# AMD FB1-4001 motor failure



## TheSGC (Nov 15, 2007)

Did you break in the brushes before driving it? I have the same motor, and its 14 years old and has over 10,000 miles on it and driving fine. I break in the brushed on 12 volts for about 2-3 hours when I first installed it, and I plan on doing the same thing once it goes into my new EV.

Was your timing advanced in the correct direction?


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## sbjohnston (Jul 15, 2011)

Thank you for the response. Break-in? - I ran the motor for two hours on a 12 volt battery and charger combination. Timing advanced? - The specsheet that came with the motor said it was ready for use in either direction with no adjustment. When the dealer asked the manufacturer about this point he was told the motor was to be used as set-up from the factory no matter what the rotational direction.

Steve


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## dladd (Jun 1, 2011)

sbjohnston said:


> Thank you for the response. Break-in? - I ran the motor for two hours on a 12 volt battery and charger combination. Timing advanced? - The specsheet that came with the motor said it was ready for use in either direction with no adjustment. When the dealer asked the manufacturer about this point he was told the motor was to be used as set-up from the factory no matter what the rotational direction.
> 
> Steve


complete motor noob here, but this doesn't sound right. At 144v, shouldn't the motor timing be advanced?


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## sbjohnston (Jul 15, 2011)

Thank you for your response. The motor was shipped to me in a crate from the dealer and I installed it on the vehicle. No one else touched it. I never had the headband off before the failure but I looked through the vent holes and saw that all the brushes were in the same position on the commutator. So all eight were originally down and operating. 

I disassembled the front of the motor and removed the brushes and holders. I can now see that the front four brushes have wear marks on their leading edges that are the same shape as the protruding piece of insulation. So clearly they were indeed down on the commutator - how else could they get that shape worn into them? I know it sounds surprising but the must have jumped up - they were down under the springs when I installed the motor, and then after it failed I found them up with the springs pressing on their sides. 

Steve


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## sbjohnston (Jul 15, 2011)

Let me clarify regarding the motor timing: I did not advance the timing - the motor already came that way. 

I have not made any change in the position of the brushes relative to the rest of the motor - it is in the same state as when it arrived and I installed it. I ordered the motor for electric vehicle use at this voltage. The information that came with the motor says it is "designed to operate in CCW rotation for forward vehicle motion." I wired it per the drawing for CCW rotation and that is what I got.

As shipped from the manufacturer the brushes are already in an advanced timing position. They are off the line of the pole piece bolts, shifted in the anti-rotation direction. 

Steve


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## sbjohnston (Jul 15, 2011)

I do not have photos of the brushes in the up position because I put them back down right away to test the motor on 12v. I didn't imagine such a basic observation would be disbelieved.

When I installed the motor I saw thru the vents all eight brushes in the down position. After the failure I removed the headband and found the front ones in the up position. That's the facts of the situation. 

Steve


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## Tesseract (Sep 27, 2008)

sbjohnston said:


> ...When I installed the motor I saw thru the vents all eight brushes in the down position. After the failure I removed the headband and found the front ones in the up position. That's the facts of the situation.
> 
> Steve


If thems the facts of the situation then you over-heated the motor and/or over-sped it. A comm bar lifted up and whacked the brushes so hard they were flung up into the servicing position. This isn't an installation failure, it's an operational failure. Do you often drive around in the higher gears so that motor RPM is relatively low?


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## Weisheimer (May 11, 2009)

It looks like the over-speed happened first. It isn't difficult to over-speed an unloaded motor.

The burning happened after the over-speed as shown by clean commutator under the lifted brush positions.

If it were mine, I'd see what a new armature and brush plate assembly with brushes would cost.

If you pull the motor and take it apart, you'll likely find that the commutator is no longer round.
Those strange bits you pointed out are mica insulation that lives between the commutator segments.
Did you find a some stuff that looked like "fish scale" in the motor vent area?
That would have been more of the mica that was thrown out from between the commutator segments.

You aren't the first to over-speed an armature...

Some of the newer controllers, such as the Soliton Jr can limit rpm's if mated with a sensor.


