Postwar Lionel 746

Though I've never had the pleasure of owning a #746, I do know that there are Lionel motors that, having been used almost exclusively in one direction, will perform differently when running backward or the reverse, as in a 2-motor "A" unit that has only ever been used on the point, will not run exactly the same when used as the 2nd "A" in the "dummy" unit position.

It's my belief that it's good to run them both directions, but as in your case and many steamers, it's hardly a joyous experience, so running in reverse is usually only to pick up cars. Also, make sure you use quality grease on the gearing right under the motor. When that gets dry, you can get unpleasant squeaking and even seizing up. PS: If your grease is old and you don't want to replace it, you can use a drop or 3 of Pennzoil 5-20, which will "unfreeze" in a few minutes' run time the old grease. But it should be new, good grease and Red Devil is hard to beat...

May be time to split the E-Unit apart and look around for dirty, bent, scorched fingers, worn, dirty drum. Remove side rods for potential binding, and run and see if that makes any difference. Check if any drive wheels are binding or loose on their axles. Is there any difference in running on a straight section vs curves? Check all wheels for free spinning, no binding and excessive bearing wear.

@gandydancer1950 Is the 746 new to you, or have you had it a while and this is a new problem?

I am not exactly sure, but I think the 746 and 736 have similar chassis / motor / mounting.  With the 736, there are a couple of thrust washers that keep the worm gear in proper position to engage the axel gear in either direction.  If one or more are missing, it will tend to bind.  Also, there can be a few washer shims that were sometimes inserted under the motor to align the mounting for proper gear mesh.  Just some food for thought...

@ADCX Rob posted:

The axle bushings on the powered axle are worn, shifting the worm wheel off center from the worm and the driver into the chassis in forward.

The alignment is all good when it's in reverse, so it should run better backwards(after proper lubrication).

The right rear axle bushing is always the one that wears out first(from forward operation), pushing the axle left, the right rear wheel into the frame, and the worm wheel off center.

Of course, the factory fix is to replace the bushing, which requires pulling the 4 rear wheels(two flanged & 2 blind), pressing out the axle from the worm wheel(gear) and the frame, pressing out and replacing the worn bushing(s), and then pressing the axle back in to the chassis and worm wheel, and quartering & pressing the 4 wheels back on.

For an easy fix that will last a long time, use one(or two or as needed) 671M-22 clips/retaining rings and snap them on to the drive axle to the left of the worm wheel. You want to have between half to the full width of a 671M-22 clip of end play in the axle for best performance. Keep the entire gearbox & axle lubed well with a synthetic HP grease(Lucas Red 'N' Tacky #2, eg.).

If you can source some clips with the same inner diameter as the 671M-22, but larger outer diameter, that would be beneficial. Another good tip I heard was to use an appropriate number of plastic bread closure clips(cut to be round & split to go over the axle) instead of the 671M-22. Very little friction with that method and they too slip right over the axle and stay on.

ALSO, it is also very important on these & turbine/Berk locomotives to make sure the side rods are not excessively worn and that they are oiled with a good synthetic. They transmit power from the geared axle to the other three.

Rob if I am understanding you correctly installing a retaining clip on the driver axle circled in red may help? Funny thing is this engine was hardly ran, shows no signs of wear ANYWHERE but was stored in a garage for nearly 60 years. The armature shaft was frozen in the housing preventing the armature from turning......at all. I was finally able to gently tap it out. I replaced all thrust bearings and washers, cleaned the commutator face and slots, filled the gearbox with Red N Tacky. She runs okay but not the way she should. when bench tested on blocks it clearly runs smoother and faster in reverse. I was starting to think perhaps I needed to shim the motor a tad before I sent out my SOS to the forum. If you can clarify your answer to me I would greatly appreciate it. Happy New Year!

Rob is spot on, ....what’s happening is the wheel is acting like a very effective brake shoe, .....slowing down forward operation, ....either one of his suggestions, the E clip, or the bread bag clip tricks are extremely effective repair solutions, and yield instant results,....this is a proven repair....

