Linkage/Timing

Sounds like you pulled the drivers. They need to be offset exactly 90 degrees between each side or the rods will bind. There are special tools which help press the drivers back on at exactly the right angle, which I'm sure others can detail further. You probably can get it close enough to 90 degrees to work okay without special tools.

Both wheels on each side need to be placed on the axles EXACTLY in the equivalent rotary position. Do one side at a time. Put the rod (that's what it's called) onto one wheel, then rotate its adjacent other wheel so that its rod opening is EXACTLY in the same clock position. Then they will not bind.

On a real steam locomotive, the drive wheels are arranged on the axles so that a wheel on one end of the axle is exactly 90 degrees out of phase with the wheel on the other end of the axle.  This scheme is used to prevent a standing locomotive from being stalled due to the cylinders (on the left and right sides) both being at top- or bottom-dead center.  When the wheels are "quartered" at least one cylinder will NOT be at top or bottom dead center.  On toy trains, the cylinders are just there for looks, the drive rods just float around in the fake cylinders, and there's never a chance of their becoming stalled. The motive power comes from the axles to the wheels, not from the cylinders to the wheels.

It looks prototypical on a toy to arrange the drivers in a "quartered" arrangement, but it's not relevant to the operation of the locomotive.

Agree with all the above. Let's assume ( very tricky word) you mounted the wheels correctly; if the motor is a type 8 in that the armature can be easily removed, it's possible that in mounting the wheels you got one set (front or back) off sync by a tooth or two, that's relatively easy to fix by pulling the armature, rotate one set to correct tooth sync. The case may be the same with different motor types such as type 7 just a bit more involved because you can't remove the armature. Then you'll have to spread one set of wheels enough to rotate to the correct tooth and press back together. All the above is for double intermediate geared motors and definitely check the rod mounting as you go.

@prdmb1957 posted:

I have been working on a Lionel #257 steam engine.    In addition to rewiring the motor,  I had to replace the wheels which meant removing the eccentric bar and cross bar(? the bar that is attached to both wheels).  This is my first attempt at putting the cross bar back on the wheels and I am having a heck of time making it work as the bar does not make a complete revolution - ultimately binding up the wheels.  What should the position of the wheels be in when reattaching the cross bar?  Thanks for helping out a newbie to repair work!

The rod that connects the wheels is called the side rod.  The rod from the main driver to the crosshead is called the main rod.

Thanks, all for your responses.  After a couple of tries I got it together and it runs great!