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## Tesseract (Sep 27, 2008)

gottdi said:


> No but the first I have ever heard of the 4 front brushes being flung into the service position. Hard to believe that one....


Not so hard to believe... Just the front end of the comm bar could have lifted. Of course I'm just speculating here - not unlike yourself - but in any case why would the OP remark on the brushes being in the service position if he had put them there himself??? That makes no sense.


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## Salty9 (Jul 13, 2009)

Does one of the com bars have a "loose tooth wiggle"?


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## dladd (Jun 1, 2011)

i could see this mode of failure. Something caused that mica stuff to rise up from between the comm bars. Overspeed? perhaps it was like that from the manufacturer? 

Once that piece is sticking up, it kicked the front 4 brushes up. The others are now doing twice the work, and eventually overheat.

Your setup doesn't sound unique, a 9" motor in an S-10 with transmission and Curtis 1231 is probably about the most common conversion out there, right? Certainly not a case of poor component choice.

Is there any chance you ever overspeeded the motor? Ever try pulling out of the garage thinking you were in reverse, but were really in neutral? (I've done that a few times...). An unloaded motor spins up REAL quickly.

Isn't it at least 'possible' that whatever is sticking up between the comm bars was there from the beginning, and it's been running on 4 brushes till now?


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## sbjohnston (Jul 15, 2011)

Here's a photo illustrating the positions I found the brushes in after the motor failure.

http://www.flickr.com/photos/[email protected]/7158276530/in/set-72157627254806189

 
Steve


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## GerhardRP (Nov 17, 2009)

sbjohnston said:


> Here's a photo illustrating the positions I found the brushes in after the motor failure.
> 
> http://www.flickr.com/photos/[email protected]/7158276530/in/set-72157627254806189
> 
> ...


Do you have pictures of the working surfaces of the brushes and the comm surfaces?
Gerhard


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## sbjohnston (Jul 15, 2011)

I have never subjected the motor to an overspeed condition, nor have I applied power with the shaft held fixed. My safety interlocks help prevent the latter situation. Details of my calculation of the RPM of the motor at the time of the failure is in my original post - it was 3320 rpm as I recall. 

The edges of the front brushes are not knocked off entirely - they are carved out in rough correspondence to the shape of the mica protruding from the commutator. 

I detect very little variation in height from one commutator bar to another. I don't have a precision measuring device but the bars feel the same height each to its neighbors. 

This motor comes set up with the brushes mounted offset from the line of the pole piece bolts in the anti-rotational direction. Thus I did not need to advance the timing - the motor was meant for electric vehicle use at this voltage and was supposed to be ready to go for this application.

I'm going to clean up the commutator and install a new brush-holder, springs, and brushes, and then first see how it turns by hand, watching the brushes ride and listening.

Steve


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## electro wrks (Mar 5, 2012)

I wonder if the brush holder came apart in your bottom brush position, causing part of its metal frame to contact the connection between the com bars and the arm winding(s). Was it touching when you first looked at it? If this was the case, it would cause all kinds of hell to break loose, arcing and overheating-wise.


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## sbjohnston (Jul 15, 2011)

Interesting thought, "electro-wrks" - I can't say it had touched but it was somewhat deformed. 

gottdi wrote:

>With that mica bit protruding you should not just run the motor. 
Huh? Who would do that? I trimmed it away with a razor. 

>When pushing the brush from beneath, you can't push it out like 
>you can pull it out. The spring pressure and position won't allow that. 

Thanks for the video demo. The dimensions of the holder, brushes, and springs are different in my motor. 
You mentioned the small bit of insulation being too small to kick the brushes up. The insulation is only 
protruding a small bit after the failure. I feel confident that it was a big "flap" when it started, and 
after the passes of the brushes it was be worn down to the nub we see now. 

The worn out areas on the front brushes are larger, but the same shape as the protruding insulation, 
further supporting the idea that the protrusion was larger at first.

Steve


Steve


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## sbjohnston (Jul 15, 2011)

I really appreciate everyone's thoughts on this problem. I am not comfortable saying there is "no chance" of one theory or another - in my years I've learned to never say never! Surprise lurks around every corner. But I do play the odds and appreciate your appraisals of the situation.