Pat

@harmonyards posted:

Rob is spot on, ....what’s happening is the wheel is acting like a very effective brake shoe, .....slowing down forward operation, ....either one of his suggestions, the E clip, or the bread bag clip tricks are extremely effective repair solutions, and yield instant results,....this is a proven repair....

Pat

Thank you!

@gandydancer1950 posted:

Rob if I am understanding you correctly installing a retaining clip on the driver axle circled in red may help?

Although I put the clips inside  the chassis opposite the rubbing wheel - between the worm wheel and the frame, slathered in grease. You can put the clip(s) on the outside to test, but you don't want to leave them there.

@ADCX Rob posted:

Although I put the clips inside  the chassis opposite the rubbing wheel - between the worm wheel and the frame, slathered in grease. You can put the clip(s) on the outside to test, but you don't want to leave them there.

Thanks Rob not sure if this is the problem. Upon inspection under good light I can see the axle bearings on each side....as a matter of fact I can see all 8 axle bearings unlike your photograph.. My photos do not reflect well what I can see. Any thoughts?

It has to be the mesh/backlash at the worm, then. Are the side rods all oiled with synthetic? Does a visual inspection show that all wheels are in quarter?

You

@gandydancer1950 posted:

Rob if I am understanding you correctly installing a retaining clip on the driver axle circled in red may help? Funny thing is this engine was hardly ran, shows no signs of wear ANYWHERE but was stored in a garage for nearly 60 years. The armature shaft was frozen in the housing preventing the armature from turning......at all. I was finally able to gently tap it out. I replaced all thrust bearings and washers, cleaned the commutator face and slots, filled the gearbox with Red N Tacky. She runs okay but not the way she should. when bench tested on blocks it clearly runs smoother and faster in reverse. I was starting to think perhaps I needed to shim the motor a tad before I sent out my SOS to the forum. If you can clarify your answer to me I would greatly appreciate it. Happy New Year!

You state you replaced the Thrust Bearings and washers were they all the same thickness as that motor is shimmied and if you changed that shimmed thickness or bearing thickness you may have created your problem.

Also to add to Rick and Rob’s assessment, sometimes Lionel, or a Lionel service dept. put shims on the motor mount locating pins to adjust gear mesh, ....did you see any when you worked on it, or did any get moved, or there might have been none at all,.....I’m sure Rob or Rick could give you the part no. for the shims, ....my old crusty postwar service manuals are buried under a mountain of books, ....😉

Pat

No shims were found but I do need the part number.

@ADCX Rob posted:

It has to be the mesh/backlash at the worm, then. Are the side rods all oiled with synthetic? Does a visual inspection show that all wheels are in quarter?

Yes Rob I lubed all the side rods and they are in quarter. Can I loosen the mtg bolts slightly while running in forward to see if I can move the motor slightly as if shimmed to possibly get a better result? Wouldn't that indicate that shims may be needed. Would you have the part number? Sorry for all the questions but this is a beautiful locomotive.

Loosening the motor might give some indication(s).

@ADCX Rob posted:

Loosening the motor might give some indication(s).

Thank you Rob, you've been a great help.

I also had the same problem. I change one of the eccentric crank screws. It was bent, and now it runs great in both directions.

Anybody know a source for those washers?

You could take your caliper and go into a good hardware store and hunt.  All that matters, IMO, is that the thickness is appropriate and that it fits over the little locating stud that sticks up for the motor, If you can get a selection of Lionel produced shims, all the better.

From experience as a former Service Station back in the 80s-90s, all of the above comments made by the earlier posters apply to  any of the 4-8-4 engines Lionel produced as they were all the same chassis/motor  (736).

If ,for example, you put one of the SP Daylights under my Christmas tree, before I ever put it on the track I would take the shell off and look at the gear situation and proceed accordingly.

The shims were sometimes not there, or the screws not tightened, or no grease from the factory.  Sometimes the worm gear was quickly ruined by the unknowing owner in a worst case scenario. The gear on the axle is only brass, so it comes out a loser first.  

In any event, the goal is always the same: reach a happy medium between binding and poor gear engagement.

John