How to replace the drive gear of an MTH tinplate locomotive?

Can either the worm and/or the spur gear be removed on your new set, if so I would drill out the old shaft to removed the old spur gear and then cut the old gear shaft out.

Once the bearing are clear and clean, I would slide the new shaft into place and reinstall the gears.

Otherwise you will have to cut the frame to release the bearing and shaft.

Good luck

Totrainyard, I might end up doing that. The only problem is that the gears seem to be permanently attached to the shafts. I have heard that metal gears can be removed from the shaft if you heat them up with a blowtorch, which I unfortunately don't have access to at this time. I tried using a soldering iron instead, but that didn't work. I'll have to find another way to heat them up. Anyway, thank you for the suggestion! 

The early drives on these locos aren't easily replaced.  You have to cut the shaft with a dremel and remove the pieces.  Replacements available from MTH come with the cross shaft, side drive gear and worm driven gear that is secured with a set screw.

Jon G, do you know where I can buy one of those replacement gear assemblies? The MTH website has a parts search, but I can't find the option to buy a specific part. I was able to find this part, which appears to be similar to what you described, but the sizes of the gears don't look like they match the ones on my blue comet. Is there a different part I should be looking for?

The complete motor for the #263 is available from MTH, $114.  I added it to my cart and it said it was available.  Since I don't really need one, I removed it from my cart.

https://www.mthtrains.com/part/TP-OE00042

John, I think that that part is for the version of this engine with an AC motor built into the chassis and with a mechanical E unit. The one I have uses a DC can motor with an electronic E unit in the tender. I'm not sure if it will work. 

Well, you're right, it was the only part number I found for the #263 motor.   Findi ng those gears will likely involve getting MTH to assist you, maybe call Midge and see if she can track it down.

I hate to be a PIA, but have you determined why the gear stripped in the first place?

If not, the new gear might get stripped also.

@Blackjack4935 posted:

Jon G, do you know where I can buy one of those replacement gear assemblies? The MTH website has a parts search, but I can't find the option to buy a specific part. I was able to find this part, which appears to be similar to what you described, but the sizes of the gears don't look like they match the ones on my blue comet. Is there a different part I should be looking for?

The part you identified is for Std Gauge ProtoDrive motors.  They have both the individual O-gauge worm driven gears and the whole assembly.  Once you replace it with the new version, the worm driven gear will be easily replaceable.  Deb had a bag with those new gear assemblies and there is a part number assigned, but it may not have been posted yet.  Still furloughed, so I can't help with the part number, but Midge can check with Deb if you email her.

As for why it wore out, it's sacrificial so the worm gear on the motor doesn't wear out.  But, it's Chinese brass, so don't pull heavy loads, don't run it in a museum setting and keep it lubricated (not the easiest thing to do).

Roy, I'm not exactly sure what happened, but my theory is that the grease that was on the gears got old and started to harden, thus damaging the gear. When I took the locomotive apart, the motor's worm gear was almost completely submerged in thick grease which had turned green. I've removed almost all of the old grease, and I plan on doing a more thorough cleaning before I put in the new gear, so hopefully this doesn't happen again.  Jon, I had a feeling that the gear I was looking at was for standard gauge. I'm glad I didn't buy it right away! I contacted Midge about this a while ago, but I don't think I ever got a response. I'll definitely contact her again, now that I have a better understanding of what to do.   

As Jon says, that gear is a very common replacement part in many of the tinplate locomotives.  I've done a few of them in both STD and O-gauge.  I haven't seen the locomotive represented here yet, but it does look like you have to cut the old one out as Jon says.

I did that one quite a while ago.  PITA.  I think I had to press it out.  Press gear off new shaft, and press back on.  G

So I went back and looked at my notes.  First, you can press the shaft off.  Gears are pressed onto a splined/swaged shaft.  I have replace gears on diesel trucks and other engines.  The key in reassembly is location of the new gear and using spacers to ensure it gets positioned correctly during installation.

The new part assembly MTH came up with is now TP-OE00147.  This is a complete shaft and gear assembly that will not require pressing.  I have one in stock if you needed it. 

To get the old shaft off, you could press out on the side opposite of the idler.  Use a spacer to keep the damaged worm gear from moving as the shaft is driven out.  G

@GGG posted:

So I went back and looked at my notes.  First, you can press the shaft off.  Gears are pressed onto a splined/swaged shaft.  I have replace gears on diesel trucks and other engines.  The key in reassembly is location of the new gear and using spacers to ensure it gets positioned correctly during installation.

The new part assembly MTH came up with is now TP-OE00147.  This is a complete shaft and gear assembly that will not require pressing.  I have one in stock if you needed it. 

To get the old shaft off, you could press out on the side opposite of the idler.  Use a spacer to keep the damaged worm gear from moving as the shaft is driven out.  G

G, thank you for the information. Do you think I could remove the old shaft with a hammer and punch instead? I don't think I have access to a press of any kind.

You tend to deform the frame if you try to press/punch it out without proper support, and due to the design it is difficult to support.  I had better luck cutting it out and then flushing out all the debris.

I was wondering about that Jon, looking at those pictures, I couldn't see a good support for pressing it out.

Sockets and vise.  While I had a lionel press I never used it.  I do all my work with the bench vise and various sockets and broken drill bit to press wheels, and gears.  Punching is not the method to use.  I do use the flywheel and wheel puller that Timko makes, but the internal gear swaps and such are just basic tools and the vise.  C clips and flat steel can be used as spacer if needed.  G

I don't pound things out unless there's no other way.  I do have a press, and I use it for stuff like this is there's a way to brace the surface to avoid bending anything that I don't want bent.  Looking at this one, I'd probably go with Jon's method and chop it out with the Dremel.  Since the replacement doesn't need any pressing, that avoids any possible damage to the motor frame.

