Blown Puma gear - replaced

[kZs0lt]

Today I managed to blow one of the plastic planetary gears of my PUMA motor.

I've bought it second from UK a year ago, have served me great, has more then 2000km on it. It was overpowered from the beginning.
Most of the time I run it at 66v(18sLiM) 20a controller(70a phase), but 2 weeks ago was boosted to 30a. I think I have set it back to 20a, but I'm not that sure about it. This looks like the BMC v1, white plastic gears, so recommended @400w continuous, me using it at 1400w peak, and continuous for couple of minutes sometimes. Last week @ 1800w(30a, 58v-18s LiFePo4).

Today I have climbed a hill of about 2km, 8-10% @~25km/h, than wait for about 15min, then going down, I observed some noise from the wheel. I stopped and figured out it was coming from inside of motor and it was not present while pedaling and motor freewheeled. Went home pedaling and popped up the motor to have some very unpleasant surprise:



One of the planetary gears lost 2 teeth, and the teeth were chewed by the others.
At the moment I am looking for some replacement gears(posted to items wanted) and I will need some help to change them.

Is easier to change the whole gearset assembly with freewheel, or it's easier to change just the gears? I don't have pullers.
Should I get a metal gear or just get the composite ones? I would stick to 20a, but lower than that is just boring. I don't want it noisier if possible, and I think they should act as a fuse so don't want to blow something else with metal gears, if not absolutely necessary.

How can I change just the gears?
Only one of the gears has teeth missing, but I think the other 2 are a little affected by chewing the 2 broken teeth which got between them.

I think there was already a post with replacing planetary gears, I will try to find it.
Any help, or suggestion is appreciated.

Zsolt

 

[Mark_A_W]

I have done the same thing with my MAC Shanghai motor.


I tried the steel gear from MAC with my motor, and the soft steel gears wear very quickly, even when run in oil. The steel dust ends up in the magnets. Hardening the gears would help, I haven't tried this, as the steel gears are very noisy.

BMC have a Green composite gear, I'm not sure what material exactly, but no-one has stripped them, as far as I am aware.

If your gears have 54t, and an outer diameter of 56mm, then the BMC gears should fit. (They are module 1, 54 tooth, 20 degree pressure angle, 8.5mm wide gears, with a bearing with an 8mm diameter inner race.)

 

[full-throttle]

This is a common problem with plastic gears.

Your options are:
1) Get another set of plastic replacements, turn the current limit back to 20A and find out how lucky you are.
2) Get a set of composite BMC (green) and enjoy the extra power
3) Get MAC metal gear(s) - just do a search and get them hardened

It all depend on how much you want to spend

I also recommend talking to cell_man on this subject.

Edit: Mark, you beat me to it!

 

[John in CR]

Other than the low power Heinsmans with one metal gear, has anyone heard of a geared hub brand with no reports of peanut butter gears? It's beyond me that any electric motor manufacturer would let such products out of the door.

 

[Mark_A_W]

Well, I'd been putting 2000w through a motor rated for 500w.

I can't really complain.

 

[full-throttle]

Other than the low power Heinsmans with one metal gear, has anyone heard of a geared hub brand with no reports of peanut butter gears? It's beyond me that any electric motor manufacturer would let such products out of the door.

Yep, Bafang BPM.

I'm running mine (350W rated) @ 1,400Wpeak / 700W continuous. 4,000km and counting. Perhaps there are too few in the field to tell for sure though..

 

[Nogwin]

Same here, Bafang 80V, and average 450W/hr. Sometimes peak at 2KW like I did today.
I have around 5000 miles on the nylon gears, and still it runs fantastic - just keep it easy under accel...

Nog

 

[kZs0lt]

Thanks for your replies!

Yes Mark, they are 54t, approx 8.5mm wide and probably 56mm diameter. Don't know about the bearing, I couldn't take them apart.

Your options are:
1) Get another set of plastic replacements, turn the current limit back to 20A and find out how lucky you are.
2) Get a set of composite BMC (green) and enjoy the extra power
3) Get MAC metal gear(s) - just do a search and get them hardened

It all depend on how much you want to spend

I would like to try the green BMC composite gears, but I don't want to spend a fortune on gears, I had this motor bought second at a great price. So even one plastic gear is an option, but 3 composites would be nice if the price is reasonable.

Well, I'd been putting 2000w through a motor rated for 500w.
I can't really complain.

Neither I, this motor is rated 250w (!), and had seen in excess of 2000w. (30a with 18s LiM, 73.8v fresh off the charger, almost 70v under 30a load)

Currently I am stalled in getting out the gear.
I have a sieger (? or how do you call it) on the shaft, and a key also. there are 3 bolts on the freewheel as well, but taking them out doesn't make much sense.(?)

