Machine Shop / Locomotive Drive Work

[bob turner]

I found that pressing wheels must be done with a jig, or they will wobble. That does not seem to be true with cast iron drivers and shouldered axles, but I could not press freight car wheels properly until I machined cups and did it on the lathe, using tailstock pressure.

[rrjjf]

Bob,

I have never had any problem centering O scale car wheels in my Cushman 3 jaw chuck and then pressing an axle into them using the tailstock. On larger axles, I center drill the axle ends and push the axle with a home made dead center held in the tailstock Jacobs chuck. When I put a wheel in the chuck with the flange up against the chuck jaws, I turn the lathe on briefly and look down at the wheel as it rotates. If there is any visible wobble I re-chuck the wheel. This is seldom necessary. I cannot tell you how many wheels I have installed in this manner.

Joe

[R.K. Maroon]

A friend of mine has a CLW GP35 in GM&O markings. As mentioned in the "Paint Shop" thread, the GM&O GP35s came with AAR type B trucks from a trade-in (I would guess from an Alco FA). Appropriately, the builder of the modeler replaced the stock Blombergs trucks with CLW sprung AAR type B. They interfered with the chassis at one end (by a large amount), so he moved the kingpin in. This shortened up the drive shaft to the tank mounted motor and caused problems on curves. He tried remounting the motor but was still not happy with how it ran. I volunteered to replace the tank drive with a tower drive. Here is the modified chassis frame:



There are three modifications here. First, I lengthened the rear bolster (on the left) by soldering a piece of brass bar stock to the original cast bolster and then machining it for properly lengthened phenolic insulators. Here is a closeup:



The second modification was to add the two bars in the middle across the chassis rails, as shown in the first photo. These support the tower and the motor. I thought that was all I would have to do here but it turned out the air tanks and piping interfered with the rear truck. So the third thing I did was to shorten the tanks and refit the piping.

Photos of the tower and motor setup next.
Jim

edited for photo link

[bob turner]

I may have spare parts like that. Remind me.

[R.K. Maroon]

Here is a shot of the first "fit check" assembly of the tower drive that I put together for the GM&O GP35 with the AAR type-B trucks:



Again, this is a CLW model originally equipped with a tank drive and Blomberg trucks. With the the AAR type-B trucks installed the drive shafts to the tank-mounted motor were too short to be practical -- thus the switch to tower drive. The tower and motor mount is made of several small pieces of brass flat and aluminum angle, all screwed together. All threaded connections are tapped -- no nuts to install, come loose or lose. If I was making a bunch of these I might have bought solid material and hogged the brackets out, but this was fast, cheap, and functional. Before it was over I wound up having to narrow the aluminum angle to fit through the locomotive deck. I also found that it was a fool's errand trying to hold alignment between the motor shaft and the tower input shaft. I am now using Bob's famous Toyota hose instead of the u-joint shown.

Jim

[LarryK]

image

[R.K. Maroon]

I assume from Larry's post that he was having problems seeing the image. He must have a Mac, but either way it reminded me that one must modify the default link that Dropbox gives you for Mac's to see the posted image. I have modified the photo in the recent post as well as the two before that. Please let me know if anybody is still having problems seeing the images.

Here is a closeup of the motor/tower assembly:



The two pieces of brass bar stock at the bottom of the stack on each side of the tower were soldered into the frame once I was happy with the fit. These two pieces are actually four pieces. I don't have a good supply of .125" bar stock so I soldered two stacked pieces of .063" stock using the megawatt resistance unit to get what I needed.

You can tell the motor is not new. It was pulled from an locomotive assembly and had a pin soldered across the shaft as part of a home-made ball-and-socket connection.

Jim

[bob turner]

Did you make the tower? Any noise or vibration on the lower drive shaft can be eliminated with Toyota hose at the tower; quality U joint at the truck.

[R.K. Maroon]

Did you make the tower?

