month ago when it was still green to generate some interest for the wildlife.
IMO, there is nothing wrong with using lower rpm when mowing. In fact, I would go as far to say the lower rpm you can get away with, the better for a number of reasons. Fuel economy and wear and tear on the tractor AND your rotary cutter are a couple of them. The flip side is how fast you want to get it done , of course.
I could have used lower engine rpm on the down hill passes, but although it does not look very sloped, it is. So going uphill I needed to keep the engine rpm at a reasonable point to generate enough hp to keep her going. I would say your limiters are the kind of terrain and what you are cutting determines the hp needed, and the outcome of the cut. That is, is it desirable and acceptable to you. That in turn will tell you if the PTO rpm is correct for YOUR job.
