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 Posted - June 07 2017 : 6:49:22 PM
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I recently picked up an F-unit chassis for next to nothing. The good side is, the loco works nicely by itself, crawling at low speed, and probably doing a scale 120MPH at top speed. The bad side is, it could not pull itself out of a wet paper bag, losing a lot of power with only half a dozen freight cars behind it, while making itself hot in the process and/or tripping the internal breaker inside the DC controller when that also gets hot (which is rated at a paltry 360mA but works perfectly well with every other loco, even with 2 or 3 running together). I'm not used to seeing an Athearn being creamed by PowerTorque and Bachmann pancake motors which only drive a single truck!
The first thing that came to mind was that the original magnets have gone weak in their 50 or so years of running, and I was wondering if anyone has ever used rare earth/neodymium magnets in a vintage motor such as this. I believe this one predates the gold motors. It would be nice to keep the original motor going, as it seems to have plenty of life left in it.
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Country:  Australia ~
Posts: 89 ~
Member Since: April 29 2016 ~
Last Visit: May 27 2023
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Posted - June 08 2017 : 01:10:16 AM
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Check the axle gears by holding the flywheel and turning each wheel to see if they turn. If any turn you have cracked gears. This will keep the loco from pulling very well. I am unaware of any magnets that will fit. A replacement motor or an after market can motor is the common solution. These older motors usually draw pretty high current
Regards, John
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Country:  USA ~
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Posted - June 08 2017 : 06:06:26 AM
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Thanks for the reply - the gears are all good however, no binding or anything. I also have a spare set of gears from a Baldwin S-12 which was converted to a dummy (it had no motor when I bought it), which is now a track cleaner.
The only loco I have with cracked gears is a 1980s Bachmann Santa Fe F7, and no-one stocks gears for these (I need both axle gears). I bought the F7 on eBay as "dead" for parts (specifically, the gears) to repair an F9, but I ended up getting the F7 working as well, so I'm back to square one of finding gears again!
You're right about the ability to swap magnets in these old Athearn motors though, the magnet itself doubles as the motor housing - I would have had to fabricate an entirely new housing if I did try to replace the magnet with rare earth magnets. It looks like a can motor conversion might be the only way if I want to pull a proper train with this one. With six passenger cars behind it, the loco runs at about half speed at 12V compared to running alone.
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Country: Australia ~
Posts: 89 ~
Member Since: April 29 2016 ~
Last Visit: May 27 2023
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Posted - June 12 2017 : 10:20:58 AM
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| You may have the windings going bad. One of the wires may have a partial breat in it. This whould cause excessive arching, heat and loss of power. Basically the fix is a motor swap. That said finding a parts BB at a show or EBay is not to difficult.
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Country: USA ~
Posts: 332 ~
Member Since: August 28 2010 ~
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Posted - June 12 2017 : 11:51:23 AM
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It is my understanding, when a motor gets hot, it is because of a weak magnet. I have never myself used the Neodymium magnets on this type of motor, but I do recall seeing someone machine out a slot or two in the original magnet to fit new Neodymium magnets and revitalize the original magnet. Otherwise it's addition gets kind of tricky in this application. A purchase of a $5-$10 dual axle can motor might be another option though.
Sean
"If everything seems under control, you're not going fast enough!" - Mario Andretti!
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Posted - June 17 2017 : 3:47:35 PM
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| Well that was an almighty fail for the weekend. I reassembled the motor last night, and when putting the top brush clip back on I didn't put it on straight enough, the clip came apart and the top brush spring went flying into the next suburb! A day later and I still can't find the spring - I think it really is time to put a can motor in this one!
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Country: Australia ~
Posts: 89 ~
Member Since: April 29 2016 ~
Last Visit: May 27 2023
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Posted - June 18 2017 : 2:07:20 PM
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| Remarkable. Like to see the next phase.
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Posted - June 26 2017 : 5:17:04 PM
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| If it counts as a phase, I have a well-used and damaged F3 shell which fits, but it needs a new pilot and other touch-ups. I would really like to get this one up and running, the older and more worn out they look the better!
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Country: Australia ~
Posts: 89 ~
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Last Visit: May 27 2023
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Posted - September 15 2017 : 02:28:57 AM
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I still haven't sourced a can motor yet. For now I have turned the loco into a dummy. I managed to find the spring and the motor is working once again but I have insulated it so it won't use power while being dragged.
As I don't have the original draft gear boxes which snap over the original coupler mount, I have filed down the original mounts, drilled out the original hole for the box to fit and used some spare Bachmann truck screws to hold a Kadee draft gear box in its place, and it is now at the correct height unlike the photo at the top of the page.
I have not given up on this loco yet, I just haven't had much spare time to do anything lately.
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Country: Australia ~
Posts: 89 ~
Member Since: April 29 2016 ~
Last Visit: May 27 2023
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