Berta flail mower

   / Berta flail mower #1  


Silver Member
Apr 14, 2012
BCS 740
Hi :)

After long considerations, I recently decided to order a Berta flail mower with 85 cm (34'') working width for my BCS 740. The mower has arrived, and I would like to pass on some of my experiences setting up the mower, and hope that this information can be useful to other Berta flail mower owners.

As I have the quick coupling on my tractor, I got the mower with the Berta factory built-in male quick coupling flange as well. As this coupling has an elongated hole for the locking pin to drop in, it allows the mower to pivot a little, and thereby better follow the terrain independently of the tractor, compared to a rigid standard coupling. Should this pivot feature for some reason not be desired, the mower came with two Allan-head bolts that can be mounted in the male quick coupling, making it work like a rigid standard coupling.

As 2-wheel tractors come with different PTO-heights and wheel diameters, the mower has a feature that allows the body of the mower, called the "main bonnet" in the manual, to be adjusted accordingly, thereby allowing the mower to run parallel to the ground. 3 different settings are available, and the factory standard center setting fits a BCS tractor with standard 20'' wheels I think, but with my 23'' wheels, the mower had a distinct nose-down attitude, preventing the roller at the back of the mower to even touch the ground!

In the 44-page user and maintenance manual that comes with the mower, the setting of the PTO position is explained and illustrated. I followed the description and the illustrations to the dot, but to my surprise, I wasn't able to move the body/main bonnet at all! After a bit of investigation, trying to figure out how the frame of the mower, called the "angle unit" in the manual, is connected to the body, I noticed a bolt on the mower that isn't mentioned in the manual. After loosening this bolt slightly, I could easily adjust the PTO position :thumbsup:

Among his many instructive and useful videos on YouTube, Joel from Earth Tools also has a video where he tells about the setup, the main features and the maintenance of the Berta flail mower:

Berta flail mower for walk-behind tractor--Setup, features & basic maintenance - YouTube

Although Joel shortly mention the feature allowing you to adjust the PTO-height of the mower to fit your tractor, he sadly doesn't show how it's done. As I found the description in my manual slightly erroneous and misleading, I will try to tell how I did it:

I connected the mower to the tractor, and removed the left and right protection cover in order to get access to the bolts underneath. This is how it looks under the left protection cover:

DSC05636 (2).jpg

The mower looks the same under the right protection cover, except for the 2 belts and their pulleys transferring power to the rotor shaft. In the manual the figures shows the right hand side of the mower, and therefore some of the nuts are hidden by the belt and pulleys. To get a better view, I decided to tage my foto from the left hand side.

According to the manual, one shall remove the 3 lock bolts which I have marked in white on either side of the mower. Then loosen the nut marked with green, and you should be able to adjust the main body of the mower - but you can't! You also need to loosen the nut that I have marked in red. With the 23'' wheels, the lowest setting will allow the mower to run almost parallel to the ground, so that is the one that I have chosen. Then reinsert the 3 bolts marked in white, and tighten the 2 nuts marked in green and red.

This setting of the PTO-height only has to be done once when receiving the mower - except in case one changes the wheel size on the tractor, of course.

The manual also instruct you to loosen the 4 nuts securing the rotor bearing (the nuts between the red and green circles on the foto), in order to be able to adjust the PTO-height. I could easily do the adjustment without loosening these 4 bolts though. The manual also instruct you to unscrew and remove the rear cover between the main body and the connection flange before doing the above mentioned adjustment (this is the cover with the hole in it for the dipstick). This is to my knowledge also a needless action, as the cover is part of the "angle unit" and therefore moves with the side frame.

I have been very puzzled by the manual on this topic, and perhaps I have missed an important point somewhere. Having spent quite some time in my garage with the Berta flail doing the PTO-height adjustment and preparing this post, I get the impression, that the manual was perhaps written by someone with little hands-on experience with the mower. The version number of my manual is 01/2010, which might indicate that this version has been around for 10 years now. I therefore find it difficult to believe, that I should be the first owner to have stumbled over the above mentioned discrepancies?

Finally a few words regarding the cutting height adjustment:

By adjusting the rear roller up or down, the cutting height can be adjusted accordingly. The roller is fixed to the main body by 2 bolts on either side of the mower. The forward most bolt can be set at 2 different heights, whereas the one at the back can be set at 5 different heights. This should in theory allow for 10 different combinations. I have been able to select all 5 settings at the back, with the forward most bolt in its upper hole. With the forward bolt in its lower setting though, I was only able to select the 2 lower of the 5 holes at the rear. That adds up to a total of 7 settings.

