Help with newest GS-4?

[Peavine]

So I wanted to do a little experimenting with steam. Have lots and lots of diesels, but decided to make an impulse buy at the hobby shop today. Picked up a union pacific FEF-3 # 838 and a Southern Pacific GS-4 #4433. Right out of the box, the FEF-3 is exactly what I would expect from the rest of my hundred or so Kato locomotives. Slow speed control is amazing, it is flawlessly smooth and right out of the box was incredible. Then I put the GS-4 on the track. Didn’t start up until it had about 3 1/2 V on it and I gave it a little tap. Has rather poor slow speed, and clicks when it goes down the track. Just not super smooth. Is this to be expected with a brand new locomotive? I started looking around on this site for GS four problems and it seemed like most of the issues were with the older runs, but this certainly is not what I expected from Kato. I’m gonna stick 15 or 20 cars on it and let it run for an hour to see if it smooths out any, but do any of you have any suggestions for smoothing out this newest version? Thanks in advance.

[Peavine]

Never mind, I was going to post a video of it’s sloppy running, but I can’t figure out how to put a video on here

[Jbub]

Never mind, I was going to post a video of it’s sloppy running, but I can’t figure out how to put a video on here

You have to link to a video hosting site like youtube or vimeo.

[peteski]

The high starting voltage is likely due to the fact that GS-4 uses a standard motor, where FEF3 uses a coreless motor.

GS4 motor is the same motor used in the NW2 diesel.  Design similar to standard Kato motors, but it is smaller, has a skewed 3-pole armature, and instead of standard magnets is uses those super strong rare earth magnets.  Other than the higher starting voltage I would expect it to perform well.

[greenwizard88]

To answer your question, without even watching the video, no. The GS-4 has never had running issues. It's had DCC-ready issues (read: It wasn't), but the drive train itself was... what I would call "good enough". I'm not certain that it's as good as the FEF, but it's certainly good enough to pull the full Daylight consist without trouble.

As far as it not being super smooth, can you see anything binding? How are the traction tires on it, are they both still there? Are you sure that it's the latest run, and not new old stock that just needs to be run in? It's been a while, but IIRC the tender has power pickup as well as the drivers. What happens if you keep the tender on the track, but lift the drive wheels, does it still click, or require power before it starts running?

[peteski]

To answer your question, without even watching the video, no. The GS-4 has never had running issues. It's had DCC-ready issues (read: It wasn't), but the drive train itself was... what I would call "good enough". I'm not certain that it's as good as the FEF, but it's certainly good enough to pull the full Daylight consist without trouble.

Actually, other than the problem with the first run blowing up decoders (due to drivers shorting track power to the motor circuit), there was a big problem with the driver axle tubes cracking.  But all those prolblems have been addressed in the subsequent runs.

[mmagliaro]

My following statement applies to a batch of 6 or so of these from the run with the cracked axles that I fixed up for people.
None were DCC.
And not a one of them would run smooth under 15 mph, even with the gentle half-wave pulse in my throttle.  Once they got up to 20, they were great.

I'm sure a decoder with back emf would help here, but the bare mechanism and motor do not impress me.  I honestly think it is geared too high to provide smooth start-up and low-speed running.  And probably, since it's a passenger engine, people may not care so much about that.

[SkipGear]

Too add to Max's statement, the motor's suck. I have replaced 4 motor's in club members loco's now. The rare earth magnets almost seem like they have Zamac disease. The magnets will swell and start rubbing the rotor on the armature. I've seen it happen 4 times now.

Mine is the hardest loco I own to get chuff timing right on the sound decoder. They need a new motor design.

[mmagliaro]

Too add to Max's statement, the motor's suck. I have replaced 4 motor's in club members loco's now. The rare earth magnets almost seem like they have Zamac disease. The magnets will swell and start rubbing the rotor on the armature. I've seen it happen 4 times now.

Mine is the hardest loco I own to get chuff timing right on the sound decoder. They need a new motor design.

Fascinating Tony.  So, you probably know this, but... neodymium rusts like mad if left exposed to open air, so those magnets are all plated with something to protect them.   At the cheap end, they can be plated with zinc.   But better ones are plated with nickel (actually, 3 layers, that go nickel-copper-nickel).  I wonder if the plating on those motor magnets is shoddy, and it is either contaminated zinc, or it is letting the magnets rust inside, which of course will eventually swell up and force through the plating.

What do these swollen magnets look like?  Got any pics?  Now I'm curious.

And unfortunately, that motor is slimmer than your typical Atlas/Kato motor, so you can't just swap it with one of those without hacking into the frame.  Crazy... That is a big engine.  There's plenty of room for a nice big motor, and they didn't take advantage of it.

[tehachapifan]

Are we talking about the latest run developing motor problems or earlier runs?

[peteski]

Yes, that motor is a bit of an oddity.  I wonder if it was designed to fith in the hood of the NW2.  Not sure is any Japanese prototype models use that motor.  I'm also not sure why they used it in a large steam loco like a GS-4.  Maybe because of its skewed armature and those strong magnets, the motor has more torque than the standard Kato motor?  Maybe we could get @mmagliaro  to run some performance analysis on it?

FEF3 (the next GS-4 size American steam loco made by Kato) received a coreless motor (which I suspect was initially used in Kato's H0 P40 diesel).  Now Kato uses that motor in their Japanese prototype steam locos.

I have few of those GS-4 motors,  and none of them have any problems with the magnets. But I do have some individual rare-earth magnets (from eBay) which have the problem of the plating bursting open. As long as the plating keeps the moisture out of neodymium, those magnets will be problem free.

[tehachapifan]

Bump for my previous question, as I have the newest run. Do I need to worry about the motor?

[mmagliaro]

Bump for my previous question, as I have the newest run. Do I need to worry about the motor?

I don't think we know.  Tony might, as he saw this swelling phenomenon and would know what era motors those were
more accurately than me.
--
All I'll say about the motor is that if I owned a GS-4, I'd take the dimensions of the available space in that frame and put a better motor in there, probably even a gearhead if I could make it fit, to get more torque and lower speed.  But that's just me - Any time an engine can't crawl off the starting block smoothly, I want more gear reduction.

[mmagliaro]

Whaddya know!  I forgot about this:
A Kato GS-4 remotor project, putting a Maxon 1017 + 4:1 gearhead in there as a replacement, by carlso.
No, it's not a "drop in", but it fits pretty well.

https://www.therailwire.net/forum/index.php?topic=35693.45

The thread shows fitting the motor in there, but unfortunately just stops before the project is completed or
we can see it running. But I see no reason why it would not work.  A 1017 (or a Faulhaber 1016) can clearly fit in there,
and if you mate it to an 8mm gearhead (instead of the standard 10mm), it fits easier because the gearhead goes where the old flywheel was, which was a smaller cavity diameter than the motor.  If you use a 10mm gearhead, you'll have to do more frame reaming.

[SkipGear]

Bump for my previous question, as I have the newest run. Do I need to worry about the motor?

As far as I know, most of them I repaired were from the first run. The motor's I have replaced have not failed again.

As to the failure of the motors, the plating is flaking off and the magnet underneath is turning to powder. (Finally found the one I recently replaced in my GS-4, thought I had tossed it.)