Berta flail mower

   / Berta flail mower
  • Thread Starter
Hi ;)

A few times during the mowing season, I like to give my Berta a good wash down with the garden hose. I do the same at the end of the season, before stowing the mower for the winter. I hope, that keeping the mower clean, well greased and stored in a dry garage, will keep it running well for many years to come. At the same time, it is a good opportunity to check the blades, the bolts and nuts, and the general condition of the implement.

Usually I have disconnected the flail mower from the tractor and raised it to vertical, letting the mower rest on the left-hand side panel. This way the right-hand side panel with the two belts will be at the very top, where they are best protected from the water spray and dirt. This is how the mower typically looks after the wash, with quite a lot of dirt now lying on the ground:


Once as I did this washing, I recalled a video from Earth Tools, where Joel is turning the mower on its side, while it is still connected to the tractor. This might be convenient in some situations, but Joel says that you can’t do that on all the flail mower sizes:

That is correct, as you will run out of ground clearance under the engine before the mower reaches vertical with the wider models, if the tractor is on the standard 5x10x20’’ wheels. I have the 6.5x12x23’’ wheels on mine, so I decided to give it a try with my 34’’ Berta - and it works:


It is a tight fit though, as the engine is sitting firm on the ground in this picture. It only works well this way, as the right-hand side cover is more than an inch wider than the left-hand side one!

Best regards

   / Berta flail mower #82  
It looks like you have the factory wheel weights there too Jens. That's a nice set up. I don't think you could get any more traction than that. Unless you have the foam filled tires. With all my weights, I have 230lbs additional to my 739. I think the whole thing tips the scales at a little over 500lbs with all the weights. (Excuse the English units.) Pushes a remarkable amount of snow. Will get stuck from sinking in deep mud without duals though.

I forget whether you said: Did you need any wheel extensions to mount those bigger tires?
   / Berta flail mower
  • Thread Starter
Hi again Nibbana 😉

You are right, I have 15 kg (33lbs) factory cast-iron weights mounted on each wheel. I use my tractor for mowing and sweeping, and hardly ever run out of traction with this setup, which also add to the tractors stability when working on slopes. I also think this is a good compromise when mowing, as the tires don’t leave too many/deep ruts when mowing on soft terrain, while still providing enough traction.

If I remember correctly from some of your pictures, you also use your tractor with a disk harrow and other soil working implements. With such implements, you probably often need all the traction you can get, and here your additional 230lbs really makes sense. The downside is of course the wheels tendency to sink in deep mud. This again just shows how difficult and complex the topic of ballasting a tractor is in real life.

As I got the 6.5x12x23’’ wheels, I wanted to add them to the original 5x10x20’’ wheels that I had already, and at the same time try to keep the track width as narrow as possible to stay within the working width of most of my implements. After a bit of trial and error, and with the help of a few washers, I got down to an outer width of 47 cm (18 ½’’) for the smaller inner wheels. The wheels are so close to the tractor, that on the right-hand side the tire is just clear of the gear quadrant. Then I used 1 of the factory 6 cm (2 ⅓’’) axle extensions, and again a few spacers, to mount the 23’’ wheels as close to the 20’’ ones as possible. The tires are really squeezed together, giving an outer track width of 78.5 cm (31’’).

This is how my setup looks with the Zanon ZRF 100 cm (40’’) drum mower attached:


Best regards

   / Berta flail mower #84  
That's really amazing Jens that you were able to get everything as narrow as 31". With my dual set the width I have is 34". And I'm using 2 sets of 5x10x20 tires. I intentionally left 1" space between the tires so that I could mount chains on both sets if I wanted to. I did the whole dual setup because I wanted to pull my disk harrow in the muddy spring and fall when I would sometimes get stuck in the mud. That's the time of year that I need to disk down the garden.

But in retrospect I wish I had tried to keep things a little narrower. I do a little bit of mowing on a very steep slope around a pond. I use a 30" sickle bar mower and it would be nice to have a little wider width and traction of the duals for stability. I can only guess that you mounted your hubs (The smaller wheel part that bolts to the tractor axle) on one of the inside surfaces where they bolt up on the smaller wheels. I didn't understand that you could do that at the time I made my setup.

