MTH Y6b Steamer Shorts Out over 072 Lionel Switches.....

I'm going to assume your Lionel O72 switches are the tubular type? If this is true this is created because the center rails sit about 0.100" to 0.080" higher than the outside rails. (Put a straight edge across all 3 rails and you will see how it teeters on the center rail. There are three ways to correct this;

1.) using a ballpeen hammer carefully tap on the center rail until it matches the height of the outside rails (I am quite certain you do not want to do this, heck I don't even like to suggest it!). Besides, it will create a bind on the point rail assembly and prevent the switch from working properly

2.) Replace the switches with the O gauge O72 switches in stock at Lionel now (I oversaw that production and made quite certain the center rails matched the height of the outside rails!)

3.) Place a small piece of electrical tape on the frame of the loco where the roller is shorting out, to prevent the short from occurring. Ideally it would be best to use the liquid rubber that you dip tool handles into, as it sticks way better than electrical tape.

The problem is created by the very narrow space between the frame of the loco and the roller. The problem does not manifest on other locos because this space is greater on those engines. Sorry I don't have better news for you!

Thanks,
Mike

Hello Mike!

Thank you so much for the quick response! You are correct......my layout uses tubular track throughout; including the switches (I keep forgetting to mention that). 

My 072 switches are across a variety of years.....some as far back as 1990. It's funny you mention replacing some of the switches. I ran short of them and order several a while back (a year ago?). What I received was a mix bag from different years (I'm guessing the store sold what ever they had in stock). 

I know this because some switches had LED bulbs with circuit boards to convert/reduce the bulb voltage and had replaced the mechanical "slide" mechanism with micro switches. Others (in the same shipment) had incandescent bulbs with mechanical "slides" mechanism. They all worked and work well....so I've had no complaints until now. I still believe it's a design flaw with the engine itself though; especially in light that it hasn't happened with other MTH engines.

Hmmm.....never tried a different MTH steamer! I have a 4-8-4 somewhere that I'll try and see if I encounter the same problem.

In the mean time, I will take your advice and add some electrical tape to the frame above the pick-up roller and see if that fixes the problem.

Thanks again for your help and suggestions....... 

Mike is spot on. That center rail is just a hair taller than the "running rails" and is causing your problem. Been there, done that! I had that issue with my RK Y6B on my old layout. I yanked all of the switches out and replaced with Ross switches. Best move I ever made and I've been with Ross ever since. Problem solved.

There was an issue with MTH starter set loco, the 4-6-0 when it was reintroduced circa 2011 (it was done one year with PS2 and then PS3) where the gearbox literally dragged on the center rail and bottomed out the engine on ALL tubular track, not just switches. That unfortunately went right back to me dealer. Review of a new production loco in a set the following year showed a re-tooled gearbox area and no issue.

Alan and SJC......

Thanks for your responses as well! They confirm that this problem is definitely either a design flaw or manufacturing flaw with the engine itself. 

Makes me wonder how MTH tests these engines (kinda like Microsoft testing software). Do they test over switches at all? If so, do they test using only MTH track/switches/etc. or do they test using a variety of manufacturers products.

I took a 2nd look at the bottoms of both driver assemblies. They look like they're a one-piece casting. Little chance (if any) for getting a replacement part from MTH to a do "proper" fix.

Just thinking out loud...... 

I had precisely the same problem with a RK VO100. The rollers were bottoming-out and lifting the truck. MTH makes pickups with smaller diameter rollers. Changed the pickup rollers, works like a champ now. And before you ask, no I don't remember the PN#, sorry. Hopefully Midge @ MTH can help.

Not sure about the vintage of your Lionel 072 switches. I don't want to start a rock throwing contest, but we used some 072 Lionel switches on the modular layout once, and they gave us fits. The root cause of your problem could be with the switch.

I think you will find that sooner or later some train item will have a problem with some piece of track. In your case it seems to be sooner rather than later. Not necessarily a fault of the train or the track, it just happens sometimes and usually someone here will have a fix or work around for the problem. The train makers can't test their items on all available track and the track makers can't test their track with all train items available. There are too many trains and tracks to test them all with each other. Just the way it works out sometimes. 

Junior,

Makes me wonder how MTH tests these engines (kinda like Microsoft testing software). Do they test over switches at all? If so, do they test using only MTH track/switches/etc. or do they test using a variety of manufacturers products.