I cleaned up the commutator and installed the new brush holder, brushes, and springs and rotated the shaft by hand while watching the motion of the brushes. There is a very tiny "wave" to their motion in and out as the shaft goes around, so I think the overall shape of the commutator is not a perfect circle. I hear no clicking as the commutator runs under the brushes, so they seem to be riding smoothly over the bars.

There has been some talk of the need to "seat" the brushes before using them - is there anything special to be done when new brushes are installed?

Thanks...

Steve


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## sbjohnston (Jul 15, 2011)

I've added a photo of the front brushes to my collection. 

http://www.flickr.com/photos/[email protected]/sets/72157627254806189/

Steve


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## PStechPaul (May 1, 2012)

Very interesting thread. Sort of like "Forensic Files"! I've had to do some similar sleuthing when some of the test sets I've designed or modified have had problems in the field. There are usually several plausible solutions. And sometimes (as Sherlock Ohms has said), if you can eliminate all the usual causes, that which remains, however unlikely, is the culprit.

The only way I can see the brush being pushed out into that position would be if the mica piece had been longer, and flexible enough to initially bend and then extend far enough to push the brush out, and perhaps the leads of the brush could have pressed against the screen to keep the brush from popping out all the way. But then there probably would have been arc marks on the screen, since I assume the brushes have a high potential with respect to the frame.

ISTM, as gottdi asserts, that the motor must have failed previous to purchase because of the mica insulation hitting the brushes, and someone was in the process of servicing it. But then the cover was replaced and maybe the motor was put back in stock. Even if it was basically inspected and bench tested it probably would have seemed OK, and only after an extended period of normal use the remaining brushes were overloaded and eventually failed by overheating. The customer should not be expected to inspect a new motor except to check for obvious shipping damage and such.

I do recommend that the armature should be removed and the commutator with the loose mica insulation should be carefully inspected, perhaps with a new piece of mica forced in place and glued. It may be worthwhile to take it to a motor repair shop to have it done properly. If the commutator segments get loose and short out it could cause a catrastrophic failure.


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## sbjohnston (Jul 15, 2011)

An EV professional who must remain anonymous sent me a photo showing another motor that did the same amazing brush-jump trick. I've posted the picture on my Flickr site - it is the last photo in the set. Note the spring pressing against the side of the one brush.

http://www.flickr.com/photos/[email protected]/sets/72157627254806189/

Steve


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## sbjohnston (Jul 15, 2011)

What "BS" are you talking about? I long ago gave up any hope of the manufacturer providing me any help, so there is no economic incentive for me to exaggerate or misrepresent anything! 

A guy who sells motors for EVs sent me a picture of a motor that he saw that did the same thing as mine. I really appreciate his willingness to help me understand what happened, and I don't want to say who it is for fear of messing up his business. Simple as that - I urge you to reconsider your accusatory tone.

Steve


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## sbjohnston (Jul 15, 2011)

Now I see you are using a comic to say that my information is fictional. Nice. I'm done listening to your insults.

Steve


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## PStechPaul (May 1, 2012)

There does not even seem to be any sign of damage on the commutator where the brush is lifted up. Were there any clues as to what could have caused this? I think it could be possible if a piece of the mica insulation came loose and bent as it encountered the brush, and then extended far enough to push it out as shown. And I think also the travel would need to be limited, perhaps by the brush wires pressing against the cover screen. It would also be helpful to show the condition of the brushes, and a view of the entire commutator to see if there are any open spaces where insulation might have come out. If so, it should be possible to duplicate the phenomenon by inserting a similar piece of material and rotating the shaft by hand.

Problems like this are a good reason to use AC induction motors.


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## Tesseract (Sep 27, 2008)

gottdi said:


> Insults? What about the brushes and NO proof. I even went out of my way to do some testing and videoing and you still maintain this. PROOVE IT DID HAPPEN.


