1941 City of Los Angeles

[ScaleCraft]

Have you actually run one of those Adams gearbox units? The older-than-me-timers told me they were coffee grinders.

[bob turner]

Yes. I prefer them to CLW, and I prefer CLW to All Nation. The gears can wear out, and then we have a problem. Turns out that not all Adams gearboxes used the same gears, or even the same spacing from worm shaft to axle.

For absolute smoothness using worm gears, you need rigidity, and these things have rigidity in spades.

Jay's solution eliminates worm gear noise - it might be the wave of the future.

[E7]

One thing: From the factory, this unit probably had a selenium rectifier to reverse the field, but this one arrived with no rectifier (and no manual switch, and no sign that a manual switch was ever installed). Actually, if you are running a passenger train round-and-round (which I do), then having no reverse may not matter. I will come back to this topic in some future post as I consider how to wire the AB set for best operation. Jim

Greetings Jim,

I'm not any great electrician by any stretch, but I thought a rectifier was a device used to convert AC to DC. Not trying to put you on the spot here, but trying to learn something.

Regards,
Rich

[R.K. Maroon]

No problem, Rich -- We had a whole thread on this once, and while it is a darn shame that we lost all those old threads, I still have the diagrams on Photobucket. Wayne ginned up some too so he may wish to comment.

The diode works to make sure that the polarity of the field is always the same -- just like a permanent magnet. I will post the diagrams and hope they are self explanatory. First, from the 1940 Walthers catalog, showing an old (and my favorite) selenium rectifier:



Now with arrows showing the internal diodes:



Track voltage at one polarity (note direction of current flow in field and armature):



And now with track polarity reversed (armature reverses but field does not):



Hope that helps
Jim

[ScaleCraft]

Greetings Jim,

I'm not any great electrician by any stretch, but I thought a rectifier was a device used to convert AC to DC. Not trying to put you on the spot here, but trying to learn something.

Regards,
Rich

Field wound motors are also "universal" motors. Work on any type of current (to wit: most starter motors, the heater and wiper motor in my Jag). Good thing is, you convert a vehicle from positive to negative ground, the motor runs the same direction.
You apply DC to a universal motor, the field is the same current flow as the armature..one direction. Reverse power, they again are the same direction. Rectify one (and I have) and not the other, when you change direction, the power stays same direction in the rectified portion, while the other reverses..and the motor goes the other way!

[webenda]

Wayne ginned up some too so he may wish to comment.

Jim

I used a Radio Shack 25 amp bridge rectifier. Only useful for those not interested in authentic restoration. Price is going up and up at Radio Shack but still $2.50 at All Electronics.


Radio Shack Catalog #: 55052185 :: $5.70
All Electronics CAT# FWB-252 :: $2.50

[bob turner]

Are you telling me these selenium things have value? I just tossed one last week!

You are all correct. The bridge is used to convert AC to DC somewhere, and if you have a field wound motor, it is used to keep current as Jim says.

So for Lionel, with DC motors, you need a bridge in each locomotive. For most of us, you need one at the transformer. Either place, the new $2.50 deals are perfect.

Finally, for the old Lobaugh or K&D motors, you need a bridge at the transformer and another - serving a slightly different function - at the locomotive.

I keep that schematic on my test transformer, so I don't have to think so hard each time I wire up a series-wound motor.

[R.K. Maroon]

Bob, I would not say that a selenium rectifier is valuable, though we could put one up on eBay to test that theory. I take all that come my way and use them if I am restoring a model with a wound-field motor. I currently have a stash of about ten, including five or so that are brand new, so I will not lose sleep over the fact that you threw one out (I hope).

To continue the story of the COLA E6s: The arrival of that ACL E6 with the complete drive gave me two complete original drives. The light still didn't just click on though, and here is why: While the E6A had a solid cast-bronze floor designed to accept a drive, I had it in my mind that the B-unit was just a shell with dummy trucks, similar to this Adams FT. The Adams and Son lettering is on the underside of the roof -- the trucks attach to bolsters -- here pieces of wood -- secured between the cast sides. There is no floor:



It was not a bad assumption, as the Adams E7Bs I have are all cast aluminum and unpowered with no floor, and I thought the E6B was the same. But it turns out that the E6B has a floor in it just like the E6A:



Well, not just like the E6A, as this floor is aluminum, but the critical thing is that the floor is designed to accept a drive. WOO-HOO! I'm in business now. Still, I find it an interesting compromise: Make the B-unit aluminum so that if the modeler chooses to leave it a dummy then the weight is minimized, but put the hooks in for a drive so that option is available too. Hmmm...works for me. By the way, note the many odd holes and add-on bracket in the middle of the drive opening. This is the way you generally see these old models -- that is, they have been worked on and modified, often multiple times.

So finally a plan came into focus: Outfit both units with an original drive. That made it easy to get started. The first step was to disassemble, clean, and inspect all the drives I have to see what I was up against. Full inspection report next.

