Dirtbag Articulated

[bob turner]

Maroon sent an "0-6-0" in his last care package. It was the rear engine of a prewar Lobaugh Challenger, complete with the geared axle coming out of the top. Someone had also cut it up to fit a USH-style gearbox (I hate it when folks get loose with a Dremel tool).

Fortunately, I have the skill to fix such things, and just jumped on it, making it bottom-open and restored to the 1/4" width that Lobaugh is famous for.
So then what? A half a Challenger?

About three decades ago NWSL came out with a "Hi-Lo" gearbox arrangement - an idler setup for the rear engine and a non-idler for the front, giving the slope required for a driveshaft from a giant can motor. It was flawed in two ways - one, you could see the drive shaft, and two - the forward axle gear was brass, which does not survive well as a worm gear (bronze is okay, and Celcon acetyl, which was Raoul's usual worm gear material, is very long lived).

Raoul sent me the pilot kit - for my evaluation. I had a Challenger under construction at the time, so installed the kit in that, and made a haphazard boiler out of a piece of steel exhaust pipe and a leftover SP style cab. I wasn't going to cut a genuine Lobaugh boiler to accommodate the high rear drive shaft, so hence the makeshift boiler.

So I pulled the boiler out of storage, attached Maroon's 0-6-0 to it, and then started to think about a front engine. I found a set of Baldwin Disc Lobaugh drivers in my pile, so half of them went into the forward frame, coming together with two strips of 1/4 x 3/4 brass, and a pair of lightweight CLW PS-4 cylinders. The pilot beam is aluminum, and the cow catcher is an escapee from a PSC project.

I have not been powering locomotives for a while - I know how to do it, but do not really get off watching trains go round and round. And before you suggest it I think I would rather do almost anything other than complicated switching moves. But this one gets power - now set up for a Mod O.6 on the rear engine, and a Mod O.5 on the front.

Here is a preliminary photo:

[R.K. Maroon]

Bob, I am trying to understand the Hi-Lo arrangement. My understanding is that the input shaft on the idler gearbox on the rear engine sits higher above the rail than the input shaft on the non-idler on the front. Further, I am guessing that the input shaft for the rear gearbox would pass through this gearbox and be aligned in such a way as to pass through the front gearbox, with a universal joint at the pivot point of the front engine. The driveshaft would have to run at a downward angle from back to front to accommodate the different height of the idler and non-idler gearboxes. That would mean that the motor would have to be mounted at that same downward angle. If not, there would be a universal joint between the motor and the rear gearbox. Is the only reason for the use of the tall gearbox on the rear engine the large diameter of the motor? Or is there some other reason why one gearbox is idler and the other one not?

Jim

[webenda]

Interesting.

[up148]

I will let Bob expand, as I bought a set (might still have them), but never installed the NWSL articulated gearboxes, but that's how NWSL lists them for sale. My understanding is, the front gearbox is shorter in height so it is hidden between the drivers, whereas the back gearbox is taller.

[bob turner]

That was the plan - a driveshaft that was concentric and a straight line through the motor shaft all the way to the front engine gearbox. I think NWSL included a horney ball U joint, but the better way is a speedometer cable with a square slip joint.

The problem (mechanical) was that the rotation of the rear idler gearbox was one way and the non-idler front was the other - Raoul had designed both to use Celcon axle gears (called worm gears, as opposed to worms) so to get both rotating the same way he just used the reverse worm in the tower gearbox and its associated brass idler gear in the front. The brass gear made it around my test loop maybe 20 times before failure.

The visual downside was the rear gearbox showed, and so did the shaft going from the rear to the front. I may have a photo, which I would have to scan and load before showing it here. In the meantime, I should have digitized photos of a much better arrangement. Let me check.

