L3940 rotary cutter capacity

[mcguyverkodiak]

I am going through several older Alamo A60 and A72's and two 60" BushWhacker rotary cutters. These are heavy duty mowers. I think the 5 footers weigh 930lbs and the 72" weighs 1160lbs. The gear boxes are massive. I am worried the bigger Alamo 6' is too much for my L3940. The big stump jumper weighs 71 lbs alone without the 24" x 4" blades. Does anyone operate that big of cutter with this tractor? I do have a FEL but I am worried about overheating the motor. I am several hp shy of the minimum 40 hp it calls for.
The cutters are free to me except of several days of labor on them.
I may be selling the bigger ones and moving down to a lighter one.

 

[gsganzer]

I like to be able to mow with the FEL off, unless I'm on an unfamiliar field and need the FEL to "probe" for obstructions. It's just a smoother ride and you don't have the FEL bouncing around.

That being said, I have a L3800 and use a Landpride 2060. I feel like I have plenty of horsepower to go to a 72", but I don't have the tractor weight or 3-pt lift capacity.

With your heavier machine, I think you'd be fine with a 72". The 6HP/ft guide is just that, a guide. You can always mow slower or take less of a bite if you're in the thick stuff.

Another consideration is your tractor width. My 60" is exactly the width of my machine with R4's and I'm fine with that. But an extra 6" on each side wouldn't be bad either for getting closer to fence lines etc.

 

[Grandad4]

You haven't said anything about what you will be doing with the cutter and the L3940. If it's periodic mowing of an open, basically smooth field, the L3940 would probably run your big cutter under those conditions, but you likely wouldn't need or want a severe duty cutter like that for such work.

If you're planning to use it mainly doing the things it was designed for, that's also going to be hard on just about any tractor. For that kind of work, using a tractor with more power, weight and ground clearance, among other things, would be a better choice, IMHO.

 

[mcguyverkodiak]

Thanks for the reply. I was wanting to ask about slip clutches for the heavier cutters. Our local farm store carries Weasler and the only one they stock is a two disc plate part number 560-6006. I've seen Landpride has 4 disc on their slip clutches. The Weasler looks kinda a small. Do you think I need to step up to the 4 plate one? I'm only pushing 34 hp though.

 

[gsganzer]

I don't have any experience with slip clutches, so can't help you there. In my opinion, I'm fine with shear pins on a brush cutter. I engage it at low RPM's and have a clutch, so I don't have much driveline slap that might be an issue with a larger/mower. If I hit something hard enough to shear a pin, I probably want to get off and inspect things anyway.

I can definitely see the need for a slip clutch on a tiller with rocky soil, but I'm not as sold for one on a brush cutter, especially if you mow the same fields all the time. I could buy a lot of shear pins for the price of a slip clutch and I don't have to maintain and adjust a shear pin.

 

[Grandad4]

Either the shear bolts or a slip clutch can work; it's again entirely a matter of usage. My neighbors have used old beater cutters with shear bolts for many years. They're not too careful about what they run over with them, and they eat lots of shear bolts. My cutter has a slip clutch but we seldom put it to work because our mowing is open fields that we know well. We could get by without the slip clutch but the neighbors would save themselves many headaches if their 'hog had one.