Good grief, Pete... Lay off the dude, will you? Why are you so bent out of shape? As far as I can tell the OP is just trying to figure out why his motor failed so I don't really see why you have to go all District Attorney on him...

Your video doesn't prove anything except that in this one particular case you couldn't duplicate his results. Don't confuse a single data point in support of your supposition with absolute proof of it.


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## Tesseract (Sep 27, 2008)

gottdi said:


> Well at lest I have a VIDEO that could not duplicate the issue.


Filming a video does not a automagically create more data points.



gottdi said:


> My data points are better including that until he said it happened no one ever ever ever mentioned that a brush popped out of socket and came to rest with the spring holding it in service position. Let alone all four on one side.


Do not confuse "unlikely" with "impossible". If a piece of the mica insulation between the commutator segments worked itself loose it could thwack the brushes up as the motor spun. Is this likely? No. Is it impossible to conceive of it happening? Also no.



gottdi said:


> Fine, I'll back off and let all the new folks think it is an issue that can happen with no proof to the issue and you can be happy to know that information like this is being spread around.


You do love unintended irony, don't you? 

My position is and has been that we should keep an open mind about the cause of this strange failure and not be so quick to dismiss possible causes, even if they seem bloody unlikely. You, on the other hand, have basically been trying to prove the OP a liar and/or the perpetrator of a hoax. So who is spreading FUD?



gottdi said:


> Ignorance is bliss and very expensive. You really want the new folks to be ignorant or do you want them knowledgeable. *Well I guess ignorant will put more money in the pocket.*


Says the guy who has written 138 posts recommending Synkromotive.


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## SandRailEV (May 11, 2012)

I can see this happening... When things move very fast, parts can move in unexpected directions... The energy of the collision must be disipated somewhere and in this scenario it certainly seems plausible to me that one could end up with the result that was shown by the op...


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## SandRailEV (May 11, 2012)

Whatever you say master....


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## EVfun (Mar 14, 2010)

Pete, your posts are dominating this thread recently. Please take a deep breath and relax. You seem far to worked up over someone else's 9 inch motor failure. I don't want you to have an aneurysm. Peace.


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## SandRailEV (May 11, 2012)

gottdi said:


> Ignorance is bliss and expensive. You choose.


 
You are entitled to your opinion and I am entitled to mine. Frankly, after reading your responses in this thread, to me you offer no evidence to support your claim. 

Firstly, the edge of the brush isn't riding at exactly 90º to the commutator, there is a slight angle there due to the commutator being round. Secondly, the brush edge isn't perfectly squared off, there will always be a radius on it, however small. So, if something on the commutator comes in contact with the brush, it can and will have a lifting effect, particularly at high speed. If the speed is high enough, it is possible to transfer enough energy to lift the brush all the way up until the spring no is no longer on top of the brush. How much speed?? I don't know, but I see it as very possible.

Now, on your theory that a moving object striking another can't move said object in a 90º angle to the direction of travel; If I shoot a gun at a concrete wall, not only will debris come out of the collision at 90º, it will also come out at much smaller angles also, even against the direction of travel. So, your theory is bunk.

Again, I am entitled to my opinion, and this is my opinion. Don't bother to answer this post as I will no longer argue with you.


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## poprock (Apr 29, 2010)

Hi, as a novice I am intrigued by this discussion. If there have been two incidents of this type then it is worth solving. If the mica? did come loose from the armature then the manufacturer should be concerned enough to carry out tests to attempt duplication of this fault. As a novice imho overheat then overspeed while running hot may have caused this. Lets get consensus on this


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## JRP3 (Mar 7, 2008)

Pete often sees conspiracies where there are none, and often forms an opinion, states it as irrefutable fact, and comes off as an angry close minded nut. Of course he never sees it that way. It's part of his charm


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## DIYguy (Sep 18, 2008)

Interesting thread. Some brushes were found in the service position. Brush leads, springs burned off, damage to brush edges. So, you look to see what could cause it and find insulation lifted. All adds up pretty clearly. The resulting heat damage on the brush rigging makes sense as a result of the damage.

