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 Posted - March 24 2009 : 8:38:01 PM
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I have one of those 'deck of cards' shaped Rivarossi HO Cab Forward electric motors, (4154 4 is stamped on the case), that appears to have very little run time on it [per examination of the brushes & general condition]
However it is not running very strongly & from turning it over by hand I suspect the magnets are 'tired'.
Is there any way one can zap them & thereby restore some grunt??
Do the magnets lose their oomph over time??
Tanked
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Posted - March 25 2009 : 12:41:15 AM
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I had seen an article on how to build a motor remagnitizer (can't recall the mag) .
You could also slide the magnet out and replace it with a stack of neomagnets.
Ray
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Posted - March 25 2009 : 08:39:27 AM
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quote:I had seen an article on how to build a motor remagnitizer (can't recall the mag) .
You could also slide the magnet out and replace it with a stack of neomagnets.
Originally posted by Ray Marinaccio-March 25 2009: 12:41:15 AM
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Ray - where do you find the neomagnets??
Thanks
Tanked
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Posted - March 25 2009 : 11:31:57 AM
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quote:
Ray - where do you find the neomagnets??
Thanks
Tanked
Originally posted by TankedEngine-March 25 2009: 08:39:27 AM
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Here's a site that has all shapes and sizes.
http://www.supermagnetman.net/index.php?cPath=39&osCsid=722a1af3b55f738276e142247d693560
If you can't find one the right size they can be stacked together.
Steel shims can be used to take up small gaps if the magnet or stacks don't add up to the exact length.
Ray
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Posted - March 25 2009 : 2:46:48 PM
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quote:quote:
Ray - where do you find the neomagnets??
Thanks
Tanked
Originally posted by TankedEngine-March 25 2009: 08:39:27 AM
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Here's a site that has all shapes and sizes.
http://www.supermagnetman.net/index.php?cPath=39&osCsid=722a1af3b55f738276e142247d693560
If you can't find one the right size they can be stacked together.
Steel shims can be used to take up small gaps if the magnet or stacks don't add up to the exact length.
Originally posted by Ray Marinaccio-March 25 2009: 11:31:57 AM
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Thanks Ray.
Interesting site. Will look into that.
Had another fiddle with it this morning wired up to the brush housings & noticed that if I pushed down gently on the brush that is wired to the rear pickup, the revs lift, but no change if I push on the other brush.
I have had brushes out & they look ok, not worn down.
Can one get 'stronger' brush springs anywhere? Could that be the problem?
The commutator appears flat, as best I can tell with that pancake commutator shape. There is no binding when I turn the motor by hand.
Its a bit of a head scratcher - motor runs ok hard wired to a power pack, then stops & needs a nudge to get going again.
Erratic.
Magnets or electrical??.
Tanked
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Posted - March 25 2009 : 10:00:23 PM
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Being curious I stripped the motor down this evening & didn't realize the shaft was ball raced front & back.
The ball bearings look like cake sprinkles - , bl--dy small.
I have 10 for the front, but only 5 for the back.
I have a hunch I should have an even number of ball bearings for the rear - anyone pulled one of these apart before & know how many ball bearings there should be front & back??
Before stripping it down I had it on the alligator clips - it would run ok initially, then when I stopped it to reverse direction, it wouldn't kick in until I flicked the windings housing.
Perhaps some binding somewhere or it had dropped a bearing??
Tanked
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Posted - March 26 2009 : 01:08:13 AM
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Check the wire connections on the commutator. It sounds like one of the armature windings is dead.
Ray
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Posted - March 26 2009 : 09:30:18 AM
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quote:Check the wire connections on the commutator. It sounds like one of the armature windings is dead.
Originally posted by Ray Marinaccio-March 26 2009: 01:08:13 AM
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Excuse my ignorance, what is the testthat will tell me its dead??
I think you areon to it- what is happening is consistent with what you are saying
Thanks
Tanked
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Posted - March 26 2009 : 09:58:39 AM
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The first thing would be to look at the solder connections to see if there are any obvious broken or burnt wires or unsoldered connections.
Further inspection would be done with an ohm meter to check the resistance of the armature coils at the commutator.
Usually a visual inspection will reveal the problem if there is one.
Ray
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Posted - March 26 2009 : 11:41:06 AM
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quote:The first thing would be to look at the solder connections to see if there are any obvious broken or burnt wires or unsoldered connections.
Further inspection would be done with an ohm meter to check the resistance of the armature coils at the commutator.
Usually a visual inspection will reveal the problem if there is one.
Originally posted by Ray Marinaccio-March 26 2009: 09:58:39 AM
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ok
If I end up using an ohm meter, presumably I will be looking for consistent resistance across all coils.
I assume a faulty commutator is terminal if I can't find a fixable broken wire?
Thanks
Tanked
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Posted - March 26 2009 : 4:15:18 PM
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Tanked,
There should be an even number of ball bearings in both races. Perhaps someone disassembled it and lost 5 of them, which would also explain the weak performance, since a good portion of the magnetism is lost when the armature is removed and magnetic field is broken. Most open frame motors were given a boost after assembly with a magnetizing coil like Ray mentioned.
Your best bet would be a stack of rectangular Neodymium magnets to replace the old Alnico magnet. Drop them into the top after you get the motor reassembled, because you'll never keep the bearing in their races with them installed. When I was a kid I made the mistake of trying to take one apart, and the bearings flew onto the magnet.
There's a guy on eBay who sells the 1mm bearings you need, but I ordered from him recently and the bearings were either pitted or out of round, so I don't think he's a good source. They made a horrible noise in the C-Liner I used them in.
The Tyco Depot
Edited by - NickelPlate759 on March 26 2009 4:24:17 PM
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