Large Scale Central

LGB 0-6-2T: BadMotor, Bad Gears, Both, or Something Else?

Modeling Motive Power
#1

Aloha,

“Gustav,” our venerable 1980-s vintage LGB 0-6-2T, finished an adult beverage run on Sunday and, upon return to the rural community of Dogwallow, froze and made a horrible grinding sound as if he was eating his gears. I will warn you in advance, electric motor theory eludes me.

I opened “Gustav,” found no obvious sign of wear on the worm gears or the axel-mounted helical gears the worm gears drive.

I did electrical connectivity checks, all were OK. Putting test leads to each wheel pairing powered “Gustav” in forward and reverse. Thinking the motor may have just gotten bumped out of its cradle, I reassembled the old fellow, placed him on a test track and…nothing. Just, every so often, that grinding noise. If I removed “Gustav” from the track and powered him via test leads, around went his drive wheels.

There is a possibility minute wear over the years and a slight distortion of the motor shaft is an issue, causing the gears to slip and / or bind. The gear box in which this sits has a yoke on the upper tray that is supposed to hold the motor and shaft in place. There is no indication of warpage in the tray or breakage in the yoke. I am thus guessing this is the motor, but, do DC motors fail like that? Does enough internal resistance build up over the years that eventually, the voltage across the motor won’t turn the thing under load (Load in this case being a several pound locomotive.)?

A new motor is about $70 with shipping, and I can pop it in in 20 minutes. Gearing is about $80 for all three axels (2x geared, 1x ungeared), and, while unpleasant, I have totally stripped this engine down chasing an electrical fault (rotted contact springs and bent internal brass bus bars), so this is still within my skillset. I investigated shipping “Gustav” ($25 each way), and a site advertised “simple” repairs starting at $25.

I’d like to make just one order and be done with it, since shipping is a killer. Is it possible to isolate my issue based on the description above, make an order for one part, and be done with it? If I guess wrong, the shipping on the correct part will almost eat the cost of having a technician do the job in the first place, and I am out the money for the part. On the other hand, if I guess right, the savings are considerable.

Thanks in advance for tips and advice!

Eric

LGB 2085D European Mallet runs rough moving forward but runs fine backwards
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#2

Hi Eric,

This summer I had an LGB Mallet do something similar. At about half throttle it would start making a chattering noise and then one of the blocks would quit. On the bench, the motor would run OK but once the voltage was increased up to about half throttle (12v), or a resistence was put on the drive train, one of the trucks would just lock up. I took it apart and hooked it up to an ammeter and tested it again. One of the motors would run fine until a voltage increase or load and then the ammeter would spike way up past ten amps. The motor itself would make all sorts of “chatter” noises and then stop and start to smoke. Lots of sparks off the armature too. YOu might want to do a similar test if you have an ammeter. I think the motor bushings were worn out and the motor was shorting out under the right conditions.

I replaced both motors and the loco runs great now. Both new motors draw way less current than the old pair. In my mind, for a loco made in the 80’s or 90’s, this was a reasonable cost.

If you’re able to test your loco and get similar results you could order a new motor. You might also find another running loco on Ebay and turn one of them into a “parts queen” - this might be cheaper than ordering and shipping new parts.

Just my two cents

Mike

#3

Well, with close to zero expertise in this, is it possible the gear is loose on the axle? It sounds like everything is OK until the least bit of resistance is encountered. I would first check to see if the gear rotates freely on the axle (but remember, I have next to nothing as far as experience goes: I can’t tell if you need a new gear or if you can possibly repair it…)

#4

Mike,

I do have a multi-meter that measures amperage. I don’t have a baseline for current draw; I suppose a recently repowered “Stainz” might be close. Thanks for the e-bay tip, too. I have been looking to build a parts box, so that is an option on a not-too-old wreck.

Aloha,

Eric

#5

If I remember correctly, When I throttled each motor up, they ran at about 1.5 - 3 amps depending on speed. Once the throttle went up, the bad motor would peg my ammeter and stop. The new motors draw a little less than 1 amp each at about half throttle. this was a little higher with a load.

You could also check your stainz as a baseline. I did the same with my 0-6-2.

#6

I have Mogul that died on me. No noise, but the motor works fine when I bench test it. But in the locomotive its dead. Yes, its getting voltage in the locomotive, it just can no longer run with the load of the gear train on it.

#7

Gents (can you tell I am not at work today?):

Found the original tech manual, albeit in German (luckily, my rusty second language). The current draw(Stromaufnahme) for the m2070-series is 650-850 mA. No data on what the number correlates to in terms of what the loco should be pulling! For what it is worth, Mike, your mallet, assuming it is m2085, should’ve drawn 1200-1500mA. I will see what “Gustav” draws tonight, both on the rails and in mid-air. If that doesn’t work, I’ll crack the housing open again and see if those gears are frees-pinning as Bruce suggested.

Back to CINCHOUSE’s list of tasks!

Eric

#8

Oh, the above current information is for what I believe is the average (Durchschnittswert) voltage (Spannung) if 12 Volts DC.

#9

OK,

I took a Stainz out and saw that it reads about 20 ohms across wheel sets. If I am applying Ohm’s law correctly, this is about right. Old Gustav varied, from about 40 ohms to several hundred. I opened him up again and inspected things more carefully:

  1. Resistance across the motor. 4.5 ohms
  2. Inspection of forward gears. Minor deformation on the forward axel’s gear. No idea if this was there yesterday.
  3. Inspection of after gears. One was loose. I retightened it. No idea if this was the case yesterday, either. At any rate, with the motor out, I can spin the wheels and see all gears rotate.
  4. Other. Missing the after thrust bearing. This motor sits pretty securely, and this part has been gone for a while, or I would have had issues earlier.

