Who do I believe?

[Dalhan]

I own a Kubota 4330 Tractor and could really use a new 72" Rotary Cutter. I want to buy a Major brand Medium Duty one that can cut up to 2" in diameter. According to Kubota the 72" width is fine but the weight should not exceed 926 lbs. All the Major brands say that their Med. Cutters are fine for this and with a PTO rating at or way below mine. Woods, Rhino, and such weights are in the 1000-1100 range. What do you folks think?

 

[Tact]

I have a JD 4520 with a Woods BB72 cutter. My tractor is 53HP with a 50 HP PTO. The cutter has a 75 HP gearbox but they recommend it not cutting over 1 1/2" diameter brush on a regular basis. My tractor handles that cutter without any problem and it weighs 700 lbs. I'm sure it will cut a lot bigger saplings without any problems. If you're cutting large diameter brush on a regular basis you might want to look at the BB720 but I'm not sure about the weight. You can go to the Woods site to get what HP tractors their cutters are rated for.

 

[Bird]

Chuck, I try to never tell anyone to do anything different from what the manufacturer says to do, but just a few thoughts:

1) In my opinion, Kubota tends to be a bit conservative in their implement recommendations,
2) Do you think that weight limit of 926 pounds is
a) because more than that is too heavy for the 3-point; i.e., could damage a hydraulic cylinder,
or
b) because lifting something heavier would make the front end of the tractor too light for
steering?

If the answer is a) above, you could always keep the rear wheel(s) of the rotary cutter on the ground during transportation.

If the answer is b) above, you can add weight to the front end of the tractor, either with the front end loader or suitcase weights.

So I'd tell YOU to do what the manual says, but if it were ME, I'd go ahead and buy the rotary cutter you want.

 

[Z-Michigan]

1) In my opinion, Kubota tends to be a bit conservative in their implement recommendations,

+1

The manual for a Kubota M5040 indicates not to use a box blade larger than 72". Which is what many would say is fine for a 35hp CUT. I didn't find that very confidence inspiring.

I think you will be ok with the medium duty cutters if you have a FEL installed or are willing to consider adding a few suitcase weights on the front. No guarantees, of course!

 

[Dalhan]

I'm not really worried about the extra weight making the front end too light. My 4330 has a FEL. My real concern would be damaging the hitch cylinders with it.

 

[N80]

That would be my concern too. I'm not sure there is any way to know for sure how risky it is to exceed the hitch weight ratings.

You could consider a pull-type mower. They are a whole different animal but you could avoid potential risk to your tractor.

Having said that, I don't think I'd worry about exceeding the weight limit by 100 pounds or so. As Bird mentioned, just avoid heavy bounces with tail wheel off the ground.

 

[Z-Michigan]

Last time I checked an L4330 had a 3ph lift rating of around 2500lbs at 24" behind the balls. The cutter would have weight centered at maybe 36 to 40" behind the balls. I don't see how 1100lbs centered at that distance is going to exceed the lift rating or damage the lift cylinders. Again, I'm not guaranteeing it will work, but I personally wouldn't hesitate to try it. Most CUTs have far more rated 3ph lift than you could ever practically use.

 

[N80]

The Kubota manuals have a separate rating for the total weight of an attached implement.

 

[john_bud]

I own a Kubota 4330 Tractor and could really use a new 72" Rotary Cutter. I want to buy a Major brand Medium Duty one that can cut up to 2" in diameter. According to Kubota the 72" width is fine but the weight should not exceed 926 lbs. All the Major brands say that their Med. Cutters are fine for this and with a PTO rating at or way below mine. Woods, Rhino, and such weights are in the 1000-1100 range. What do you folks think?

I cut trails in the woods. That is hard work, so the tool of choice is a Woods BrushBull 600. The BB600 also has full front and rear chains - that's about 150+ pounds to the 1000# cutter. My tractor is a Kubota L3410 HST. It has been happily cutting 2" hardwoods and up to 4" softwoods on occasion. It is over the capacity listed, but the tractor with FEL handles it fine. No issues with steering, transport or running it. You should be fine with the BB720, or equivalent. Just keep the FEL on it, or the nose will be light.

jb

 

[hsvhobbit]

Not sure but I was told by my dealer that the concern on Kubota's part is a 'tail wagging the dog' effect. I've noticed the effect slightly with my 4630 and my 700+ lb Rhino 6 footer. If I'm going up a slight incline with the cutter raised up and then turn, the front end will skate a little. Some weights or a FEL would take care of that I believe.