No, the tower is a new-old-stock KTM. I found several of these at an estate sale a couple of years ago. I don't own much imported brass and thus don't have any experience with this style of tower. However, they have better bearings than the old crappy OMI towers so I was willing to give them a try.

Any noise or vibration on the lower drive shaft can be eliminated with Toyota hose at the tower; quality U joint at the truck.

There is just such a setup on an SD45 shown in the first page of this thread.

Here is a closeup of the setup I used to solder the brackets to the chassis that were needed to mount the tower and motor:


The trick was to get the brackets soldered with out desoldering the air tanks. I have found the resistance unit is well suited to this kind of work, as it provides very localized heat. It's fast and easy as long as you have a good spot for the ground lug. Sometimes you don't, and for those situations I have found that two probes can often be used to good effect if you can get the work firmly secured while you double-probe it.

Later I discovered that the tanks had to be shortened, so I wound up removing, modifying, and attaching them. The situation was then reversed: desolder and resolder the air tanks without desoldering the tower-motor brackets. Again, I had no problem with this operation.

Jim

[R.K. Maroon]

I still need to get the GP-35 chassis described above into the paint shop, but in the meantime I thought I would share a photo of some never-seen-before-by-me damage to an All Nation gear tower.


This gear tower was removed from an NW-2 that passed through my hands recently. The unit is one of the older models, as indicated by the straight gears and the square receiver for a speedometer-cable drive shaft between the motor and the upper gear shaft of the tower. This receiver is the short end of the gear shaft and can be identified by the large blob of solder on the end of it.

EIther the shaft was too long to begin with, or perhaps the solder blob on the receiver somehow jammed it up, but either way there was a large amount of thrust between the motor and the tower. Over time this caused the steel gear hub on the upper gear shaft to eat its was into the trunnion on the tower, as can be clearly seen. A new trunnion is shown for comparison. Even with the amount of wear shown there was still a good amount of thrust in the shaft.

The wear on the trunnion was sufficient to cause a half-width misalignment between the gears, and as such they are now asymmetrically worn. They have some number of hours of life in them but everything else here is so worn that (for me) refurbishment of this drive is not really worth the effort. At any rate, it's a good lesson -- I have in the past set up the plastic-tube drive shafts that displaced the speed cables a bit snug. I will henceforth make sure there is a skosh of end-to-end clearance just to be sure there is no residual thrust.

Jim

[J. S. Bach]

...snip... as indicated by the straight gears ...snip... Jim

My favorite AN drive, I do not really like the chain drive.

[ScaleCraft]

My favourite, also....don't need a sound system, and certainly settles loose ballast in.
Helical cut, and chain, no.

[bob turner]

Looks a bit like the gear itself slipped on its spline. Don't throw it away. Yes, there must be some slack in there - the speedometer cable shouldn't bottom out. I really like one NWSL horney ball at the transmission, and Toyota tube at the motor.

[R.K. Maroon]

I mentioned in the post on the recent Southwest O-scale Meet in OKC that I was on the hook to provide an Alco PA for my brother Pete's Sunbeam. The prototype stayed in Daylight colors even though the cars had the later silver with red stripe scheme. Pete and I are also interested in building up a trainset for the Cotton Belt's Lone Star. That train likewise had a PA in Daylight colors. As such, our plan is to build up and finish two PAs at once. I have the following assortment of CLW first-generation cast PAs (or to be more accurate, five PAs and one PB):



None of these are ready to run, and, as expected, they are in a wide range of condition. One thing they have in common, however, is the presence of the dynamic brake unit on the roof. Unlike the later CLW PAs, which had the dynamic brakes as a separate detail piece that could be easily left off, the first generation units had the dynamic brakes cast into the main shell. So the first steps in the project will be to survey these for condition, select the two units that are best suited for the project, and remove the dynamic brakes units. More to come.

Jim

[bob turner]

You have almost as many of those as I do! Bob said he made 600 total casting sets, so we are "one percenters." More photos, please?