Williams Scale Brass Big Boy Binding issues

First, examine the worm gear for excessive wear or broken teeth.  It happens, but not often on Williams' bronze gears.  The Williams gears are smaller than some, so it could happen.

Next, while the gearbox is off, rotate by hand to see if you can spot a rod hitting something.  Pay attention to side rods striking axles or parts of the driver, like the counterweight.  Crossheads can hit the forward crankpin cap.

If all that passes your inspection, it could be a driver out of quarter.  Then it is time to enlist the aid of a mechanic.  Joe Foehrkolb has an excellent reputation, and is very inexpensive, but has a backlog.

Bob,  Thanks.  I did remove the gear covers.  This is an unrun engine and gears are all nice.  I also disconnected front truck from rear so I could test each separately.  The driver wheel with gear does seem to move laterally with extra play.  I compared it to my Williams J and the J spacing was tighter, and the J runs extremely smoothly.

Wheels are quartered properly, Both truck sets where quartered the same (same side), so I rotated the front truck a quarter off so that both sets of drivers wouldn't match.  That seemed to improve it.  It runs well in forward, but it seems to want to jam in reverse.  It may be a combination of side rod sticking an touching drive wheel when it shifts to one side, but visually it doesn't seem like it should stop the motion.

One thing I do notice when it is jammed, the driver wheel set doesn't want to shift laterally like it can when un jammed, which makes me think some alignment issue in the gear box. 

Are those gear boxes suppose to have a lot of motion?  The rear is on the spring assembly like the J, but the front is not, because of the lower location as an articulate.   G

Moderators, why do you keep moving this to the Hi rail forum?  Most of the informative Brass Williams post are on the 3 rail scale forum.  That is why I posted it there in the first place.  I need technical help with a brass drive train, and most of the scale guys have that experience.  The only answer I received was when it was in the Scale forum.  G

Just my opinion, but you will most likely receive MANY more responses to your questions here on the 3-Rail Trains Forum, especially since your issues are NOT really related to "3-Rail SCALE Modeling".

I think the folks on THIS Forum have much more experience with the Williams products, even the scale size pieces, than any of the 3RS modelers.

Let me guess that it dioes not make any difference.  Most of us just glance at everything and comment when and where we feel like commenting.  On the other hand, most 3-railers do not get into these types of issues, since they seldom occur in RTR products.

A few 2- railers learn this stuff, because most early 2- rail was kit- built, and most used 2- rail steamers seem to have problems. 

I have spent literally hundreds of pleasurable and not-so-pleasurable hours fixing problems like yours.  When a driver locks up, whether it is from quarter issues, crankpin throw issues, or rod contact with something, it almost always gets immobilized laterally as well as rotationally.  So that is not your clue.

Quarter is checked by removing the driver, inserting it in a jig, and measuring where the crankpins are.  Crankpin throw should not be an issue on a Williams, but it too is measured with the driver off the model.

what you are most likely looking for is a counterweight striking a rod, or the forward crankpin cap striking the wrist pin - the bolt that holds the main rod to the crosshead.  Excessive side play in drivers causes these problems.

You have your choice - invest lots of time and become an expert, or contact Joe.  As far as I know, right now Joe is the only hobbyist willing to do this for a fee.  If I were to do it, I would have to charge more than the model is worth or do it for free.  I have more fun teaching in antique airplanes, so I stay clear of model train work for profit.  I do not mind sharing what I have learned.

As an afterthought - I have had brake shoe problems.  They are rare on 3-rail out-of-the-box models, but worth looking at.  On older 2- rail models they are a show stopper.

Thanks Bob.  I posted this originally here and there were no responses for 2 days.  Got your hit on the first day in the Scale section.  That is were I found most of the Williams Brass post with quality inputs when I was researching my N&W J purchase.

I am trying to learn,  I am just surprised how much lateral play the wheels have on this model.  The gear driven wheel can shift laterally and make contact with side rod.  The gear box moves with it.

On my J everything has tighter tolerances and the unit is very smooth runner.  I guess this is something to look at when purchasing a Brass Williams engine.  G

Well, there is your answer.  Make "C" washers that will snap over the axle, restricting side play.  Make the opening just smaller than the axle, and they will snap in place and stay there.

If the rod is contacting the driver, the sharp edge of the counterweight - where its chord joins the rim - is probably jabbing the rod like a hook.  Very common.