Berta Flail Mower stops running in high thick grass

   / Berta Flail Mower stops running in high thick grass #11  
No mower except a sickle ever likes lush tall grass. When I cut fields with my flail, I waited for the grass to dry out in the fall, and cut the fields then. Or, I would have had to cut it bi-weekly at worst and weekly at best, to stay on top of it, which wasn't an option.

Few mowers work well when you raise them too high.

I have a sickle mower and I tried it a few times because it is faster than the flail mower, but the problem is that my ground is so uneven that it causes the much lighter sickle mower to bounce around in turn causing me to miss parts of what I am trying to mow. Also, the flail mower mulches what I am mowing much better as where the sickle mower just lays it down with no mulching.
 
   / Berta Flail Mower stops running in high thick grass #12  
Another question: I have the Grillo with 5.12 wheels, should i lower the main shaft of the Berta flail mower?

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Hello Anastasie,

I would not lower the mowing height of the BERTA flail mower rotor until the grass/brush stops growing as you will still have issues with tangling wrapping stringy weed stalks/grass and cat tails.
 
   / Berta Flail Mower stops running in high thick grass #13  
There is excellent advice in the thread already, but some other potential solutions:

As already noted, wait until a few days of hot weather to mow while grass is dry. Set to first gear, mow one strip, then mow in higher gears taking less than a full strip of grass to reduce load. I have been able to cut tall grass without messing with height adjustment with my Berta. Usually, it's bad in only a couple of areas, and the mower can handle it at full speed in others. If your is all too tall and you cannot wait for it to dry out a bit, then Leonz' staged solution is likely the best way to proceed.
 
   / Berta Flail Mower stops running in high thick grass
  • Thread Starter
#14  
Thank you again sirs! I will not meddle with the machine :)

God bless you!
 
   / Berta Flail Mower stops running in high thick grass #15  
Hi anastasie ;)

Based on my approximately 50 hours of experience with the 85 cm Berta flail mower powered by a BCS 740, I think you are pushing your tractor and mower to the limits and perhaps expecting a little too much of both of them :unsure:

Mowing tall, dense - and perhaps also wet grass, is a tough job for any flail mower, as it does not only cut the grass, but also has to cut it into small pieces. This is a very power consuming process, compared to simply mowing the grass with for instance a sickle bar mower.

The fact that your flail mower and tractor wheels both stop rotating, indicate that your clutch is torque overloaded and therefore slipping, as the PTO and the wheels are powered through the same clutch. If only the mower stopped rotating, while the tractor kept on moving, I would expect the 2 V-belts on the Berta to be slipping. The high pitch sound that you hear, is the clutch crying out loud for mercy :cry:

My feeling is that there is nothing wrong with your Grillo or your Berta - you are only pushing both of them pretty hard :unsure:

When mowing with a flail mower in tough conditions like yours, it is important to run the engine at full open trottle and at maximum speed (3600 rpm), in order to get the rated power output (11.7 hp). The Grillo company has designed the clutch to cope with the torque produced under these conditions I’m sure. If you overload your tractor though, engine speed and power output will drop - but engine torque will rise! If you allow engine speed to drop to 2500 rpm - still with full open trottle - the engine will reach its peak torque value, which might be more than the clutch is build for. By allowing the clutch to slip, the entire powertrain is protected against overload and possible failure. If engine speed drops below 2500 rpm, both power and torque will drop, and if the load isn’t reduced, the engine will finally stall. For a more detailed explanation, you might want to read this thread: Gasoline versus diesel

A high engine speed is also important in order to keep the hinged knives in their mowing position. If engine speed - and thereby the speed of the rotor - is allowed to drop, the centrifugal force on the knives will drop, reducing their ability to cut the grass and keep themselves clean. You end up in a vicious circle, where the risk that the grass will wrap around the rotor increases, because the knives will have less power to cut it and to keep themselves clean.

In order to reduce the load on your tractor, you could adjust the support roller to the lowest position, giving you the highest cutting hight for the first cut. If needed, you can reduce the cutting hight in subsequent cuts, until you have reached your desired cutting hight.

As your Grillo G110D is equipped with the 5x12x22’’ wheels, I would definitely adjusting the Berta to better fit your wheel size! But please note, that you should raise the PTO-flange on the mower - not lower it! (Page 21 in the Berta User and Maintenance Manual) :oops:

My recommendations:
  • In tough conditions always run the engine at or close to full throttle in order to get peak power
  • Do not allow engine speed to drop too much - reduce load
  • Begin mowing in 1st gear and where the grass is shortest and less dense
  • Consider mowing tough spots with a lot of overlap
  • Adjust the roller for the highest possible cutting hight
  • Mow only when the grass is dry
  • Remove the rear deflector/baffle, if you have it in place
I hope this helps a little, and that you will have a lot of pleasure with your Berta ;)


Best regards

Jens
 
   / Berta Flail Mower stops running in high thick grass
  • Thread Starter
#16  
Thank you very Much Jens767!!!

I will take in consideration what you wrote!!!

Could i ask a question?
Do you sharpen the Berta flail blades? If yes, what is your tehnique?

My brother sharpened them and he says that machine is goind pretty smooth now... but i have mixed feelings about this.

Thank you again and God bless you,

Anastasie
 
   / Berta Flail Mower stops running in high thick grass #17  
I sharpen mine on a bench grinder. I lean the flail mower on it's side and the knives came out pretty easily. A five or ten seconds on each knife to grind away the dents and it worked much better afterwards.

I was careful to take as little material off as possible to help keep the balance consistent.
 
   / Berta Flail Mower stops running in high thick grass
  • Thread Starter
#18  
My brother did the same. Thank you!!!!!!!!!!1
I sharpen mine on a bench grinder. I lean the flail mower on it's side and the knives came out pretty easily. A five or ten seconds on each knife to grind away the dents and it worked much better afterwards.

I was careful to take as little material off as possible to help keep the balance consistent.
 
   / Berta Flail Mower stops running in high thick grass #19  
Hi again Anastasie ;)

I’m glad that you could use my information :)

Like you, I also have mixed feelings when it comes to sharpening the knives - not only on a flail mower - but on many types of mowers basically. Like so often in life, there are probably good arguments for, and also against sharpening, as well as a personal preference of course.

I haven’t sharpened the knives on my Berta yet, but I have considered if I should. The professional gardener who have cut my meadow for 5 years with his drum mower, has never sharpened the knives, and they seem to work just fine. This doesn’t mean that it is the best choice, but it has made me a bit more reluctant as well.

On the other hand, I have sharpened the knives on my Zanon ZCR lawn mower each winter, and that has worked fine. Sharpened knives makes a cleaner cut, and they also need less power when cutting. That is probably what your brother has noticed as well, and what we all know from working with a dull pocket knive for instance. A sharpened knive is at the same time more vulnerable to foreign objects due to its sharper thinner edge, so if you are doing a lot of „rock mowing“, I would be even more reluctant to sharpen the knives.

When I work with my lawn mower I hardly ever hit any foreign objects, as I have set the cutting hight to 8 cm, and therefore I sharpen the knives on that mower. On my flail mower on the other hand, I more often mow into the ground or hit an obstacle, and therefore I haven’t sharpened that one yet.


Best regards

Jens
 
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   / Berta Flail Mower stops running in high thick grass
  • Thread Starter
#20  
Thank you again!

Merry Christmas and a happy and fruitful year to everybody!
 
 
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