In my little brain, the focus should not be on what caused the brushes to jump and resulting heat damage. As Tesseract indicated, the insulation/com failure is usually related to overspeed. I would focus on testing your rev limiter in every way possible. Check the connections, look at the signal on a scope, maybe have some discussion on this part of it. Look at the controller rev limiting capability etc. If all of this leads no-where, then it makes some sense that there may have been a manufacturing defect in the motor/comm. Will you get some resolution/warranty? Unlikely. But one thing is for sure, . . either way, if you plan to drive this vehicle again, you need to be sure the rev limiter is working correctly. 

Finally, regarding the motor as it is. I don't think you should consider using it. You need to get it rebuilt with a new/remanufactured armature and repaired brush rigging. An out of round comm is an indication of damage and it will not handle any serious rpm for any length of time. You'll just be pulling it out again soon. 

(Pete, please don't bother to pick my comments apart, we already know your thoughts, thanks.)


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## ruckus (Apr 15, 2009)

Wow, a good example of an ev discussion going awry. I think folks need to be mindful of how it is easy to come off as brusque/jerky/accusatory in print where voice inflection cannot be heard. Politeness goes a long way.

I too am having brush troubles of a different sort (arcing). Yes, these motors have been in forklifts for a long time, but forklifts use VERY low gears, easing the strain on the motor. EV use is COMPLETELY different as people are not using 1st gear. Instead they start out in 3rd putting great strain on the motor. This thread shows one of many failures that are happening with brushed motors of all brands. This is with relatively low numbers in service. Imagine 2 million of these out there. That is a real data set. Industry is gentle compared to the consumer.

The solution has been to use bigger and bigger motors. But that is not a true solution. Just because it can move a forklift at 3mph does not mean it is suitable tech for 500,000 miles of hard use. 

Brushed motors, RIP. and just when the controllers are getting good too..


Ok. slaughter me now...


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## SandRailEV (May 11, 2012)

ruckus said:


> Wow, a good example of an ev discussion going awry. I think folks need to be mindful of how it is easy to come off as brusque/jerky/accusatory in print where voice inflection cannot be heard. Politeness goes a long way.
> 
> I too am having brush troubles of a different sort (arcing). Yes, these motors have been in forklifts for a long time, but forklifts use VERY low gears, easing the strain on the motor. EV use is COMPLETELY different as people are not using 1st gear. Instead they start out in 3rd putting great strain on the motor. This thread shows one of many failures that are happening with brushed motors of all brands. This is will relatively low numbers in service. Imagine 2 million of these out there. That is a real data set.
> 
> ...


 
No slaughtering here, I have to agree with you...


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## JRP3 (Mar 7, 2008)

Let's not forget that people have been overpowering forklift motors successfully for at least 20 years.


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## JRP3 (Mar 7, 2008)

gottdi said:


> No conspiracy here. Hardly closed minded as you assume. I'd bet I am the least of the closed minded on this forum. Angry is in your head.


As I said, you never see it that way, even though multiple people have made the same comments about your posts for years. Have you ever wondered why so many people think you are angry when you post?


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## JRP3 (Mar 7, 2008)

Still missing the point, as usual. No one is angry at you, YOU come off as angry to everyone else. You might want to ask yourself why.


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## PStechPaul (May 1, 2012)

I should probably stay out of this, but I still think there may be a mechanism whereby this might have happened, and if I had a similar junk motor I could rig up a test to determine if it is even possible. I agree that it is highly unlikely and the photos are insufficient evidence. The video I saw seemed to be a somewhat clumsy attempt to discredit any alternate explanation. A sincere attempt to reproduce the brush condition, by various mechanisms, would go far to determine what might or might not have happened.


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## ruckus (Apr 15, 2009)

Ok, so at 5000 rpm a piece of "foil" is travelling at ? mph (determined by comm radius) and thus has the force of ?. The higher the speed, the more force it can strike with. Everybody is assuming overspeed, but it could be just simple failure.

My ADC motor had a chunk of putty fall out. That builds confidence in the quality construction. 

From the video we can clearly see that at a fairly consistent force the brush "pops" out.