Using the outer mounting surfaces to mount on the hub, my options for the width of the single wheels was either 22" or 24 1/2". I'll have to take a look at that. But I'm quite amazed that you were able to queeze it down to 18 1/2".
   / Berta flail mower
  • Thread Starter
Hi again Nibbana ;)

A narrow track width was my top priority when I got my 6.5x12x23’’ wheels 10 years ago. First of all to stay within the working width of most of my implements, secondly to enable me to park the tractor next to my car in the garage. When working with the Berta, I have a little more than an inch to spare on either side, witch is close to ideal I think.

I don’t recall which implements you have beside the disk harrow, but with your 5x10x20’’ wheels, you might be able to get very close to 30’’ outer width, to fit your sickle bar mower - if you try a little harder :ROFLMAO:

I don’t recall in detail anymore exactly how I mounted the wheels, but you are probably right that I did use the inner mounts. I remember that it was quite a puzzle, but for my purpose it has worked well.

Do you need a narrower track width than 34’’ for other implements than the sickle bar mower? I would think that for your disk harrow and other implements 34’’ should be no problem? The fact that you are able to put snow chains on your duals also is a great bonus I guess, perhaps also when working in muddy conditions?

Best regards

   / Berta flail mower #86  
Thanks Jens,

Yes. I was specifically thinking about the chains for soil working. I could easily fit the duals behind my plow but I don't think it would be any advantage over singles with the chains because the ground is frozen solid for snow moving and floatation isn't an issue.

Sorry, I do remember seeing your setup a while back but forgot about that. (Getting old.) I originally thought that there were four different orientations that the wheels could be mounted. And I even thought that the hubs would fit over the brake drums for more orientations. Which they don't. Then when I took the wheels off to measure for my wheel extensions, it looked to me like the radius of the bend in part of the wheel would prevent them from being mounted on the inside. I didn't actually take the time to take them apart and try to see if they would fit. I wasn't too worried about it because I was setting it up for my disk which is plenty wide. Now I see that I was wrong and they can be mounted in four different orientations. And I even think I might have read that on the BCS or Earth Tools website, but it might have been here.

Anyway, now I think you are right and I may be able to get it down to 30". I'm going to look at that the next time I have them off. I have areas that are extremely rough and rocky that I would like to mow with the sickle bar and duals would help. I also have the 26" tiller and bush hog, and 28" snow blower. I'm sure I won't be able to get duals down that narrow though. Not sure what would work for the rotary plow. For all the other non powered attachments I made the width doesn't so much matter. And floatation would probably benefit but not a big deal. It's just that we have a lot of moisture in the soil in New England and it gets muddy. In the garden, it gets deep.

I just ordered the BCS spring tine cultivator. For that I'm going to want as narrow as possible wheel width. I hope it works. I ran into a bunch of unexpected projects last year and the weeds got ahead of me.

   / Berta flail mower
  • Thread Starter
Hi again Nibbana 😉

As I removed the wheels on my tractor recently, I took a few photos to help explain how I made my dual wheel setup.

You are absolutely right that there are 4 different ways to mount the wheels - at least that is the case for the 5x10x20’’ and 6.5x12x23’’ that we have. There are 2 sets of brackets/tabs on the outer rim, and the inner hub can be flipped and positioned in 2 different ways on either set of brackets. This is my setup, where the 23’’ wheel to the right will be flipped and fastened to the wheel extension on the 20’’ wheel:


Just for the record - one can fit the hub over the brake drum as shown below. Whether that will be advantageous or not, I don’t know. I have had no problem getting the inner wheels very close to the tractor, with the hubs facing outwards:


As previously said, my priority was to keep the track width as narrow as possible, and the limiting factor on the inside towards the tractor is the gear quadrant, as seen below:


I made a 3 mm (⅛’’) gap between the 5x10x20’’ tire and the gear quadrant to be on the safe side.