[bob turner]

Yes. This is my preferred method of powering an articulated steam model:



The mechanism is under my OSN "Back-up Malley." It runs like a watch, and is one of the few locomotives that sort of stays on my outer test loop. The front gearbox is a Mod O.6, and the rear - you cannot see it - is the smaller Mod O.5. The gear ratios are different, so it goes in and out of synchronization every 24 driver revolutions. You cannot tell it is periodic - you can tell that it does not go around the track always in the same synchronization, like most model articulateds.

But the big deal is you cannot see the driveshaft. To me this is really important in a steam model, along with the idea that I can have round boiler bellies without giant slots.

These are 65" scale drivers, but I have done the same thing using two smaller O.5 gearboxes on my Log Mallet, which uses 54" drivers. This thing is really powered, and does run with a small Escap motor. It has ball bearings on all driver axles, something I will never do again (alignment is critical, for one thing).



It is freelance, but approximates locomotives used by Long-Bell, Weyerhaeuser, and others in the Pacific Northwest. I might someday convert it to tender drive so I can use an 8000-series Pittman, but for now it just rests on the display shelf.

[bob turner]

Rather than look through my hard copy photos, I found this - might be HO, but you get the idea. Have to endure an ad at the beginning:

https://www.youtube.com/watch?v=wjhf__aoDuY

[bob turner]

Half a year ago? How time flies!

I converted the rear frame to Baldwin Discs, and freed up both mechanisms so they roll without weight on them. Now it is time for the driveshaft.
It has been well over two decades since I did the above MM2 for OSN - older readers might remember a ten part construction series. So I had forgotten the constraints. One was the driver boxes have to be skinny to accommodate the wider NWSL box. Another was that, since the drive shaft is so low, the rear frame has to be dished out to accommodate even a speedometer type flex drive.

I found a new way to make the sliding joint work - I filed the front gearbox shaft square, and soldered a 1/8" square piece of brass on it - then I polished the brass for a slip fit into the next largest square tube (K&S still produces these). The slip joint on this model is out in the open, so when I join the two engines, it is not a "feel in the dark" problem. Also, I no longer have to square up the end of the speedometer cable - just tin it and solder the tube on. Lots easier and quicker.

Track test next week, after I get that Lobaugh Challenger off the #3 loop. Maybe a photo if I get the mechanisms all prettied up -

A note on balance - forward engines for Challengers are notoriously nose heavy. I make my forward engine cylinders as light as I can - the big Mallet got an aluminum cylinder block. This one uses the PS-4 castings, which means the cylinders are almost hollow shells. On the Challenger, I added a huge brass one piece pedestal binder to the rear drivers, and a 1/4" thick steel weight under that that goes forward partway around the gearbox. That, and the lead truck has a potent spring . . .

[up148]

This is an interesting thread and I'm glad it was resurrected and I don't want to highjack it, but....... Since I'm messing with the PSC Challenger and will be for some time to come, this information and any driveline information is good. Since this model has a the stock KTM driveline, I doubt I'll need to do anything to add longevity, but I would love to hear anything that might improve performance. I've never reworked a KTM driveline so all comments are appreciated

I've communicated with Sarah Griessenboeck about her removeable cab (yes I'm doing it) and she included photos and information about the repowered driveline she's made/making for her USH Challenger. Pretty much everything is new including the drivers & tires, bearing in the stock blocks and more. But, it was very complicated and to paraphrase her comment, she's not sure it's worth the effort and she's thinking of going a different direction. This is good news for me, as I don't possess the machinery or skills to do what she has done. But, she was very gracious with her information, especially to a know nothing like me.

Butch

[bob turner]

I was getting ready to post a photo of a similar mechanism, but realized I had already done so a couple posts ago. While I hate repeated photos, here it is again, with more comments.



The big points: The motor is angled down quite a bit to match the mostly horizontal drive shaft. That is Toyota vacuum line making the bend. My new mechanism uses the same idea, but a short hunk of speedometer cable is in there to avoid the rear driver bearing, which in this case extends completely across the axle, and is covered by a piece of sheet metal to strengthen an area the previous owner had modified with an errant Dremel grinder.