Don't wonder, it's SOP for a manufacturer to test their engines only on their track, and to specify minimum curves the same way. It would be a very daunting and expensive task, indeed, for any manufacturer to test every one of their engines on the myriad of different track and switches available to today's hobbyist, even if restricted to only current production track and switches.

Regardless, the defect is in the track, not the engine. I have that v very same engine and it has no issues at all on my Gargraves track with several generations of switches from Ross, Gargraves, Curtis, and Right of Way.

I have the same engine and I have never had any problems with it going through Gargrave or ROSS switches.

Obviously you have a problem with your switches so in that case and you chose to take Mikes advice use a piece of 1 by 4 pine placed flat over the rails of the offending switch and tap lightly over the center rail. This block of wood should prevent any ding marks in the rail top.

RTR12 and Barry.....

Thanks for your thoughts.....guess my software background is showing; we wouldn't release any updates until that release was tested on all platforms. But I can see and understand your perspectives so I concede to your greater experience.

GG1....Thanks for tip, but I'm a bit hesitant to take a hammer to anything.

Gilly.....I like your suggestion. I will email MTH and see what they have to say. 

In the mean time, I'm still able to have "tons of fun" with the engines that do run well :-) !

Junior, did your circuit breaker on your brick trip when this happened? That looks like one heck of a spark occurring. Thank God no damage to the PS board.  

Gilly@N&W posted:

I had precisely the same problem with a RK VO100. The rollers were bottoming-out and lifting the truck. MTH makes pickups with smaller diameter rollers. Changed the pickup rollers, works like a champ now. And before you ask, no I don't remember the PN#, sorry. Hopefully Midge @ MTH can help.

Not sure about the vintage of your Lionel 072 switches. I don't want to start a rock throwing contest, but we used some 072 Lionel switches on the modular layout once, and they gave us fits. The root cause of your problem could be with the switch.

As Gilly noted, MTH does offer some pickups with smaller diameter rollers. I believe they are part #BD-0000097. These are single swing arm pickups. I needed these to replace the originals on an MTH GP9 when I found that the "fat" rollers were causing the drive wheels to raise off of the rails on some of my Super O switches.

Hi Dave!

Thanks for your concern. My circuit breaker did trip once the very first time I tried running the Y6b on my layout (which is under construction). I use PW ZWs to power my layout, 10A circuit breakers between the ZWs and the TIU along with Voltmeters and Ammeters to help diagnose which power block is having an issue. In addition, TVS diodes are installed on the outputs of the TIU channels.

While doing research (by running the engine at a really slow speed over the switches in order to diagnose what was causing the shorts) I would be primed to kill the power to the layout once the short occurred. It didn't take long to see what was going on.

Hi Rich!

Thanks so much for chiming in and providing the Part Number for the pickups. I emailed MTH yesterday but I'll check those out to make sure they're a good fit. I appreciate your willingness to help!

If you still want to contact MTH, I would suggest calling them on the phone. I think yo will have much better luck that way.

Hi Everyone! Thought I'd give you all an update on my Y6b shorting out on Lionel 072 tubular switches.

After emailing MTH describing my dilemma, I was contact my Midge who said she passed along my problem to The MTH Techs. I received an email from Midge a week or so later with a recommendation for replacing the original pickup rollers. The recommended roller replacement Part No. is BD-0000103 (see pic below)

Below is a pic of the original roller and replacement roller:

As you can see, the replacement (on the right) is quite a bit "skinnier" than the original. Everything else appears to be the same.

After replacing all 3 rollers, the Y6b made a few laps around the layout then stalled over a switch; where the engine dropped into start-up mode. This situation occurred several times.

Making a longer story short the grease port access screws where now shorting out over a switch! Groan......

DISCLAIMER!!! I by no means post the following as ANY kind of recommendation. PROCEED AT YOUR OWN RISK if you decide to modify your engine the way I did. I performed all the following "holding my breath"; hoping I wouldn't ruin my engine beyond repair!!!

I decided to VERY, VERY CAREFULLY file down the grease port screw heads (filed screw head on left)....BTW....there are 2.....

.....and VERY, VERY, VERY CAREFULLY grind down both grease port screw bosses....

Now the Y6b clears ALL my switches and runs like a champ. Yaaaaa!