The next photo shows the 20'' wheel from the side facing the tractor. Here one can also see the only real drawback of this setup, with the valve stem facing inwards:


The next photo shows the inner wheel mounted on the tractor, with a 6 cm (2 ⅜’’) wheel extension:


The last photo is a close-up of the 23’’ wheel with 2 washers on each bolt for the fine adjustment:


This setup has worked very well for me for more than 10 years now, making the tractor very stable on moderate slopes, and still be within the working width of most of my implements. Especially when working with the 85 cm (34’’) Berta flail mower, the combined tractor-mower setup works very well.

Best regards

   / Berta flail mower #88  
Good post Jens.

I could have sworn the hubs did not fit over the drums. I remember checking that. But your pictures don't lie and I've been wrong before. I agree though that in that position it would make the wheels too close and probably contact the controls.

I fooled around with this before I put my weights and chains on for the winter. With my wheel extensions I think I was able to get the width down to 31" maybe? Just a little wider than the sickle bar. Seemed like that would be okay for the sickle bar. But really not for a 28" bush hog or snow blower. So I decided the duals were going to be of limited use for me not wanting to continually change wheels. I'd just use them for the disk. Which is really what I need them for in the first place.

Now that you say the hubs fit over the drums I'll have another look in the spring. Again, I suspect the limiting factor is going to be the wheels contacting the controls; exactly what you're running into. It looks like the extensions sold in the US are 2 1/4. Yours are 2 3/8. So maybe some things are a little different between the 739 and 740.

   / Berta flail mower
  • Thread Starter
Hi again Nibbana ;)

I am glad if my photos were useful to you and perhaps other members too, as we are probably not the only ones trying to make duals work with different implements.

I would be very surprised if BCS would go to all the trouble of producing and selling different axle extensions for different tractor models or markets. The differences are probably caused in the conversion from metric to imperial units, I think.

Most 2-wheel tractors, and probably also most implements, are produced in Europe or Asia, and therefore in metric units. When converting to imperial units, a „round“ metric measure rarely converts into an equally round imperial one, as the conversion factors are rather odd. This probably makes it difficult for an importer like BCS America for instance, to find a proper value for many of their products.

One example could be the smallest axle extensions, which are 6 cm each, as can be seen on the BCS company website:

Wheel spacers - Bcs

When these extensions are shown on the BCS America website, they are 2.25’’ each:

Wheel Extensions - BCS America

This is a nice round number, but it is 4.75% less than the more precise 2.36’’.

Another example could be the PTO extension, which is 8 cm according to BCS Italy:

PTO extension - Bcs

On the BCS America website it’s 3’’:

PTO Extension - BCS America

Which again is 4.75% less than the more precise 3.15’’.

I fully understand that BCS America and others are preferring rounder numbers when converting to imperial units, one just has to be aware that this conversion is not always that precise.

As I have spent all 65 years of my life in the metric world, I’m of course more familiar with these units than the imperial ones. I noticed that you use the fractional version 2 ¼’’ and not the decimal version like BCS America does. Is there a reason for that, or is it simply personal preference?

Best regards

   / Berta flail mower #90  
That's interesting Jens. I'm sure you're right that they aren't producing two different sets of products for different markets. The only things I made that required accurate measurements of the BCS equipment were a blank male quick hitch and the wheel accessories.

It's really impossible for me to say what the manufacturers wheel bolt circle is because of the tolerances and difficulty in measuring the equipment accurately. I can say that the dimension I used was accurate enough to get the results I needed. Whatever it is, I think we agree that it's not a nice round number, metric or imperial. As I said before, I can only think the odd size wheel bolt circle diameter is just to prevent any other manufacturers wheels from easily mounting on a BCS tractor ensuring BCS's monopoly on their very expensive wheels.

I didn't attempt to convert my measurements of the quick hitch into metric units because all my machinery is imperial. That would be interesting to do but I'm sure my sketches are long gone. IIRC, the critical diameters on that part were not imperial fractions. The next time I get a chance I will make a few measurements and convert to metric. My guess is they will be nice round numbers.

I'm equally comfortable with fractions or decimals. When I make something that has to be reasonably accurate, of course I work in decimals. Otherwise I generally think in terms of fractions because it makes things easy to visualize for the simple mind.