Double Blades on Rotary Cutters...

[Richard]

I debate on buying a new (or used if I could find what I'd like) rotary cutter. Current unit is a 15' hydraulically powered unit (pump hanging off PTO powers the blades)

I've seen Schulte which might have DUAL blades, ostensibly for better mulching.

What I don't know though is this really designed for someone who wants to chop up their corn stalks or, would it work just as well in a grassy field with growth say, four feet high?

If I get into what I'll call "normal" growth, my unit will cut and chop up most of what it drives over. If however, I get into some thick growth, then it will tend to bend the grass over, cut it and the grass clumps up, coming out the back not very well mulched. (i realize this isn't a mulching mower)

Saw the dual blades that can be done on the Schulte. No idea of other brands can do this (can they?)

What gain is there for the double blades when simply cutting grassy fields?

 

[Slowpoke Slim]

I'm guessing it's the hydraulic motor on your mower slowing down when you get in to the really heavy stuff.

Slowing down blade speed has a big effect on cutting efficiency.

I don't think adding more blades to the same scenario will help anything. Perhaps going to a pto driven mower, instead of hydraulic would help? Matching mower size to your available pto hp? 15' is a lot of mower to power hydraulically. What are you powering it with hp wise? What is the hydraulic pump rated for?

 

[Richard]

I don't know factually what the unit is rated for....I THINK the newer versions (made by Alamo) are rated for a minimum PTO of 75-80'ish HP. My IH is (I think) about 125 so that shouldn't be a major issue.

This is an old unit.....I've rebuilt all three of the motors AND the pump itself. Not saying I did a perfect job as I had never done a hydraulic pump before.. New pressure reliefs and I did something right as now, every now & then, I'll hear a bit of a whine and know that's the relief squealing out loud.

Still.....you are correct in that the blades are slowing down in the thick/heavy stuff. If I go over it again, it's obliterated to smithereens.

Interestingly (to me anyway) it's really just one of three blade sets that suffer this slowdown. Further interesting to me, it's the passenger side, outer blade. This unit gets the DIRECT feed from the pump and then goes to the drivers side outer blades and THOSE mince things up while the first set slow down.

I'm guessing the motor on that set is worn more than the others as the second blade set can't dice things up better than the first set if BOTH are getting good pressure.

If I'm getting some internal leakage in the first set, that pressure/volume still goes to the second.... so this is why I'm contemplating a new mower all together. Do I want to get into the process of replacing the motors? (don't know yet, also, have no idea of their expense.... it might be cost effective to replace them verses a new mower!!)

 

[Richard]

Current version.... I have the great great great grandfather of this! Mine is a "Terrain King"

Falcon 15

www.alamo-industrial.com

 

[Richard]

The rest of the story...

Went out today to cut a field. One side was not cutting well. Ended up overlapping so I was only cutting 10' with a 15' mower. Got to thinking about the hydraulic motor... THEN dawned on me could it be slipping past the relief valve on the motor? I need to swap them.

Drove home, parked machine went back to assess the relief valve (which all three were replaced with new ones about 1 1/2 years ago)

Hmmmm... I notice some dampness under it. Something is leaking? Looking for the drip, it seems to be coming from the relief valve.

Wha??

Looking further into it I discovered the adjuster on the valve had become loosened a bit. Meaning, the relief value was bleeding pressure off so it WAS weakened.

I have no way to measure the setting so I eyeballed it to show the same threads on this one as the other two. Tightened it up, pressure is up and it's back to cutting like a monster.