What should I do to be able to replace the gears? Can provide close-up photo from any angle if that helps.
Will talk to cell_man, any other offer is welcomed

 

[Mark_A_W]

On my motor there is a circlip on the axle, which holds the freewheel/clutch/gears assembly in place.


You remove the circlip, carefully clamp the freewheel disc in a vice, and tap the axle out with a screwdriver+hammer.


On your motor I don't know, but I don't think it's the screws on the freewheel. The whole assembly should come off.



Ilia at ebikes-sf.com can supply BMC gears, but he sells them complete with freewheel/clutches as an assembly, and I don't think the freewheel would fit your motor.

 

[kZs0lt]

Thanks Mark for such a quick response!

I post a picture of one of the gears that did not broke, but is slightly affected, so you can advice me to change it or not. Probably the broken teeth got in between, and slightly deformed some tooth.


Ok, I got it, need to remove the circlip as you call it, but it's still hard to move the assembly. Should I press the freewheel's disk (onto which the gears are mounted) against the brown magnet housing?

I also have a key beyond the circlip. Do I need to remove, or do something about it?


Thanks Mark for all of your help.

 

[Mark_A_W]

You will need to change all the gears.


Yes, remove the circlip, best done using circlip pliers, but you can do it with pointy-noise pliers if you are lucky.


Then the freewheel assembly should come off. It may be very tight, and you may need to clamp the freewheel "disc" in a vice, and tap the axle with a screwdriver+hammer.

Be CAREFUL not to loose the little metal key - it will fall out, so face it upwards when you put the motor in the vice.


From the looks of that photo, the BMC freewheel/gear assembly may fit. It's different, but it may fit.

 

[kZs0lt]

I think I am a little confused by the versions and differences between BMC, MAC, PUMA.

I've got it from UK and thought it was the motor marketed by Team Hybrid as a PUMA, possibly older version.

But on the cover says BMC, and 36v 250w on the sticker, so this could be a genuine BMC v1 after all. But the BMC's I saw on the net had slightly different side plates.

I have some old photos of it here, when I got it.

 

[cell_man]

I replied to the PM. Give me a few days to see what I can do for spares and I'll get back to you. The pics look a bit different from the lower powered Mac motors I have so I can't so for sure if your motor is a BMC or a Mac. The gears certainly look very similar but the assembly looks a bit different from what I have.

 

[kZs0lt]

Thanks for the message cell_man.

The gears are 54t, and from what I can see they are exactly as Mark mentioned, "8.5mm wide, 56mm diameter, 20 degree pressure angle, with a bearing with an 8mm diameter inner race." It is definitely 54t, but I will confirm the rest of the data when I manage to get them out. It looks like 8.5mm wide and somewhere close to 56mm in diameter.

It is labeled BMC, 250w motor. I will cross link the photos of the motor from my old thread for your convenience.


Drive side

Non drive side, has 6 bolts for disk brake, very wide placement.

Internals

Frewheel assembly

 

[kZs0lt]

I am having a hard time to get off the freewheel assembly.

I knocked the axle pretty hard but the freewheel assemblt won't come off. It comes out about 5mm, then it will stuck. Tried adapting a bearing puller, but couldn't pull hard enough with. Is there something preventing me to take it off? Are you sure I don't need to unsrew the 3 philip bolts on the assembly. I think it should disassemble the freewheel, and I don't need to bother with those, but something is stopping me to get the whole assembly off. The key is freely moving inside the keyway.

Zsolt

 

[kZs0lt]

I still couldn't get the freewheel assembly off the axle.

When the assembly is in it's place, the key moves about 5mm in and out in the groove.
When I pull the assembly out a couple millimeters, it moves less, and when pulling out the assembly, the key comes whith it out in the groove too. When the key comes to the end of the groove, I'm stuck.
Those 5mm comes easily even by hand, but past that, I was not able to pull out even with an adapted bearing puller.

Something is preventing me to get the freewheel assembly off. It seems that the groove is not through all the freewheel assembly, it may have a flange on the back(planetary gear side). I thought there should be a groove, but I just need to align it (upper part of the assembly rotates around the axle), but there seems to be no groove on the back side. It's not very clear because of the gears blocking the view, but I can see none, and rotating all around could not feel any point where the key would go backwards.

Notice that this freewheel is different from BMC v2 seen here and here, also differs from the one in the video.

Is it possible, that it could come down only the other direction after removing stator and rotor(magnet wheel)?
It does not make any sense. I may try to get a more professional puller, but I don't know if raw power is what we need here. It already bent my adapter like butter, where I used Fi 6mm pins bent as jaws. Made some visible scars on the freewheel assembly as well. I fear to put in more force.

