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In my lawmower's motor plastic fan/ventilator on rotor has broken to few pieces 1 2

There are 2 small springs in fan's slots.

What is the purpose of these springs?

Are there any standards for such components?

Edit: This is how it looks like in working motor: enter image description here

And in my disassembling lawnmower some years ago: enter image description here

Edit 2: Today I've got some other broken motor (burnt winding) but with fully operational fan so I was able to check it how it's working.

The simplest solutions are the best - this springs work as brake when motor is no longer supplied

Here are some photos how fan is mounted on the shaft and where are springs (bottom view): side view - cross section

bottom view

Springs are mounted inside fan and tightly touch fragment of the plastic on the top of stator. When motor starts spinning, centrifugal force "pushes" springs outside of stator so there is no sliding. When motor losts supply, rotor spins slower and springs start sliding of the plastic which stops rotor much faster than without it. Thanks to that we don't need to wait eternity to open basket and throw grass.

Due to friction between metal and plastic, it heats up and melts plastic on stator. I saw many small melted pieces around place where springs slide, so maybe my fan was destroyed by some bigger fragments of such melted pieces... I think manufacturer should put of the stator some rubber or some additional material between plastic and springs.

Anyway the topic can be closed. If you would have some more comments, feel free to write :)

voldi
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  • Out of the fan after it's broken. Normally there are inside small slot visible in the picture. Also you can check how it looks like in working motor: https://kosiarkijura.pl/images/Czesci_do_kosiarek/silnik%20Gardena%201800%2042%20b.jpg – voldi Sep 04 '22 at 18:14
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    that picture belongs in your question above ... it certainly does not belong in a comment – jsotola Sep 04 '22 at 18:20
  • there is probably another component that is missing – jsotola Sep 04 '22 at 18:22
  • I've just showed you with the link in the comment above how it should look like in normal condition. I cannot upload my pictures in the comment so I will edit original post. – voldi Sep 05 '22 at 06:11
  • @voldi comments are not for pictures or further information so adding to the question is the correct behavior. Also, why not just buy the fan from the manufacturer? – Solar Mike Sep 05 '22 at 06:26
  • If it would be that easy, I would not write question here ;) Googling numbers stamped on the fan gives no results. The "smallest" spare part indexed and sold by manufacturer (Gardena company produced by Huqvarna) is whole motor together with belt transmission etc. Price for that in over half price for new lawnmower. I'm not experienced with looking for such "subcomponents", nor familiar with rotor's fans. If you're more experienced with such things, you can try to find it. Motor spare part number is 5037-00.907.00. – voldi Sep 05 '22 at 06:47
  • This is a good question, but (for me at least) the pictures & verbiage are not showing the location of the spring, its shape or the components to which the spring(s) are connected. @Vladimir seems to "get it" from previous experience, but my point is "Better answers may come from a clearer question". – Seamus Sep 13 '22 at 12:37
  • I edited original post, because other motor arrived and I was able to study more carefully how everything works when it's not shaterred to pieces. – voldi Sep 21 '22 at 06:15

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Seems that these springs abut to some part that sits on the motor shaft firmly, closer to motor. Then their purpose is to press fan wheel to the pulley which drives the belt while fan wheel fits on the shaft loosely. This works as friction clutch to prevent what had happened.

I experienced such hi-speed fan explosion in cheap wood router, and it was necessary to use particularly that tool. At first time we glued its parts and tightened it with aluminium hoops. After repeated breakage (that time it was "human factor") we made new wheel from aluminium on CNC milling machine, with much simpler geometry of course.

At first sight, it is possible to use one spring and put it on the motor shaft. This will allow to make simple fan wheel. It is hard to see, but seems it is made from polyacetal, it is hard to glue.

Vladimir
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