I will get photos of my connection to the front engine in a couple days - suffice to say that I have become tired of the connection being under the rear cylinder block, where I cannot see it when sliding it in place. Oh - and to dazzle you with the nice end mill slot under said cylinder block to clear the speedometer cable. As always, note that the gearbox shafts are all behind the drivers, so you get the illusion of a real steam locomotive - one without shafts and gearboxes showing in the side view!

Finally, note those gorgeous dummy driver springs. Bob Stevenson has the master, and it is cored for an easy #52 drill bit, so you can hold them to the frame with an 0-80 screw. Alas, my source of steel hex head 0-80s has become either unaffordable or extinct. I have to use cap screws or studs with nuts now.

[ScaleCraft]

I used a lot of NWSL over the years. Was a dealer for a long time.
If I recall, the SET for an artic had a reverse pitch in lead box.
If you come up with a loose rear box, and a non-matched lead, yes, doesn't work.

[bob turner]

Yeah, me too. Raoul gave me a 40% discount. Wish I had stocked up on the 653-6.

The Hi-Lo was not a roaring success. First, it showed behind the drive wheels, a cardinal sin around here. And second, it used a RWG, or reverse worm gear, made of brass. That gear would make about four laps on a semi-large loop before turning into brass shavings.

Mort Mann ran into the same problems. Turns out that brass is a horrible gear material. For a while there I was changing out axle gears on Sunset locomotives (Third Rail and later Sunset corrected the problem by using good bronze gear material, and NWSL produced Celcon gears that also were very long-lasting).

But good news! Today my Dirtbag Articulated had its first test run. Only one short - a dummy driver spring had rotated into an insulated driver tire, giving an intermittent short. Fixed it and made one complete loop around the test track. Small Buehler motor. May change to an 8434 Pittman down the line.

Time to bolt the boiler on to Gersh's Challenger, and then bolt the boiler on this rather smaller articulated. Yippee!

[bob turner]

Boiler on, test laps complete.

Gersh wants a paint job on the Challenger, with decals. Guess I will have to clean out the airbrush and look for appropriate markings. I am definitely not the world's best painter.

I will get photos of both - soon.

[bob turner]

"Soon"= a month and a half.
This thing has survived about thirty trips around the test track dragging three Lobaugh "Mobilgas" tanks and a caboose, without any major hiccups. It is about to get retired - I may put some pipes on, just so I can paint the fittings red. Oh, and cab window mullions for exactly the same reason.

It is "dirtbag" because it is made of an old exhaust pipe and a cab I had laying around many years ago - used strictly for testing articulated engine mechanisms, and never intended as an actual model. I put it in the 900 class, partly because very early SP Mallets had that series, but mostly because it was so easy to snip out of the decal sheet. If it ever becomes an actual model with injectors and check valves it will become MM-3 # 3932.



I can see I forgot to tighten the rear mounting screw - looks like it is sniffing for peanuts. Easy fix.

[bob turner]

Well, these things have been going around and around almost weekly since June of last year. I did crack a plastic worm on a Pacific, and this one had its drive shaft separate between engines, but both were very quick fixes. Maroon was by, and did some very steady handed iPad movies. We will try to get at least a link in here.

I don't think Jim was impressed with my "exhaust pipe" 2-6-6-2 above, but I am - I will try to get a video of that, and the Sharks, going around and around (and around). No derailments while Jim watched, and nothing so much as faltered. And my track has to be the worst in the nation.

Of note - Jim expressed interest in my Mongrel Mogul, so I set out to power it. Turns out Lobaugh had a very special open frame motor for these things that just barely fits in the cab - so I pulled down my lost wax 0-6-0 and opened it up, lubricated it, and applied power for the first time in 30 years. Runs great! The Mongrel Mogul also ran, with a temporary "tender drive" (my hand was the tender, holding the motor. I will fix that this weekend).

So - maybe I will get some operating links soon, and definitely some photos in maybe a week?