Duke,
The walk behind cutters are different from the 3ph rough cutters in several ways:
Though self-propelled, you can feel like you're wrestling a gorilla when trying to steer in and out of corners and over little bumps. If it's bumpy AND curvy, it's even worse. On a hst tractor with 3ph pto driven rc, you have very fine control over the movement and can sit calmly rather than fighting the machine.
The self-propelled units just have an oversized one piece lawn mower blade. The unit can stall much more easily than a brush hog. The 3ph pto rc has a spindle pan. On this pan are attached 2 extremely thick, heavy blades which look like the mother of all meat cleavers on steroids. The 2 blades are opposite each other and are attached to the pan by pivot pins. The walk behind depends on direct "at that moment" power from the engine. The 3ph pto rc builds up a tremendous amount of kinetic energy in its heavy blades. Energy is being put into the blades in "real time", but the tremendous energy already in the blades is where the greatest force is. When the 3ph pto rc blade hits something with great resistance, the pivot pin allows the blade to slide off at an angle, then whiplash back out. The pan does not slow down. On the walk behind, if the one solid blade hits something with real resistance, the entire driveline back to the engine begins to slow and the engine can partially or fully stall. I can run over a stand of 2" saplings with my
BX2200 and 42" GearMore rc and not lose 1 rpm.
Your 17 pto hp. put into a 42" 3ph pto rc will cut a wider path than the walk behind. You can get a 3ph pto rc at 36", 42", 48", 60", 72" and on up in 1 ft increments. I'd say 36", 42", or 48" would be appropriate for your combination of tractor size and your need to back the unit into small spaces. In an open field of hay, the 60" might be O.K. for you.
My 42" GearMore was under $700. I'm sure you know the price on the DR and Swisher, etc.
You already have a diesel engine as a power source. Do you want to maintain another gasoline engine that you use once every 1 or 2 years. Gas engines that sit idly are a pain to maintain and prep for use after sitting long periods.
The typical rc does not come in offset positions. Those that do are much larger than your tractor acommodates and are pricey. Small flail mowers are hard to find, but they are available. While browsing last night, I saw a 47" one that required less than 17 hp. Most flail mowers can be offset.
A sicklebar looks like one comb on top of another, except there are sharp blades rather than teeth. The 2 "combs" slide back and forth with all the teeth making numerous scissor like cuts. Troy-Built has one that's walk behind & self propelled (another gorilla wrestler). On a tractor, the blade extends from the 3ph perpendicularly to the side. Most are 8 to 10 feet long though. You see them on big tractors cutting the roadside grass sometimes. I don't think you can find one for the dimensions and size you need.
