HI so I have a 646se wheelchair with freewheel lever in front of the motor and serial number of the chair is S64A-052891
and serial of its motor are pn 118947 S/N004-3SM

When I contact sunrise medical for a set of 4 brushes they tell me it is item 112281 and 124 dol so 150 from local shop and that seems ridiculously expensive for 4 brushes. Most set I see on amazon are like 4 or more for 20 dollars.

Now I dont want to put in brushes that would bring problems with the motor so

Is there a way to establish what would be a compatible and safe brush kit set to buy for this motor?
thanks

 

I don't know of practical way to do this without taking the motor apart and examining the form, fit, and function of the replacement parts. Even after doing that there is no guarantee that they will work adequately or last as long.

 

A lot depends on how much you are willing to stake the life and health of the person bound to that chair when your cheap counterfeit components fail and perhaps cause a fire or other serious event.

 

I don't know of practical way to do this without taking the motor apart and examining the form, fit, and function of the replacement parts. Even after doing that there is no guarantee that they will work adequately or last as long.

I have access to the old brush so I can mesure its 2 size but not the lenght since it is used already. I do know that it is better to use manufacturer brushes but at 300dol (2 motors) that is too expensive .
If the replacement brushes last as long it is not a big problem.
What i wonder is if there could be damage to the motor by using brushes not from manufacturer.

And how to differenciate the very cheap brushes from the ones of reasonable quality.

The manufacturer does not want to give any info on the brushes spec.
How to approch this? thanks
It seems like there are grades and metal composition to determine, how to do that?

 

Who is "the manufacturer" -- the manufacturer of the wheelchair, or of the motors?

Use the information on the motor data plate to look up the specifications for the brushes. You can also contact a brush supplier or a motor repair shop and give them what information you have, perhaps taking the old brushes to them to have them examine them to estimate their specs, to find a (hopefully) suitable replacement.

If you use the wrong brushes, too hard, too soft, not designed for the current density, etc., etc., it can cause damage to the motor, possibly over time or possibly in a few days. The damage might be minor, or it might be catastrophic.

It again comes down to what is your tolerance for risk/reward. Is saving a few hundred dollars worth the risk of complete failure of the motor after a short period of time, possibly including overheating and flashover and the attendant risk of fire? Do you want to be sitting in the chair, out and about, when that happens? Do you want to be stranded if the motor fails? Can you get out and away from the chair if it catches something on fire? Is that risk worth the few hundred dollars you saved?

 

For a wheel chair, I would expect to see brushes with fairly high copper content, If using ones that are too soft, i.e. high in carbon, the wear will be higher than normal.
Have you tried Helwig Carbon, BTW?

 

Not an expert, but the brush you showed in you other thread did not look worn out to me. Can members more knowledgeable please weigh in?

 

Not an expert, but the brush you showed in you other thread did not look worn out to me. Can members more knowledgeable please weigh in?

Yea, doesn't appear too drastic a wear yet!

 

Ok I will try to call Helwig Carbon to see if the can have info,
When a brush is too worn out , Is the only risk the risk that the metal part that connect the coper wire to the brush and spring come directly in contact with the armature?
Lets say that the chalk part of the brush would endup worn to only3 or 4 mm, is there also a risk that part of the chalk would break and go loose into the motor or is the chalky part solid enough to stand its ground until 2 or 3mm thick?
Thanks

 

Yes it the metal part reaches the comm it will damage it, unless it is fortunate enough to disable any connection, If the carbon wears down, you usually get intermittent operation and-or carbon brush to comm arcing.

 

As @BobTPH pointed out, they do not appear to suffer from excess wear yet??

 

HI Max,
At moment I dont know the original lenght of the chalky part of the brush . Hence I m trying to find new ones and to learn how many millimeters long can we use brushes whithout having problems.

 

the original length cannot be longer than spring in its relaxed state or in this case length of the wire inside the spring. that brush looks good, very little wear. should last a while till it is 50% of what you have now. and if looking for substitute, any brush of same size should work. there is tons of motors using same brushes. check Automotive parts too, or if desperate, buy one of kits on Amazon. for $10-15 you will get bunch of different sets. something is going to fit.

 

Although these are typically high current motors which in most cases have brushes with higher copper content than most lighter applicatins