Just some notes in passing, about gears---
The motors are small and of limited torque at the motor shaft. Their power comes from the high speed at which they can turn. So a lot of geared=down reduction to reduce shaft speed (rpm) and increase torque. In postwar items with the larger open frame motors the shaft torque was greater, and the gear reductions less. With less reduction, spur gears could be seen, sometimes in two reductions through spur gears. Worm gears were the gift of the Italians (NYC Hudson 700E), with 3 starts on the worm, in postwar typically matched with a helical gear wheel where the the teeth run across the gear face at about 30 degrees to the axle carrying the gear. This arrangement would not lock up abruptly, but it did have a braking effect.
One important thing to know is that the use of a helical gear driven by a worm shaft is an approximation to a true worm wheel (not to be confused with the track wheel even when mounted on the same axle). At first, the contact is point contact and the wear rate is high. Ideally, the helical gear will wear or displace to have a half-moon depression centered on each tooth between the gear sides and maximum at top of tooth. Generally, this ideal is best accomplished by having a steel worm shaft that is ground and polished, while the worm wheel is of a softer material such as brass {in toys}. The later postwar worms are have die-formed teeth in softer steel, and eventually these dies became quite worn (I believe this was the later method, from a visual comparison of the 50th Anniversary Lionel 027 UP diesels, to later GP7/9s and O-gauge F3s). This situation improved markedly before the introduction of GP7s with TMCC (2380s) in 1995--I would guess new dies for the worms may have been obtained about 1990; I lack representative engines from that period as I decided to get parts instead, to replace zinc wheels, plastic gears, and lack of Magnetraction and 2nd motors .
Unfortunately in 1954, the standard gear tooth pressure angle changed from 14-1/2 degrees to 20 degrees, for metal gears. (Plans once showed gear teeth, and a 4 on 1 gear face was quicker to draw.) Unfortunately, plastic gears were kept at 20 degrees, while they often required 25 or even 30 degree pressure angles to avoid tooth breakage. So my first retrofit resulted in a hot Pullmor, and a hotter truck under it, from running the side gear sets between axles with non-matching geared track wheels. Moral: One has to be sure of what one ia looking at when troubleshooting, and it its really hard to see with small mechanisms, although not impossible.
So, on the matter of running in, keep in mind that a worm gear set is really two gear sets, one operating in each direction of travel of the engine, and each needs to be broken in (forming the little half-moon wear spots). Obviously, running-in without much lubrication goes faster, but has to be carefully watched. My advice is to avoid using abrasive paste to help--this ends badly. It is also immediately to be noticed that end play in the shaft that carries the worm wheel will shift the wear spot; this can be a life-shortening problem if that shaft is also the axle for track wheels. It can be difficult to add spacers onto the axle, between wheel inside face and truck bearing face. There is an E-circlet size that can be sprung over a postwar GG-1 axle with this problem. but if a thinner shim is needed, I think on the O-gauge engine on tubular track, a back-to-back as little as 1.07" between small (like diesel) driving wheels, by pressing the wheels further on, is the better solution. With the F3s, this keeps the flanges off the switch frog points. The 1.10" back-to-back seen on so many modern F3s and Geeps comes, I think, from the only comment on this in a Greenberg reprint of 1950's or so service manual pages, for the NW-2 switcher 6220, that dealers make a gauge of 1.10" for it ( an 027 engine (4-digit #, vs 622), 027 track having .03" wider gauge than O track). Steam drivers are different (larger) and so their flanges are held against the inner rail by the guard rail, where it has large clearance preventing it from holding the smaller diesel wheels off the frog point. An 1.10" back-to-back is correct for the drivers on steamers; I assume pilot wheels (and possibly trailing truck) wheels have the 1.07" value that standard formulas indicate.
There are standard formulas for the heaviness of grease required in gear sets; application of these formulas to something like crossed helical gears (IIRC), which approximate a worm gear set, have suggested to me a required value of about 600 (sorry, forgot the system of units here, but only about two of the several system are used in sales literature, with fairly different numbers). Lionel postwar practice (see following paragraph) may have influenced me. In any case, the concern over this now typical reduction indicates there is a problem with present lubrication. Possibly the Lion Drive, where only one axle in the motor truck was driven, in diesels, was influenced by this problem.
Postwar Lionel practice appears to have extended the use of these formulas into small mechanisms-- the high numbers that result are due to the high speeds at which such operate in model trains as heavy as O-gauge. In evidence, I refer to the 1946 626 steamer, which had single motor, but a worm gear on each of the two (end) driving axles, and the follow-on 1948 2333 F-3 NYC & ATSF diesel engines, where the motorized locomotive had 2 horizontal motors, 4 driving axles, and 4 worm gears, again one for each axle. This would indicate that the fish-oil grease must have had a rating of at least 300 (typical of the upper reach of automotive greases, where a few special purpose greases might get to 350 (bicycle chains and such). The great advantage of the fish-oil is its adherence, of course, which is superior in that to modern materials (IMHO). I'm thinking of going with the fish in my limited work, although I'll stick with what comes in factory engines, in case they found something. (Fifty years ago I did locate a Texaco grease that looked like it could replace the tar often used in the last gear set on bascule bridge spans similar to that on the I-895 beltway (Baltimore MD), which were 155-feet long over trunnions and about 44-feet wide (two 12-foot lanes plus full outer shoulder, and inner shoulder wide enough for a car). Those gear teeth were 5" diametrical pitch (that is, on the pitch line, a tooth, valley and small clearance would take up 5 pi inches, making a tooth about 1.57 x 5" thick at the pitch line (about 8" at mid-depth.)
For porous sleeve bearings on axles, I would recommend a 30-weight (SAE weight but don't use automotive engine oil because its additives are harmful) white turbine oil. This is fairly easy to find; it is used in machinery in contact with food and doesn't leave stains. One may be able to use 30-weight 3-in-1 oil, but I prefer the other. These bearings may come in a form already lubricated, but of course the instructions always say "oil." As I believe such bearings would be outside sourced, they would logically contain turbine oil.
I have a recent Bipolar and will take a closer look at it. I got it because my father left Belvoir for Japan during the Korean war. I was 12 and still remember standing on the platform in Baltimore as the train left. Eventually he reached the ;Milwaukee Road and traveled behind once of these. He sent back its timetable, which I still have. But I remember all that because I was never again to spend a full year with all of us at home--48 shots but never got to Japan (well prepared for the CoVid shot with notice 6pm night before--bring it on, I cared not which version and never felt it. --Frank
