MTH railking allegheny proto 3

Remove the shell and see if a wire came off of the rear motor.

The reason why the front dive wheels can spin VS the rear set is they are 2 motors, one for each drive block. Part 2, one has a tachometer (the rear set), one doesn't (the front one) BOTH get the same PWM power from the motor driver section.

More likely than not, the FIRST thing I would check is to ensure the linkages are not jammed being this is a steam engine. The most common failure is the eccentric crank screw loosening, causing the eccentric crank to rotate compared to the wheel resulting in a linkage jam, The linkage pivot point must be nearer to the wheel center to minimize the stroke length of the linkage. If it rotates outward- it trying to push and pull the valve gear links too far- often jamming the wheel.

https://ogrforum.ogaugerr.com/topic/78016146380926077

The first photo is a good example of the eccentric crank being correctly oriented with the pin point nearer the center of the wheel. The second photo is of a loosened one in the WRONG position likely jamming the linkage and wheel in the process.

@loco2124 posted:

Have recently been working on a Lionel Cab Forward and noticed that the eccentric cranks are not oriented correctly. (Prototypically)   They are not even the same between forward and rear sets of drivers.  I have also noticed that the expansion link on the forward set of drivers was backwards. I was able to remedy that but have not been able to change the orientation of the eccentric crank pins. They are oriented with 4 tabs and can only be changed in 90 degree increments which would throw them even further off.  I am supposing that the insert must be pressed out of the main driver and re-positioned but am unsure of the degree of success  I will have with this without damaging the wheel as I don't know if it is cemented in place or just pressed in.

Anyone encounter similar difficulties on this or other locomotives; Lionel or otherwise?  Any help would be appreciated.

Thanks.

FRONT SET FIREMAN'S SIDE

REAR SET FIREMEN'S SIDE

FWIW, I have the 2017 PS3 Virginian https://mthtrains.com/sites/de...ction/30st12601i.pdf

Page 35 of the manual shows the boiler shell screw mounting locations so you can attempt to spin the motors by hand and further examine the engine.

Also, see the MTH parts site breakdown for this engine.

https://www.mthpartsandsales.c...lists/263?type=lists

A tire can come off and jam the drive wheels, linkage as stated, motor lead as stated, or motor has gone bad.

Taking shell off and rotating motor fw of offending truck to see if it is jammed.  G

Finally got around to taking the shell off,  rear wheels turn when I turn the motor,  no wires seem to be loose,  it was working sporadically when I was testing on the track ,  possibly an electronic problem?

@Tim Tylenda posted:

Finally got around to taking the shell off,  rear wheels turn when I turn the motor,  no wires seem to be loose,  it was working sporadically when I was testing on the track ,  possibly an electronic problem?

Sorry, but I don't have enough information to even have an opinion on what the root cause is.

You need to post a video or far, far, far better description of the actual problem, your testing methodology, what the exact verbatim symptom is. On one hand, I understand sporadic can be a symptom, but that's not helping us help you.

BOTH motors are powered by the same circuit in the electronics. If one runs and one doesn't, sure, it could be electrical, it just as easily could be mechanical.

If one runs it can only me the wiring to the motor that doesn't, or that motor... from an electrical point.

Now I will say this, check the pins on the boiler board to ensure cold solder joint/short pin.

Since the motor seems to turn freely by hand, that probably rules out a mechanical bind.  G