Lamb thru-flow motor disassembly/brush bed in

[DesertTortoise]

Three questions actually. First, are there any guides, manuals or tutorials around describing how to disassemble and reassemble a Lamb through-flow motor for inspection and cleaning. On two of my current projects I can see the fans are dirty (you already saw how filthy the vacuums were, see Sunday Fun in the Kitchen Sink and Kenmore High Desert Restoration Facility.

Second question, if commutator brushes are replaced, how does one accomplish the 1/2 and 3/4 voltage bed in? What equipment should I buy to accomplish this task?

Third, is it safe to assume a new in the box Ametek-Lamb motor already has the brushes properly bedded in or did I ruin a new motor two years ago by taking it out of the box, putting into a vacuum and running it at full current?

Thanks.

 

[Gr8DaneDad]

I'm sure there are guides/manuals, but honestly I've never looked. Sure someone has them handy otherwise I can look when I'm on the computer rather than phone.


I use a standard rheostat for a ceiling fan.


I always check, but they should come properly seated. And really no harm, there will be a bit more arcing than normal until the brushes wear to the correct shape and a lot more carbon dust in the filter... but unless you ran that vac at full power for hours and hours under extreme stress, real damage is very unlikely.

 

[DesertTortoise]

Thanks for the tip on the ceiling fan rheostat. That ought to be easy enough. I reckon you measure the voltage at different settings of the knob using a VOM before using it on the motor? Put a little mark at whatever setting gets you 60 volts and another at 90 volts. Great idea, thanks.

Lamb has some pretty detailed data on brush bed in and brush life for second and third sets of brushes. They claim running a new brush at full voltage pits the commutator. They didn't specify a lenght of time for this to occur, just that it does if you don't follow the bed in process.

I have prowled the internet and Youtube for hours but cannot find any description of motor and fan tear down. Unfortunately there is an abundance of videos of these motors being burned into oblivion by running them at ridiculous currents and voltages. Pretty much any search related to vacuum motors brings these videos up. For the great unwashed, blowing stuff up is fun, fixing stuff not so much.

 

[Gr8DaneDad]

pitting of the commutator can and will occur from excessive arcing from the brushes. It's amazing how the same current applied differently can have such different results. However, it does take rather a good bit of time and with no load on the motor the arcing is substantially reduced. It is best to seat them properly with a stone and then fine tune at 50% voltage. Makes the difference between a 5 year motor life and a 50 year motor life.

 

[Gr8DaneDad]

D-T,


If you have the model # handy I can attempt to find you the exact documents for that motor.

 

[DesertTortoise]

One of them is 115923. Another is 116433 and a third is 115939 or 115923.

 

[DesertTortoise]

Did you mean the motor numbers or the vacuum model number?

 

[Gr8DaneDad]

Motor....


 


Well shoot, Ametek is not very friendly. I can find schematics, but more detailed instructions require the purchase of the entire service library and it's rather $$. Here is the schematic for the 115923. Basically you remove the fan shroud (usually 3-4 screws or bolts/nuts hold it to the mount) and then secure the armature and remove the retaining nut and the fans slide right off. I got to practice my first disassembly on a completely rusted/seized motor that I didn't care about salvaging so once I broke it apart, it was obvious how it was all connected and then I just jumped into the next one.