Janis... Perhaps they are pressed too far into the frame allowing the extra amount of play in the wheel set?
More likely, they are worn. The correct repair is to replace or reset the bushings, but the shim in the gear well works nicely. It saves having to pull the back two driver axles and their wheels.
Rob
A little info. on your Lionel #726, 'O' Gauge
http://www.postwarlionel.com/cgi-bin/postwar?ITEM=726
Ralph
I have a 726 with the same issue. I was thinking about using a shim, but was somewhat hesitant until I read this forum. I tried it and the engine now runs like a rocket, so much so that I laid her on her side in an 072 curve. Impressive!
The worm wheel axle had more play in it than the other axles. I noticed that the axle bushings on the other wheel sets protrude a little from the engine frame, but that the bushings on the worm wheel axle do not. Perhaps they are pressed too far into the frame allowing the extra amount of play in the wheel set? In an event, the old girl is as good as ever.
Glad to hear you got it working. Instead of the spacer shim you could try pressing the worm wheel more to the left therefore offsetting the worms natural tendency to "screw" the wheel to the right. I've made myself a jig for setting up the worm/axle relationship for when I restore F3 diesels and it takes all the guesswork out of the assembly.
Jim
Repaired, Final Update on this issue:
Proceeded to shim front and rear of motor, 0.01" this way and that way up to 0.04", no go. By the way, 0.05" is the highest I could go before I was totally un-meshed.
Pulled all shims out and made up a C-type clip and inserted this on the right side of the worm wheel and over the axel. Placed the Berk on the track gave it power and BINGO!! Off she went, too much power and nearly derailed on the first curve.
My problem here was side to side action of the axel moving the worm wheel to the far right of the loco and binding in the grease pit. Therefore using a 3/16" polished washer cut with my dremel tool into a C-Clip type spacer of 0.04" thickness set the worm gear in the center and has not failed all day!! I shall run this unit with the added modification and will tear down in approximately 2 weeks to investigate any excessive wear to worm wheel. No problems negotiating around curves, runs great!!
I would like to thank all that stopped by and helped in this matter. Jogging my mind is appreciated. I would also like to say, that this 726 Berk 2-8-4 has another generation of my family to show off to. Shoot, I guess I'll need to start on 2426w tender now.
As my grandson would say, "Choo-Choo PaPa" Later gents!!
Starting in 1947 Lionel changed to a 25 tooth worm wheel as oppsed to a 23 tooth worm wheel in the 1946 version, to increase the gear ratio numerically. If you have the 25 tooth worm wheel you will need to shim your motor up to make up for the larger wheel. Also Lionel changed the front thrust bearing arrangement, counterboring the front of the motor housing to allow larger diameter thrust washers. .302 inch to .365 inch diameter. Check what version you actually have. The thing with 60 year old locos is that unless you're the original owner, you don't know who's done what to the thing. Hope this helps.
Update - Day Three:
Pinion gear looks to be good, very little wear.
I have the gears meshing without a spacer to lift the motor. I can manually rotate the wheels freely in either direction. I may have not tightened the motor correctly in previous posts. I evenly tighten now and all seems better. While rotating wheels manually, the worm wheel/axel is almost self-centering, no side to side action/travel. BUT when placed on the track and placed in the forward direction utilizing the motor, I see torque on the worm wheel/axel and it immediately slams to the right of the engine frame and then binds. Placing the unit in reverse, the worm wheel centers and runs as though it was new. I shall experiment with a spacer between the right frame and worm wheel, manually centering the worm wheel and see if this cures my problem. I'm expecting that there will be a reaction to this spacer in axel freeplay while taking a curve on the track, we shall see...
Comparison measurements of my reconditioned armature and the original:
Origianl total shaft length from bake-o-lite nipple to end of shaft = ~2.35"
Reconditioned total shaft length from bake-o-lite nipple to end of shaft = ~2.30" This is too short for this motor. It will fit if, one set of ball bearings is not installed. Bearing diameter = ~0.06"
If both sets of bearings are installed, forward and rear thrust,.. I cannot install the C-clip, the groove is now inside the housing. My observation of the reconditioned armature is, the bakeolite nipple onto the shaft under the winding, is longer then the above original. Being short by ~0.05" sounds small, but it will not work.
Back to the table and try something new,.. The will saga continue....
Update: Well,.. I had purchased a reconditioned armature and was using it when I posted the above message.., but I ended up replacing my armature with the original after a little clean up work. I will be posting another message soon, on armature machining and what tolerances there should be. The reconditioned armature does measure out compared to the original. Makes me wonder if I have the correct motor in this unit?? Or someone got a batch of bogus armatures...
I now have the gears meshing, somewhat.. I installed the motor and with some jumper wires and alligator clips, this Berk ran like a champ,...in reverse! Oh boy, I almost wet myself,.. THEN,..When placed it in forward direction, the e-unit hummed loudly and it jerked and jumped badly and finaly stopped with the e-unit humming. Placed it back in reverse and it took off as those it was new. I think I still thing I have meshing issue here, binds in the forward direction only. I have some thrust bearing washers that I will use as shim material.
If anyone has had this same problem, give me a hollar,.. otherwise I'm back to the table with my calipers and shims. I'll post another message with measurements between 2 armatures, maybe I can ID motor vs armature??
Bob, You got me thinking, all thrust washers are in.
I FORGOT TO PUT THE BALL BEARINGS IN THE REAR THRUST. I did the front and got anxious to get things together late last night. I Should have waited till today to assemble. I woke up at 3am thinking about this and to the life of me,...I forgot.
Thank you sir.
Bob Nelson
1948, 726 Berkshire 2-8-4, Lionel Precision Motor #671M-1:
I have almost completed the restoration of my 726. Before starting the soldering process, I have installed the motor and have come across a concern. My armature shaft appears meshed with the worm drive gear and when manually rotating the wheels in the reverse direction, everything seems smooth and very well fit. BUT, when trying to rotate the wheels manually in the forward direction,.. it locks up. I want to say it immediatley binds.
Removing the motor, the armature rotates freely and smooth, and all wheels/side rods function great.
I was wondering if this characteristic of a worm gear assembly, OR, have I missed something??
Your help would be appreciated.
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