Can anyone give some advice, does anyone have experience with this particular motor/assembly? What can I do, please help!
Wish knoxie would still be on the board...

Zsolt

EDIT: May provide additional pics.

 

[nicobie]

You've got to take off the c clip then using a 8" puller pull off the clutch/gear assembly.

 

[kZs0lt]

You've got to take off the c clip then using a 8" puller pull off the clutch/gear assembly.

I have removed the circlip, the photo was made prior that. Think I need to make some new photos.
I don't have the 3 jaw gear puller, but adapted a bearing puller. Tried to pull real hard, but it's stuck. Something won't let it come off the axle.
It takes the key with him, and when the key approaches the end of the groove, It won't come further.

 

[kZs0lt]

I could still not figure out a way to get this clutch off.

Ok, it's not easy for me to explain this.
When the freewheel/clutch assembly is in it's normal place, I can move the little metallic key back and forth for about 5 mm.
When I pull the assembly out a couple millimeters, it moves less, and when pulling out the assembly, the key comes whith it out in the groove too. When the key comes to the end of the groove, I'm stuck.
Till there it goes easily, now goes even by hand.


Note that one of the gears(upper one) is already unlocked, but can't get it out, not enough clearance.

It seems the assembly does not have the groove all the way through the clutch. From the backside I see only the flange of the bearing that is on the axle, it slips on the axle, but can't come past the key.
I thought there should be a groove, and I just need to align it (upper part of the assembly rotates around the axle), but there seems to be no groove on the back side. It's not very clear because of the gears blocking the view, but I can see none, and rotating all around while pushing the key backward could not feel any point where the key would escape backwards.



Notice that this freewheel is completely different from BMC v2 here, with clear groove/keyway:

It is probably more like Knoxie's motor here.

Is it possible, that it could come down only the other direction after removing stator and rotor(magnet wheel)?
That would not make much sense. I may try to get a more professional puller, but I don't know if raw power is what we need here. It already bent my adapter easily, something is preventing the clutch/freewheel assembly to come off. I fear to put in more force. It has to have some mechanical trick...

Can someone give advice?

 

[itselectric]

I could still not figure out a way to get this clutch off.
Can someone give advice?

kZs0lt:

What you have is not BMC v1, v2, v3. It is before v1. As a result, it may have some differ construction.

I am sure you have seen this video, which is for v1, Jerome is guy in the video, he is our mechanic, let me know if you want to talk to him, i can make the arrangement for you.
http://www.youtube.com/watch?v=Jg4zOmHTdW4

Or, the best person to talk is directly from BMC, here is the contact information:

http://bmcus.com/contactus.htm

But be aware that he may or may not want to talk to you depends how you start the conversation, he may send you back to the dealer where you get your motor from.

Good Luck!
Ken

 

[kZs0lt]

What you have is not BMC v1, v2, v3. It is before v1. As a result, it may have some differ construction.

I am sure you have seen this video, which is for v1, Jerome is guy in the video, he is our mechanic, let me know if you want to talk to him, i can make the arrangement for you.
http://www.youtube.com/watch?v=Jg4zOmHTdW4

Thanks for your tips, Ken!

OK, so this is not a BMC v1, thanks for pointing this out.
Yes I have seen the video with Jerome, nice hands-on video. It seems that on the video that was a different clutch.
Can you kindly ask him if he is familiar with this particular motor(have some outlook pics on the previous page), he may know what I need to do if he had once assembled one of these?

Or, the best person to talk is directly from BMC, here is the contact information:

http://bmcus.com/contactus.htm

But be aware that he may or may not want to talk to you depends how you start the conversation, he may send you back to the dealer where you get your motor from.

I acquired this motor in used condition a year ago from a forum member from UK.
Since it differs from BMC v1, v2, v3 it should be an older refined version marketed under the PUMA brand in UK, so I will try to ask for help from teamhybrid instead of BMC US, this motor may be coming from them. Maybe Mark Higgon from teamhybrid may offer some inside to this motor.

Thanks again for the advice,
Zsolt

 

[Burtie]

Does removing the 3 screws allow you to split the freewheel assembly and remove the key?

Burtie

 

[kZs0lt]

Does removing the 3 screws allow you to split the freewheel assembly and remove the key?

Burtie

No, unfortunately it won't, tried that...even if it worked that way, would make no sense to design it that way
I'm completely clueless what to do right now...

 

[cell_man]

I'm pretty sure you just need to get a gear puller on there to remove the clutch assembly. The keyway is probably jammed into the clutch key.

 

[Mark_A_W]

Yes, does the key "rock up" and jam as you move the freewheel up?


I've never seen this particular version of the motor, but it seems very strange to me that it won't come off.