Rotary Cutter 6' KK rotary cutter problem!!

[HammerFour]

Re: 6\' KK rotary cutter problem!!

I wouldn't be that concerned about the fact that the blades can hit, during operation they will be swung out and that won't be an issue.

What would very much concern me is the sudden pto engagement...as another poster mentioned, that will tear up a lot of equipment as pto attachments aren't designed to go from 0 rpm to x rpm in an instant. The inertia of the rotating parts of the cutter are what is breaking the shear bolt, same as if you hit a big stump that stopped the thing from rotating at low rpm, the effect is the same, just in reverse.

I would only use the mechanism on that tractor that let's you ease the pto up to speed, I guess you could use the sudden starting method for low inertia devices like pto pumps or generators, but I wouldn't even use it then. Mechanical systems don't like sudden starts and stops, it breaks stuff.

 

[NoTrespassing]

Re: 6\' KK rotary cutter problem!!

Could someone explain the PTO system on these tractors? When is it recommended that manual be used vs auto?

I use a 6' KK without a problem. I slowly let out the clutch on when engaging the pto. I sometimes need to lubricate the blade pivot points to make sure they extend all the way and do not fold back slightly and become unbalanced.

One possible way to avoid the problem would be to manually fold the blades in the opposite direction before engaging the pto. That way on start up they would swing to cutting position rather than swinging in to each other.

It sure sounds like the option to use the clutch to engage the pto is the real answer. Is it that much of a problem to engage it that way?

Kevin

 

[have_blue]

Re: 6\' KK rotary cutter problem!!

</font><font color="blue" class="small">( Different height.. or different length.. I'm sure that would make for some interesting design calcs.... Seems like lower leading blade would be doing most of the cutting...
Soundguy )</font>

Could be the design. Maybe the stump jumper diameter is too small and the blades are too long. I'm sitting here trying to imagine how my blades could ever touch, and I can't right now. I'll check next time I go the the tractor shed, and I may be surprised.

In Grizzman's case, looks like there is enough blame to go around. A tractor should provide a way to feather the PTO up to speed, and a cutter's blades should not ever touch.

 

[KennyV]

Re: 6\' KK rotary cutter problem!!

Wow you are having this type problem starting a rotary cutter…?
Can you imagine what would happen if you used that type of start up on something with a lot of weight /forums/images/graemlins/shocked.gif, like the rotor in a large generator or the heavy drum in a medium/large chipper shredder?
This sounds like an oversight on the tractor drive engagement … . KennyV.

 

[skipmarcy]

Re: 6\' KK rotary cutter problem!!

My Mahindra 4110 PTO system has the 1) 3 position manual lever to change from neutral to either 540 or 1000 rpms. 2) A dash mounted switch to change to either manual or auto engagement, as well as an off position 3) A steering column mounted push button switch to turn PTO on and off. In the manual mode, when you push the column mounted switch on, the PTO comes on and stays on until you push the button again. In the auto mode, you push the button on and the PTO will come on but if you push the clutch in, it will stop it until you release the clutch again. Also, raising the 3 pt. will stop the PTO once it reaches a certain height until you lower it again. The electric solenoid that is activated from the switching system causes hydraulic pressure to engage a hydraulic clutch inside the front transmission that engages the mechanical shafts to run the PTO. The input shaft that the hydraulic clutch is on runs constantly when the engine is running via a shaft that runs off the pressure plate - using the clutch pedal does not stop this shaft, you are only stopping the transmission input shaft when you push the clutch - it runs off the clutch disc. I can see no benefit in using the clutch to engage the PTO in the auto mode - you are still engaging the PTO via an electrical switch, same as if you were using the push button in the manual mode. The only benefit that I could possibly see is that you can disengage the switch more quickly with your foot on the clutch than you can pushing the button switch with your finger - maybe. As I have already stated, I haven't broken a grade 3 shear bolt in my 6' cutter in about 3 years now, and I would guess I have started that cutter well over 75 times on that same bolt. My tractor idles right about 700 or 800 rpm's and that's where I engage it 95% of the time. I have engaged it as high as 1800 rpm's a couple of times, but try not to do this often, only in severe circumstances. My old cutter has the square PTO shaft and it has alot of slop/wear in it, has a large stump jumper and 2 heavy blades and it will shear bolts when I hit something that shouldn't be hit, but my tractor has never broken a bolt in it. There is some very slim chance that something is wrong with his tractor causing the bolts to shear, but I can't imagine what it would be from my experiences. I would have to lay the blame on the implement if his tractor is indeed operating just like mine.

 

[Grizzman]

Re: 6\' KK rotary cutter problem!!

Skip

You are correct putting the PTO in Auto mode and slowly letting out the clutch, made zero difference. I took the blades off of the KK last weekend for closer examination. The blades freeswing and hit each other mid-way and on the tips. I don't see how this could be a issue with the tractors PTO. The contact is only made on engagement, once the blades are apart they work and cut fine. The first cutter did the same exact thing as second one. I engage the PTO at idle speed at 700-800 rpms range. It is frustrating to pay $800 bucks for a cutter and it has a design flaw, especially with no support from the manufacturer. I guess I will live with it until next spring. I am going to trade it in on a Bushhog or Woods Cutter.

 

[DrewL]

Re: 6\' KK rotary cutter problem!!

I have a 5ft KK and the thing is as advertised. My humble opinion is.......... to continually shear the pin upon start-up it is doing as designed, but why? Get back to basics...............something is up . I would not blame KK or the tractor untill it is determined what is going on

 

[Charolais]

Re: 6\' KK rotary cutter problem!!

Did you start it up without the blades?

 

[skipmarcy]

Re: 6\' KK rotary cutter problem!!

Grizzman - By the way, what diameter bolt are you using? My shaft uses a 7/16". I use a locnut or double-nut and leave just a little bit of slack when I tighten it up so the bolt will move back & forth maybe 1/16" or 1/8". If you are using a 3/8" or smaller bolt, maybe that's the problem. If your shaft is drilled for the smaller size, maybe you can drill it out to accept a 7/16" diameter bolt.

 

[Yalerider]

Re: 6\' KK rotary cutter problem!!

It sounds like this is a "I have a clutch engaged PTO and its better" vs. a "you have a electronic PTO and their not very good" issue. I have used both and both have their advantages and disadvantages. The fact is he has an electronic PTO like I have. I like having the switch to use either live or independant PTO. I don't have any issues shearing pins on my Land Pride 5' rotary cutter, and I don't think it is a "design flaw" in the tractor. I use a grade 5 bolt instead of a 3 so I don't shear bolts all the time when hitting small trees.