# Repair a drum mower blade disc drive gear



## Norppu (Jul 3, 2022)

My neighbour has a  drum mower with two broken blade disc drive gears.
The shaft holding the rotating blade plate had a fatigue crack that ended up breaking the shaft into two pieces.
I do a simple repair for this component by tapping a M14/1 thread to the gear and then making a stud bolt to replace the broken off part.







*In this video I am using*:
- Weiler Matador SV (1972) Lathe
- Schaublin SV-51 (1955) Milling machine


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## markba633csi (Jul 4, 2022)

Your neighbor should buy you a lunch for that 
or at least an espresso


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## Norppu (Jul 4, 2022)

markba633csi said:


> Your neighbor should buy you a lunch for that
> or at least an espresso


Well, he bought me 7 bottles of Cronbacher Weissbier (wheat beer).


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## SLK001 (Jul 4, 2022)

What is a drum mower?


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## Norppu (Jul 4, 2022)

SLK001 said:


> What is a drum mower?


It is a machine to cut long grass in a field. It has multiple spinning discs that have cutting blades attached at the rim. These discs spin relatively fast, 1000 RPM and even more.
The thing has the same operating principle as a household lawn mower. It is just bigger and faster and has (in this case) 6 rotating discs instead of just 1 or 2.


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## wachuko (Jul 4, 2022)

Norppu said:


> It is a machine to cut long grass in a field. It has multiple spinning discs that have cutting blades attached at the rim. These discs spin relatively fast, 1000 RPM and even more.
> The thing has the same operating principle as a household lawn mower. It is just bigger and faster and has (in this case) 6 rotating discs instead of just 1 or 2.





SLK001 said:


> What is a drum mower?



Like this?


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## Norppu (Jul 4, 2022)

wachuko said:


> Like this?


Yes, just like that.


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## twraska (Jul 4, 2022)

wachuko said:


> Like this?
> 
> 
> 
> ...


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## Firebrick43 (Jul 4, 2022)

wachuko said:


> View attachment 412561


The bottom one is NOT a drum mower, it is a disc mower, two different things


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## Norppu (Jul 4, 2022)

Firebrick43 said:


> The bottom one is NOT a drum mower, it is a disc mower, two different things


So it seems. I have not seen the actual machine this gear was sitting on and since I am not a farmer my knowledge over these machines is next to nothing. But, since it had 6 rotating discs, it is probably safe to assume it was indeed a disc mower. Anyway, something that is used to cut long grass and something one should not run into a big stone.


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## Firebrick43 (Jul 4, 2022)

Norppu said:


> So it seems. I have not seen the actual machine this gear was sitting on and since I am not a farmer my knowledge over these machines is next to nothing. But, since it had 6 rotating discs, it is probably safe to assume it was indeed a disc mower. Anyway, something that is used to cut long grass and something one should not run into a big stone.


If it had 6 spindles, definitely was a disc mower, or I should say I have never seen a 6 drum mower.  A disc mower drives the spindles from the bottom, drum mowers from the top.

All disc mowers use an oil bath gear driven spindles, the spindle gear and two idler gears set in each section case.  The cases are bolted together to get as many as needed.  So the first section case has to transmit all the power for the following ones and so forth.  They are heavy, expensive, and yes, don't do well with rocks.  Disc mowers lay the cut crop pretty flat unless its paired with a crimper roll, aka disc bine.

Drum mowers have some variation on how they are made.  Some use a 90 degree gearbox to drive a central drive shaft with bevel gears along the shaft that drive a bevel gear on each drum.  Some others use a 90 degree gearbox and then use belts to drive the drums. Either way, much simpler than a disc mower

Drum mowers tend to form a windrow between the drums as a pair turn opposite of each other.


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