 

[EddieWalker]

I have a 35 hp Century 4x4 tractor without a FEL. I've been cutting with a Landpride 72 inch medium duty bush hog for three years. Before I had the dozer, I would really push it to create trails and open up areas on my land. I've replaced the blades twice, the gear box, drive shaft and tail wheel once. I've abused it much worse then most people would, but when it breaks, I fix it and keep on going.

The HP is plenty for that sized mower, but the front end is a little light without a FEL. I've had the front tires come off the ground on steep hills to the point I couldn't turn. Nothing to it, I just back up and try a different angle.

The tractor handles the weight fine, but I don't know what it weighs. A bigger tractor would just be that much better.

Good luck,
Eddie

 

[JRobyn]

Hey Chuck,

I run a Bushhog 286 (962#) on my 4330 (also w/LA853 FEL) with no issues whatsoever. I have driven the rig several miles over rough gravel and dirt roads between my place and my BILs, in mid or high range, with the cutter raised and bouncing around, also with no issues whatsoever. I've also driven the same route with my 1400# chipper on - no issues. Maybe I'm just lucky, but I agree that Kubota's ratings are very conservative, and my dealer confirmed it when I asked them about the chipper.

 

[Dalhan]

Thanks for the replies all. Think I'll just go on ahead and get a Med Duty Cutter then. Everyone seems to be in agreement including my dealer who says it's under rated as well. Rhino TW72 seems to be the lighest of the bunch at 1029 lbs Aprox. Them Bush Hog 296 at 1095 lbs. Going to get one end of the month I guess so I'll post a few pics if anyone cares to view it.

Thanks again,

Chuck

 

[638]

Of course we want to see it.

ron

 

[Soundguy]

The Kubota manuals have a separate rating for the total weight of an attached implement.

Relief valve is suposed to be there to protect the cyl from a load that is too heavy to lift.

Soundguy

 

[Mike_VT]

I have an l4330 and run a 72 woods that is appx 1000lbs. No worries.

 

[Glowplug]

1) In my opinion, Kubota tends to be a bit conservative in their implement recommendations,

+2

You should be okay. 100lbs is not going to make a big difference. On my M7040 the weight limit recommendation for a box blade is 1200lbs. But I've seen plenty of people use 1500lb box blades with no problem. I'd go ahead and get either a Woods BB720 or Rhino TW72 if I were you. Just make sure you have adequate front-end ballast.

 

[N80]

Relief valve is suposed to be there to protect the cyl from a load that is too heavy to lift.Soundguy

I'm just saying what the manual says.

The parts manual for my tractor (which I don't have in front of me) shows some type of valve integral to the 3 pt lift piston (which is internal) housing. It does not call it a pressure relief valve. There is a pressure relief valve but it is on the front hydraulic block and only affects the loader as far as I can tell. This valve thingy for the 3 pt lift piston is called something like 'shock load absorber' or something to that effect and is a fairly large, complex looking thing. I'm assuming it has a function similar to a pressure relief valve but it does not appear, from the drawing, to by pass any fluid. But, I agree with you, there is obviously something there to dissipate shock loads on the 3 pt hydraulics. How much shock load can it withstand? Well, that takes me back to the manual, which appears to be very conservative. I'll look up the name of that part when I get home.

As an aside, I always assumed that single internal 3 pt lift pistons were for small, low end tractors and dual external pistons were for larger Ag and utility tractors. I was suprised to find that my farmer friends big JD (4430 or 4340, something like that) has a single internal piston. He had it all apart and I had a chance to look at it. Of course it was enormous and very stout.

 

[N80]

I looked it up. Its called the 'cyclinder safety valve'. Have no idea what it does. Again, assume its to relieve pressure in some way if there is a shock load. I can't really tell, but it might just be a simple pressure relief valve but can't tell from the drawings where it vents to. Probably back into the transmission case.

I don't know if the 4330 has an internal lift cylinder or external lift cylinders.

 

[Soundguy]

I looked it up. Its called the 'cyclinder safety valve'. Have no idea what it does. Again, assume its to relieve pressure in some way if there is a shock load. I can't really tell, but it might just be a simple pressure relief valve but can't tell from the drawings where it vents to. Probably back into the transmission case.

I don't know if the 4330 has an internal lift cylinder or external lift cylinders.

Quite possible it exhaust right into the open housing.

And yes.. external lift pistons are generally the exception.. not the rule.. even up into the 100hp tractors. my NH 7610s tractor has an internal lift piston..

Now once you get into crazy large machines.. then you never know what you will see...

Soundguy