For lack of anything better to try, I did compare things to Stainz.

  1. Resistance across the pickup shoes. On this Stainz this is about 15- 20 ohms, which, with an average voltage of 12 Volts, is roughly OK. Old Gustav showed anywhere from 10-s to 100-s of ohms, depending upon wheel sets.
  2. Amperage drawn. OK, I thought I could just put the loco on the track, put a lead on either side, and get the current. Am I missing something? Anyway, underway, the Stainz was showing .001-.002 mA, which makes no sense. Gustav was pulling .002-.004 mA, which is at least more, even if the units don’t seem to make sense.

With allowances for the good possibility I totally hosed up using my multimeter, I am pretty stumped. I might be sucking up those shipping costs…

Eric

#10

when measuring voltage, with a train on the track, you put the test leads on each rail… this is becaue voltage is potential, or like water pressure, you could put a water pressure meter anywhere in your plumbing system.

measuring current means all the current going through the motor must also all go through the meter… like your home, your water meter is out by the street, and all the water going to your house must go through your meter.

so you have to put the meter between one of the power supply outputs and the rail that the power supply used to go to directly.

be sure to start on a 5 or 10 amp scale… in this case you can damage the meter if you use the wrong scale.

Greg

#11

If you connected the meter across the rails while in the current mode (amp range) you may have blown the fuse that most digital meters have as protection.

#12

I wasn’t going to mention that right away… hoping for the best…

#13

Nothing like a bonehead mistake to gain knowledge. I’ll test the multimeter later…

I’ve been reflecting on the gearing, too. I don’t think that helical gear should move at all on the rear driver. It doesn’t on the forward driver. If it is slipping, though, I would have thought the gear would’ve just spun and not bound.

Have a great weekend!

#14

Update…

First, the ammeter. I guess the locomotive has to be standing still to test this, as it read 0 until a train rumbled over, came up to 4mA, then when back to 0. I need to review the GR article on how to use the things. On the upside, the Voltmeter still works.

Second, the way forward. I am beginning to suspect I am chasing multiple age-related faults. I have replaces some of the spring-loaded shoes that take power from wheels to motor, and I had to re-bend some of the interior buses to make solid connections during that earlier repair. With one gear set possible damaged, and another showing wear, I am considering sucking up the postage and just having “Gustav” thoroughly troubleshot and fixed.

Still pondering my options on this one…Lots of “Stainz” action in the meantime!

Aloha,

Eric

#15

So, maybe you are reading the meter wrong, perhaps it was 0.4 amps… definitely not 4 milliamps.

Remember all the electricity must go through the meter, so if you have a power pack, normally both wires go to the rails.

Disconnect one of the wires to the pack and connect one of the meter leads to that wire. Connect the other lead to the power pack. Again, all the electricity must go through the meter.

Be sure you are set on the amps scale…

If you can provide a model number of the meter or a picture maybe that will help.

Greg

#16

Greg,

Thanks. May not get to it until this weekend unless I can fire up the RR sooner. I am finding it is simpler to just work by daylight outside.

eric

#17

Since the model 2070 was mentioned, I would assume the motor is the older version which has a red and black plastic holder for the motor brushes. These can be removed by removing the small black ring at the end of the motor (look closely as there is a small flat surface on the inner diameter that will match up with the metal motor housing).

Now the 2 plastic blocks can be removed. Make sure the spring loaded brushes move freely. Now take a small exacto sharp blade and clean the debris out of the commutator gaps. At this time I also polish the commutator with a piece of a discarded track cleaner ting.

Reassemble and run the motor a short time before installing in the engine to reseat the brushes. DO note the alignment pin on the motor plastic ring to fit in the slot in the motor block. Failure to do this will make the end of the motor not mest properly with the plastic gear and cause it to strip or jump teeth resulting in an out of quarter engine (a very common problem I keep finding in users engines).

Also note that the newer motors with all metal casings do not need the bal bearings at the end of the motor shaft, only the older motors needed these which did not have thrust bearings. If the plastic type brush holder motors have no lateral movement of the armature then these bearings are not need either.

#18

Dan,

Yes, that is the motor.

On the mechanical side, the helical gears that are on the aft-most drive wheels does spin freely around the axel. It seems that this can be hand tightened, but this hand tightening doesn’t seem to hold. Is it time for a new wheel set?

Thanks,

Eric

#19

If you can pull the motor, hold it up to your ear and twirl a motor shaft. It should sound nice and smooth. If it sounds rough or feels rough, it’s new motor time. I have replaced several LGB motors over the years using this unusual method, and then they ran fine. Or you can bench test the motor (only the motor–no axles or gears attached. It should run quietly. If not, same thing as above.

#20

OK,

We can all breathe easily; I did not blow my multimeter! Beyond that, after removing the motor, tonight’s troubleshooting showed:

  1. I can spin the motor by hand with little noise and no resistance.
  2. At the “DC10A” setting, I am getting a reading of 0.135 at 10.1 V. I am assuming that I multiply this number by “10” to get a reading if 1.35 A. I put Ohm’s Law to work, and those numbers seem about right based on the manual’s range as listed above.

I am beginning to wonder if old “Gustav” ate “his” gears. I have also written the folks at Trainli for their input since, as I mentioned, shipping to Hawaii is a bummer, and I’d like to order the right part the first time or just eat shipping once, send the old fellow in, and re-baseline the loco.

At least the stable of Stainzes are standing by to do service and have filled the gap admirably.

Thanks again to all for the troubleshooting help. I am learning a good deal from this.

Enjoy your week, everyone!

Eric