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MTH Big Boy 4014 Binding


sse1478
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Hello everyone,

I just took delivery of my Big Boy last week and it will occasionally bind and stop moving. The locomotive still has power and I can hear the motors trying to move the engine.

This will randomly occur on perfectly straight track, when entering a curve, and when exiting a curve.

This only occurs when going forwards

I can usually back the locomotive out of the bind but sometimes it is completely jammed.

The locomotive has a lot of play on the tack and sometimes I can free the bind by moving it side to side with my hands.

I followed the lubricating instructions and have less than 0.5 hours of run time.

I would like to avoid boxing it up and taking it back to the shop for service.  

Any help would be greatly appreciated.

Spencer

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Have you identified which engine set is binding?  Take the engine off the track and put on work bench and make sure ever single rod screw is screwed into the driver all the way and snugly. (Focus attention on the #1 and #2 driver rod screws on both sides of the engine).  If you have to tighten them be careful to not over-tighten.  

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Ray,

Thank you for the quick response! I think it is the second set. The #1 and #2 driver axles seem to have a lot of play (both up and down and side to side) I assume this is to accommodate the R3 curves. When the engine navigates an R3 curve the #1 driver axle is not always flush with the rail and rides on the flange. I am not sure if this is normal. How much play should there be between the linkage and the drives on properly tightened rod screws?

Spencer 

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The up and down travel is part of the drivers independent sprung suspension.  The side to side play is normal and like you said is what allows it to take such tight curves.  R3 equates to an 8ft diameter which the absolute minimum the engine can possible navigate .  One thing I have seen is where the curves aren't completely uniform where some parts are wider diam and some are tighter diam so that can come into play as well.  That said, running on an 8ft curve is still very tight for that engine regardless of what the published minimum is so the#1 axle not being flush in the curve may be part of a symptom of that.

 

I don't have a measurement on linkage spacing to provide, when the rod screws are tightened down they will all appear uniform.  If you have one loose you will know it.

 

 

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I understand 8ft diameter is not ideal but I do not have the room for anything larger on my indoor layout. I am hoping good track work with no grades will provide reliable operation. I will tighten all rod screws this evening after work and report my results. 

 

Just to make sure we are on the same page with terminology, driver axle #1 (of set 2) would be the one closest to the front of the engine on the second set. 

 

Also, I noticed the eccentric linkage on the second set can move about an inch side to side while the ones on the first set have very little side to side movement. 

 

Lastly, what is the best way to pick up the locomotive? I put 1 hand over the cab and the other under the boiler and just let the all the wheel sets dangle. 

 

Thank you again for all your help!

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Sure thing.

 

Yes that's correct, #1 driver is the first axle set from the front of the engine on each engine set.  So front engine set has drivers #1 thru 4 and the rear engine set has drivers #1 thru 4.  Axles #1 and 2 are what I would focus on but make sure all the rod screws are tight.  Again, be VERY careful and do not over tighten or your risk snapping one off.

 

On picking the engine up I do it two way depending on the situation and where I'm positioned... One is like you said, to lift from under the front of the boiler and then other hand lifting up on inside-top of the cab.  Another way is to rock the engine to one side by grabbing/pushing via the cab then get your fingers under the front engine set and support the front engine set from underneath.

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I tightened all of the rod screws (1/4" hex if anyone was wondering) on both sets. None of the screws were loose and at most a 1/4 turn was applied. There is still about 1/16" of play with the linkage which I assume is to accommodate the curves. The binding is definitively occurring on the #1 axle of the second set and I do not see any visual obstruction caused by the linkage (I can only observe 1 side because my layout runs along a wall). The binding was freed by moving the locomotive side to side while still on the track. The binding occurred twice in a similar location on straight, level track about 6ft from any curve.

20170517_223001048_iOS.jpg

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I recommend trying to shim the #1 axle on the rear engine set as noted here:  http://www.rayman4449.com/MTH_Big_Boy_mods.htm#Slider_shoes_causing_shorts_on_Cross-overs  (see section about shimming axles)

 

Try that, if still does not work try shimming axle #2 but it sounds like #1.  I can't see the engine in operation so cant tell if there is anything else going on.  I test all my engines before shipping to catch as many issues as possible before the customer gets them.

 

 

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Ray,

 

The problem is solved! Thank you so much for your assistance!

 

I ended up shimming axles #1 and #2 of the second set with 0.25" ID 0.5" OD 0.035" thick nylon washers obtained at Lowes. My local HD no longer stocks a a suitable washer. 1 washer was used on each side of the frame for a total of 2 washers per axle. These washers are about half the thickness of the ones pictured on your tutorial and leave enough play to navigate the R3 curves. I did not shim the first drive set. The underlying problem appeared to be the rod screws on #1 and #2 axles interfering with the piston linkage.

 

I am considering your fuse mod and have 2 questions. 1. Was the underlying issue fixed with this new model? 2. Will it void my warranty?

20170518_024811902_iOS.jpg

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Very good to hear :)

 

On the fuses, the new models are made to be much more durable but I am still adding them for my customers as a precaution.  I would discourage customers from modifying their new engines that are under the warranty period.  For now if you are running the engine by itself i would run with a 3, 4 or 5amp fuse as the fuse between the power supply and the layout as the precaution.  After the year is up and you want to add them to the engine then by all means do so.

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For sure have a fuse between the power supply and the track. If your loco binds in a switch for a short, the fuse on the power supply will protect the engine circuitry. Happened to me, so it's an easy precaution.

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