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## ruckus (Apr 15, 2009)

gottdi said:


> I am doing the parallel test to see if I can get it to pop out of the socket. I can get sufficient force. If it won't come out with the force applied in parallel there will be no chance with the force applied at 90 degrees.


Please don't miss that the leads which bring power to the brush counteract the "tends to pull toward the spring" force. In fact a brush pushed from below would raise up and then "swing" towards the leads as they became taught. In your video you had the leads undone which did not show this natural action.

Instead of / in addition to hitting it with a hammer, you could measure the force with a pull scale. The needed mass and speed of the foil could then be determined by formula. The edge of the brushes are chipped away like they were struck with great force. (or is that the other set which were damaged by over-current).

Forget the 90 deg thing. If you hit a curb going 60 it still causes you to catch air despite it being at 90 degrees to your momentum.

Finally, your approach is a bit incorrect as you CANNOT scientifically disprove a theory. It is ONLY possible to create data which supports a competing theory. I think that is why folks are somewhat offended. It is absolutely and totally IMPOSSIBLE for you to prove-without-a-shadow-of-a-doubt that this could "never" happen on ADC motors. (especially by testing a Kostov).

Cheers


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## Duncan (Dec 8, 2008)

_Finally, your approach is a bit incorrect as you CANNOT scientifically disprove a theory. It is ONLY possible to create data which supports a competing theory. I think that is why folks are somewhat offended. It is absolutely and totally IMPOSSIBLE for you to prove-without-a-shadow-of-a-doubt that this could "never" happen on ADC motors. (especially by testing a Kostov).

_Hi Ruckus

Pete has been "testing a possible mechanism"so the disproving a theory is null


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## ruckus (Apr 15, 2009)

No, he is trying to show it could NEVER happen. That is very different from testing possible mechanisms and is not science. The hammer test is the beginnings of a scientific inquiry.

Scientists should never go into a test assuming they already "know" the result. At best you are testing a hypothesis under controlled conditions. 

If I wanted to "prove" EV's are junk I could find a poorly made example, drive it till it pukes and then claim I was right all along and this test "proves" they are junk. But did I "prove" anything? or was it mental masturbation? 

A proper analysis of this motor failure would be to form a double hypothesis.

1. The motor suffered comm construction failure and the brushes were popped out by either the out-of-round comm or bits of foil at speed.

2. The motor suffered comm construction failure and the brushes were lifted by human hand. Then forgotten about or intentionally sold as fraud.

Either way the comm still suffered construction failure and should be the main part of the investigation.


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## DIYguy (Sep 18, 2008)

ruckus said:


> Either way the comm still suffered construction failure and should be the main part of the investigation.


Exactly, important point. 

. . . and since the brushes were damaged. . .it kinda makes sense what happened. Even if someone pulled the brushes (unlikely) that wouldn't cause the comm failure.


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## SandRailEV (May 11, 2012)

Ok, here we are again.

I submit that a hammer test won't prove anything because for the brush to have popped out due to a force from underneath it, it would have had to transfer enough energy at high speed so that the brush and spring gained enough inertia to continue up the brush holder. I can see this happenning. I don't believe it would have made any loud noises either because the brushes are contained within the motor and the driver is far away from the source with other noises surrounding him. 

Further, the insulator might not have been made of mica either..

"Each conducting segment on the armature of the commutator is insulated from adjacent segments. Initially when the technology was first developed, mica was used as an insulator between commutation segments. Later materials research into polymers brought the development of plastic spacers which are more durable and less prone to cracking, and have a higher and more uniform breakdown voltage than mica."
Source: https://en.wikipedia.org/wiki/Commutator_(electric)

So, if a polymer was used, it easily could have bent over and acted like a wedge at high speed causing the brush to bounce at higher and higher speed until the spring finally caught it. Once caught by the spring, all the current would have been transfered to the other brush and overloaded it.

So, only a theory but one that COULD be duplicated with relative ease if a donor motor was available... 

As for why the insulator came loose, I suppose either manufacturing defect or the motor was way over-speeded at some point, or way overheated at some point...

Just an opinion...


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