# Motor shaft worm gear



## little toot (Dec 3, 2013)

The worm gear came off the motor shaft on a used steam engine I recently bought. It appears it may have been glued on. The shaft measured .058" diameter and the hole in the gear is .063"; .005" clearance. I am new to N scale so I am not sure how they are supposed to be mounted. Does anyone have any experience in this area?


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## Howard1975 (Jan 6, 2014)

I believe they are usually a press fit, it's supposed to be nice and tight. That is how it leaves the factory. But what happens is, especially with older trains, is the different materials expand and contract at different rates. Metal expands at a different rate (based on temperature and humidity), differently then plastic. Overtime the two parts can loosen and come apart. Other times the gear can become cracked (even just a hair line crack) and fall off. 

There might be replacement parts available for your engine. Would need more information on your engine, such as model number and manufacturer. A picture would also help to identify your steam engine. 

Howard


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## little toot (Dec 3, 2013)

Thanks for the information, I thought it should have been a pressed fit, that is why I posted the question. The engine is a Con-Cor 4-6-4 Hudson. I am thinking that the gear may have been replaced, because it does not look like there is any wear on it. I have the motor apart to clean it and to check the brushes. The motor has about 1/16 lateral play in the shaft, this seem a little excessive to me. What do you think? When you buy something used, it could have a very mysterious past.

I bought another parts engine, when it arrives I will compare the parts to see if they are the same.


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## Howard1975 (Jan 6, 2014)

You're welcome for the information. Doing some research on your model, here is a site that reviews the Con-Cor 4-6-4 steam locomotives. 

http://www.spookshow.net/ccj3a.html

I have seen your other posts here at this forum, and I'm assuming this Con-Cor New York Central Hudson you are having problems with, is from the models you got from Mikek at this forum? If so, the Hudson looks in good condition cosmetically. According to the site I just linked above, there are a few versions of this locomotive around. The first couple versions were made by Kato in Japan, and imported into America by Con-Cor. The third version was made in China (not Kato anymore) for Con-Cor. You have one of the older models made by Kato, either first or second generation. 

I don't know anything about this particular model, I have never owned it -- other then what the website above says. Anyway here is the website for Con-Cor parts and service. 

http://www.con-cor.com/roundhse/nparts.htm

I have read this, and because you have an older engine, they won't have any parts for it, unfortunately. You could try various experiments with it, and see what happens. Hopefully you can get it working. 

Perhaps someone else with more experience with these locomotives will chime in and offer helpful advice.

Howard


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## little toot (Dec 3, 2013)

You are right about where I got the Con-Cor 4-6-4. When I received it I noticed that the cow catcher was missing. I was lucky to find a parts engine that had one. I received the parts engine and was working on it today. The results are as follows: the worm gears on both motors are the same. I measured the motor shafts and they seem to be the same diameter. I did not try to remove the worm gear on the parts engine. I think possibly they may have used some Loctite to attach the worm gear to the shafts at the factory.

Both motors looked identical. The parts engines’ motor looked like new, the armature wires were a nice purple color. The other motor wires looked a little burnt at the brush end. This may be do to over lubricating it. I cleaned the residue, the brushes and the cavities. I ran both motors out of the engines with no load on them. It took about 75% power to just get them to start turning. After a few minutes they got quite hot. I assembled the motor with the gear into the engine. It took about 75% power to get it to move. At full power it did not run very fast, at least not to me. I do not have a layout yet I was just running it on a 30 inch length of track. As per the link to the article on Con-Cor 4-6-4 I quote, “The motor has a well-deserved reputation for melting down with little or no provocation.”

Well maybe I will find a spot on my layout to park it on a siding for it does look good. Again thanks for your time and answers.


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## Howard1975 (Jan 6, 2014)

You're very welcome. Wish I could have helped more, but since both motors are barely working, and need 75 percent power just to get turning, I'm guessing they are essentially burned out. Looking at all the pictures again, I just noticed you have the first generation introduced in 1969. At least it looks that way to me. 

Sorry to see that both of the motors are burned up. Yeah you could find a spot on your layout to park it, such as a siding. It does look very nice cosmetically. 

Howard


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