OK, dremel it is. It may be a bit of a challenge, since the frame might get in the way, but I'm sure it can be done. G, how much would the replacement part cost?

$15 plus shipping, you can email me from my profile.  G

@GGG posted:

$15 plus shipping, you can email me from my profile.  G

Sounds good. I just sent you an email.

Thanks to GGG and the parts he provided, I was able to get the engine running perfectly again! I've held off on completely reassembling the engine though, because I just remembered that I need to replace the smoke unit. I talked to Midge about a replacement, and the only one she has at the moment has a brass funnel which does not match the one on my engine. Is it possible to remove the funnels and swap them?

Why do you think you need to replace the smoke unit?  Typically, unless they've run away and cooked the PCB, a simple rebuild is all that's required.

As for removing the funnels, some screw in, some are permanently mounted.  If you have one that's permanently mounted, it was pressed in, and removing it will leave it loose forevermore.

@gunrunnerjohn posted:

Why do you think you need to replace the smoke unit?  Typically, unless they've run away and cooked the PCB, a simple rebuild is all that's required.

As for removing the funnels, some screw in, some are permanently mounted.  If you have one that's permanently mounted, it was pressed in, and removing it will leave it loose forevermore.

I brought this engine to an authorized service center back in November because there were problems with the sound system. The guy was able to fix it, but he said that the smoke unit also broke. He gave the engine back to me and said he would call me when he found a replacement smoke unit. I decided that, since it's been so long, I should try to fix it on my own. I disconnected the smoke unit and tested it, and I couldn't hear the fan spinning. The funnel on this smoke unit seems to be pressed and glued into place. 

The fan is an easy to replace and cheap as well.

@gunrunnerjohn posted:

The fan is an easy to replace and cheap as well.

I'm not sure if the fan is the issue. I had just assumed that a component of the circuit board got damaged. 

This is a PS/1 locomotive?

@gunrunnerjohn posted:

This is a PS/1 locomotive?

Yes, it's PS1 with the old QSI sound system.

Unplug the fan from the PCB and use a 1.5V battery to see if it spins.  If not, replace the fan motor.  Next suspect is the LM92 package 5V regulator, those go out most often of components on that board.

PS-1 smoke boards can be repaired.  As long as you did cook the PCB so bad that traces disappeared or burned the fiber.  If you put a picture up, may have the top board assembly.  Worst case is the stack can be removed from the bad PCB if it is damaged.  Swedged and reinstalled in another.  Epoxy is your friend, if really damaged.  Normally though, just rebuild the unit.  I can do it if your not sure what is wrong and some of the electronic parts are damaged.  G

@GGG posted:

PS-1 smoke boards can be repaired.  As long as you did cook the PCB so bad that traces disappeared or burned the fiber.  If you put a picture up, may have the top board assembly.  Worst case is the stack can be removed from the bad PCB if it is damaged.  Swedged and reinstalled in another.  Epoxy is your friend, if really damaged.  Normally though, just rebuild the unit.  I can do it if your not sure what is wrong and some of the electronic parts are damaged.  G

The motor works fine when tested independently of the board, so the board has to be the issue. I can't tell which component

of the board failed, but some of the solder points in the right picture look burned. Maybe that has something to do with it.

I just read on another post that the 78l05 5v voltage regulator is what usually fails on these smoke units. I think it's the component that I circled in blue. Could that be the problem here?

Correct, the first component to replace is indeed that regulator.

I just replaced the voltage regulator circled in my last reply, but nothing happened. I then removed the plug with the red and black wire and attached it to the other socket, and I put the plug with the motor wires in the other socket. I did this because the socket that originally had the red and black wires was labeled "motor", so I thought I had the wires wrong spots. When I tried it again, the voltage regulator under the one I replaced started burning. Can this smoke unit still be salvaged, or am I better off just buying a new one?

Yes, but looking at your picture you are correct AC was plugged into the wrong spot so possible several of the transistors and cap are shot.  If you wan to send to me I can look at it.  I may also have that specific top board in my parts.  G

@GGG posted:

Yes, but looking at your picture you are correct AC was plugged into the wrong spot so possible several of the transistors and cap are shot.  If you wan to send to me I can look at it.  I may also have that specific top board in my parts.  G

I have a feeling it's the cap. I tested the 2sb772 transistor with my multimeter and was getting readings, so I assume that one's ok. I'm going to replace the cap, the KTA1266 transistor (which was the one that burned up), and the 5v voltage regulator since I still have a few left over.

The drive system and smoke unit are now fully functional again! Thank you all for your help! 

Now that everything is working, is there a way I can prevent the gear from being stripped  again? I'm worried that I won't have the option of buying another drive gear once MTH shuts down.

A tremendous amount of work - congrats on getting it running.

I hate to mention it, but it looks like the headlight was on at idle and went off when it started moving forward.

@Mallard4468 posted:

A tremendous amount of work - congrats on getting it running.

I hate to mention it, but it looks like the headlight was on at idle and went off when it started moving forward.

Thank you! The headlight only went out because I cut the power for a second to get it moving, and only brought the power back up a little bit so that it would start slow. These Proto-Sound 1 engines are conventionally controlled only, so the brightness of the lights will fluctuate.