Now I'm looking forward for spring to arrive, allowing me to test my new toy in the real world out there ;)

Best regards

   / Berta flail mower #2  
Excellent write up! Thank you for these instructions. I have the older 34" Pallatino flail mower. It is wonderful what a flail mower can do. The Berta flail appears to be a well engineered design having several advantages over older flail designs. We look forward to hearing of your experiences with the Berta flail.
   / Berta flail mower #3  
I have the same Berta mower and it works GREAT! Love it for tight area where the tractor does not fit or is not safe to use. I think you will be pleased when you use it the first time!
   / Berta flail mower #4  
Thank you Jens :thumbsup:
We have been using our Berta 26" for one season (2019), it is a great machine! We are trying to get away from animal based fertilizers so we are cover-cropping and flailing all our gardens.
We bought our mower directly from EarthTools. It didn't require any leveling adjustment to fit our BCS732. We also used it to clear a path outside our electric fence, worked way better than a regular mower, the weeds took a lot longer to grow back + less places for the bears to hide :laughing:
   / Berta flail mower #5  
Thanks Jens. You’ll love it. We have the Berta 30” connected to a grillo 110. Ours arrived fully adjusted from earth tools. You might consider removing the baffle if it is installed. The flail is great for light brush and below but I find that the rotary disc super duty Bellon mower is better for saplings. Ideally you’d have both but neither is cheap. Watch out for vines, wire and cable! The flails really don’t mis well with those. But flails are excellent at not throwing rocks. They seem to like full throttle the best.
   / Berta flail mower
  • Thread Starter
Hi 😊

I have now had the chance to use my Berta flail mower for a total of 9 hours, and will like to share what I have learned until now with you.

A number of members have already been so kind to share their experiences with all of us, so perhaps there is not much that I can add. On the other hand, I have perhaps used my mower for jobs that are not that common, so I perhaps there is 🤔

I my little municipality, I am a member of a group of people who are taking care of 12 smaller nature reserves, which are home to a number of rare plants and animals. Some of the plants and animals (especially insects) living there, are listed as threatened species, and therefore protected by law. We have a handful of different orchids for instance, and a number of butterflies, and a snake. Sadly, some species of orchids for instance, have become so rare that we only have 1-3 plants in total in my entire county! 😢

Part of the fauna here is the wild boar, which has increased dramatically in numbers over the last decades. When searching for food, the boar will dig into the ground with its strong snout, a thereby turn the sod upside-down. This is a totally normal behaviour, but very unfortunate when it happens on a meadow with very rare plants. As we are mowing these meadows once a year with a 2-wheel tractor with a sickle bar mower, we need to flatten the damaged areas in late winter/early spring. Doing this by hand is a very exhausting job, so in early spring I did a little test with the Berta flail, and it did a really good job 👍

My idea was to set the cutting height of the mower so low, that the sods that were turned over would be cut into small pieces, and thereby hopefully fill up some of the holes at the same time. After a bit of trial and error, I finally had a good cutting height setting, with the forward most bolts in the upper holes, and the bolts at the back, in the center holes. On my garage floor, this gave a cutting height around 22 mm (just short of 1''), with my BCS 740 on 23'' wheels.

While I was in the garage, I tried out the highest and lowest setting of the rear roller. With the roller in its lowest position, the cutting height is around 50 mm (2''), and in its highest setting, around 8 mm.

Having the cutting height set at only 8 mm, I decided to test if the flail mower would work a bit like a scarifier on my lawn. Of course it didn't do the job of a proper scarifier, but my neighbour was at least so impressed, that he wanted me to do his lawn as well 👍

Best regards

   / Berta flail mower #7  
Hi 😊

Having the cutting height set at only 8 mm, I decided to test if the flail mower would work a bit like a scarifier on my lawn. Of course it didn't do the job of a proper scarifier, but my neighbour was at least so impressed, that he wanted me to do his lawn as well 👍

Best regards


Jens, thank you for the excellent write up and information on your experience. On the point of the 都carifier? I think you probably mean what we might call a de-thatcher. You might know this but special flail knives are available for this purpose. They do not have a bend and do not cut grass or brush. Rather, they cut down into the sod and are designed to lift up the thatch. I have never used one for this purpose so i cannot comment on effectiveness. Have fun with your useful tool!
   / Berta flail mower #8  
Can you tell me the dimension of the y blades?
   / Berta flail mower #9  
Check the flailmaster catalogue. Exact dimensions given. There are a variety of different knives that can be used. The renovator knives are de-thatcher/scarifier knives. Good luck.
   / Berta flail mower #10  
berta have a one-way ratchet inside? i want to use with a grillo g 110 and the pto direction actually reverses when the tractor is put into reverse.