Can I determine the speed of a 12V DC motor from windings?

[Billy22Bob]

I've opened it and need to know what rpm it is so I can sourrce a new one....
anyone....?
its a johnson motor
66101/390901.

 

[mbarazeen]

you better serach with the model number written on it, for DC motors not possible to tell the RPM (at full voltage) just by looking at the winding /poles. (like AC induction motors). number of turns/pole & current in the winding when at full speed (no load) together with airgap charecteristics (including core charesteristics) will decide the RPM.

 

[MikeMl]

In a word, NO.

 

[Billy22Bob]

Well - things are looking up.....

this is a similar problem with our cars....anyway another owner has posted a possible replacement motor he used in Ocotober - but I want to check the specs 'cause the serial numbers are slightly different.
Mine has

66101
Johnson
390901

and the one this guy reckons will do the job is here...
**broken link removed**

66430
9176AK
3H0144

but has a slightly different code. He also reckons you have to file a flat on the shaft to fit into our application/pump. So that may be all the difference between the 2 codes - but it may not be.
So I'm rying to check the current draw and rpm of the respective codes - maybe they are the same.

BTW - I also tried over at Mabuchi in Japan 'cause someone said they were simply rebadged...not sure if that's quite true or not. No luck, 3 motors - nothing like the specs for the 664030

 

[Billy22Bob]

Well - you wouldnt believe it!!!!....

I was curious why all the armature segments were showing zero resistance to one another....
discussed this with a guy at work today and he indicated it might be supposed to be that way.
We had a bit of a navel gaze and he tried to convince himself and myself that the wire should be continuous.

Well I couldnt get this continuity from the main terminals when I had pressed the brush arms in as far as I could. So in the process I broke an arm. Decided to break the other on e and try to connect the 12V aligator clips to the remnant brush pieces, set them against the armature and wacko!!....away she went.

Well of course the end cap and brushes are stuffed, but it lends me to think that I can buy any old motor with a similar end cap, dismantle it and stick it onto the old PM body and should work! Could be going by tommorrow if I'm prepared to fork out $15 for a motor so I can actually dismantle it.

 

[BrownOut]

Did you find a motor for $15, or is that just your budget?

 

[Billy22Bob]

Well you can go cheaper....

$10 would be my budget however if I want to buy today at the local electronics store - I'll have to pay $15
If I buy on line and wait...wait...I could by it (or a couple) for $10 here
**broken link removed**