Jim

[R.K. Maroon]

So here is a review of the drive pieces going into the COLA E6 pair. First, two original wound-field motors:



I think these are K&D #3. They both drew about 2.5 amps just to turn when I got them. I completely disassembled them, cleaned them up, oiled and reassembled. No load current of both right at one amp after cleaning. Both run very smooth too. Note that I was careful in cleaning these, so as not to damage the glyptol insulation on the windings or otherwise ruin the cardstock separators. Brushed the dust off them with a toothbrush, and then used a cotton swab and alcohol to get all the old grease and caked-on brush residue off. I was pleased with how they cleaned up.

Next, here are four gear towers. The two with only one shaft showing (upper left, lower right) are the two that will be used -- the motor shaft is long enough to go all the way through the case:



These towers contain two gears, a 40-tooth fiber gear and a 48-tooth bronze gear:



Interestingly, three of the towers were set up for speed, with the 48-tooth gear on the motor. Only one was set up with the 40-tooth on the motor. I will install both in the lower-ratio setup -- I do not run at Lionel speeds.

I have six truck gearboxes available for this project, four that came with the units and the two from the ACL unit. The all have a removable bottom cover (not all Adams do):



Let's see how many good worm sets I have. Here is the first pair:



Eh, not so good. Two good axle worm gears and no worms. No worm shafts either. Second pair:



Two worm shafts with all worms intact, five good axle gears. Third pair:



Two worm shafts with all worms intact, but only three good axle gears. So I have four complete and usable worm shafts, twelve worms, but only ten axle worm gears. I will look around to see if by chance I have any lurking, but I don't think I do. These axle gears are smaller in diameter then recommended for the pitch, so they are not (and should not) be common.

Jim

[bob turner]

When I stop flying every single day, I shall design a gearbox like these to fit the CLW gears. I will build them up, as opposed to machining castings.

[R.K. Maroon]

Bob, I haven't check CLW gears, but the shaft separation distance on these gearcases is the same (as best I can measure with calipers) as the All Nation drive. The gear ratio is different though so I would have to replace all the gears, and that would mean cannibalizing a lot of otherwise intact All Nation drives. I may do it though if these don't last very long, though I would search for a better way first.

I know what I am describing is not exactly what you are talking about, but it is a close cousin.

Jim

[Jay Criswell]

.....or a ****** stepchild!!

[R.K. Maroon]

Here's a bit more about those original gears:

The axle worm gears have fifteen teeth and the worm is a double, so the truck gear ratio is 7.5 to one. That's pretty high. With tower set up for speed (6:5) the overall ratio is 6.25:1, which is REAL high. With the tower gears reversed the ratio is 9:1. That's a big difference, and much better, but still higher than I like. There is another thing I could look at: It seems that 40" is the standard wheel size for diesels, but I believe these early E-units had 36" wheels. I haven't measured these yet, but if they are 40" I could consider going to 36". That's a ten-percent change, which would be like getting an effective 10:1 ratio overall. If I were to make that change it would be more to lower stresses in the gears than to slow down the speed. That would nice, but I think that it's a bit over the top. I would get a better lift on the gears by simply finding two more axle gears. But if I don't I will still have ten, which is better than the six I would get if I didn't power the B-unit. Besides, I could go with ten now and add two more later if I find them.

Note also that there is some other work here. Check out the misalignment in the gear on in lower middle:



That one will need to be reset. And then check out the wear on this axle:



That is a big surprise to me. I would have though the steel axle would essentially never wear and all the wear would be in the bronze. Look how wrong you can be! Interestingly, the gear is still good (go figure that). I need that gear so I'll have to sweat it off and use it as a replacement on an axle with a worn gear.

Than brings up the question of shaft runout. All of the axles and all of the worm shafts have some amount of play in them. Bob has suggested a repair procedure of coating the bronze journal with solder and reaming. I can do that, but I wonder if I need to. Any thoughts out there on how much runout is acceptable? With the weight of the locomotive always down, one would think that axle would ride at the top of the bronze journal and not wobble much under motion. Good assumption? Bad assumption?

Jim

[bob turner]

I would pursue the All Nation solution more carefully. Pope did not machine his own gears, and somewhere there is a big tub of those things, not only at the Pope estate, but also at whoever supplied them. They are quality gears; the problem was they were difficult to replace. All gears wear out eventually, and in the end the AN boxes were poorly assembled and the gears ate themselves way prematurely.

[webenda]

That is a big surprise to me. I would have though the steel axle would essentially never wear and all the wear would be in the bronze. Look how wrong you can be! Interestingly, the gear is still good (go figure that).

Jim

Dust is a possible causative agent. Dust embeds in softer bearing materials where it goes to work on rotating or sliding parts.

Maybe oil or grease in the axle bearing blocked dust from reaching the gears.

Bearing Bronze hardness Brinnel 65
Mild Steel hardness Rockwell B71 (Brinnel 126)
Aluminum Oxide (mineral dust) 9 Mohs (Diamond is 10 Mohs, steel is 4-4.5 mohs.)

Preventive Maintenance: Just looking to see if bearings and gears have grease is not good enough. No matter how good the lubricant looks, it needs to be cleaned out and replaced with fresh.