Replacement Athearn Bombardier BiLevel Trucks, aka making the train roll

[nkalanaga]

Looking at your first chart, I'm surprised by the difference between the MT hopper and reefer.  I would have thought they'd be very close to the same.

[RBrodzinsky]

When I ran those, I too was very surprised.  All my cars (the ones in green) have FVM metal wheel sets. Notice the reefer's performance is very similar to the cattle car, even though  its mass is similar to the hopper. Made me wonder about differences in the trucks (but I didn't take it any further than wonder).

[craigolio1]

Amazing!

Time to order some trucks and fit tiny Helium balloons in my cars.

Craig

[jagged ben]

I hadn't caught up to the latest on this until now.  Very interesting.

On electrical pickup... 4 wires from each truck?  Do the three different wires of each bearing make good enough contact with each other that all provide reliable pickup?

[craigolio1]

I haven't seen the trucks yet but when I did the ones with the bronze bushings I soldered one magnet wire to each of the four bushings on the truck, and then ran them up through the middle of a hollow king pin.

I would attempt to do the same here, somehow soldering the wire to the horizontal wires as that would be the one which was in contact most often.  I haven't assessed how I'll do that yet.  If it proves to look too ugly or just not work, I'll use the bushing equipped truck as before and equip the rest of the train with the new design. 

Craig

[nkalanaga]

Rick:  Does the hopper have 100-ton trucks with 36 inch wheels?  If it does, maybe the 33 and 36 inch wheel axles are slightly different, or it could be as simple as one or more of the sideframes have been spread, or pinched, just a little over time.  It is interesting, though.

[Lemosteam]

Sorry for the bad advice, @CNR5529 !

[peteski]

So an update is long overdue... I had assembled the trucks and conducted testing right before Christmas, but unforeseen circumstances kept me otherwise occupied and I wasn't able to write up a summary of my findings. So without further delay, here it goes!

So what does this all mean? Well, generally speaking, Rev 1 trucks are better than stock, and Rev 2 trucks are better than Rev 1 trucks when considering distance traveled. In total, the rev 2 truck traveled almost 45% further than the stock truck. When the carbody was installed, the added weight did cause more friction to occur, and the end result is we have a vehicle with inboard bearing trucks which is now closer in performance to the Kato Amfleet Coach. Keep in mind I have yet to test the effects of lubricants on the Rev 2 truck.

This seems to confirm the suspicions I had at the beginning of this thread that (without using some esoteric design and components) Kato's inside-bearing truck design is as free-rollign as possible.

Contact between the truck frame and axle has now been reduced to 2 points of contact at each journal, so I see no way of further optimizing the truck design. At this point the only way I see to get better performance would be to make the cars lighter. I am looking forward to testing out a complete trainset in the near future!

Making the car lighter will decrease the reliability of electric pickup (for lighting). Probably an undesired consequence.

Thanks for your through and scientific presentation.

[CNR5529]

Sorry for the bad advice, @CNR5529 !

Not at all. I had planned to do basically this anyways, but discovered that the alternate version (plunging straight in) provided better results in the fud/fxd material. This is of course purely a problem due to the half exposed wire geometry; a normal blind or thru hole should be "drilled" instead.

This seems to confirm the suspicions I had at the beginning of this thread that (without using some esoteric design and components) Kato's inside-bearing truck design is as free-rollign as possible.

Making the car lighter will decrease the reliability of electric pickup (for lighting). Probably an undesired consequence.

Now someone has to come up with a design using actual ball bearings, and keep it cost effective... 

I suspect that any solid electrical design will require heavy use of "keep alive" capacitors. The rev 1 truck with bushings wasn't great pick-up wise, I'm guessing this one will flicker quite a bit as well.

Well, at least we have a better looking truck with improved performance. I am calling it a win!

[peteski]

Now someone has to come up with a design using actual ball bearings, and keep it cost effective... 

I suspect that any solid electrical design will require heavy use of "keep alive" capacitors. The rev 1 truck with bushings wasn't great pick-up wise, I'm guessing this one will flicker quite a bit as well.

Well, at least we have a better looking truck with improved performance. I am calling it a win!

I agree that for minimizing friction, ball bearings and very tight tolerances would be optimal. But ball bearings are very poor at conducting electricity. @mmagliaro tested that configuration and IIRC abandoned using ball bearings on his steam loco in favor of friction-type bearings to minimize electrical conductivity.

But yes, on couple of fronts, your design is an improvement over the original.

[Lemosteam]

You might be surprised how reliable this will be as long as you connect all three wires at each corner (two corners per side obviously).

[craigolio1]

I'm not sure I'm following what you mean by "all three coroners, two corners per side".

On the previous design I connected one wire per wheel, for a total
Four wires per truck and four points of contact on each rail.

This provided power but we still saw spilt second interruptions in power, which with the car trailing means we would get brief flashes of the head light as the decoder powered up and then switched to the marker lights again.

The TCS decoder I used has attachments for a keep alive cap which will solve this issue. So I planned to use the same plan of four wheel pick up.

The issue is that the wires that the axles will be contacting are hidden in the truck now where as the bushings were on the axle and had the bottoms exposed which made it very easy to solder a wire into the bushing prior to installation, and the wires were not visible while running.

What I'm trying to figure out here is how to attach wires and have them hidden. My plan right now is to flare the hole in the end of the truck a bit so that I can solder the magnet wire to the end and when inserted, the solder connection will be hidden in the hole. The wire is then bent around the end, passes under the axle and up the king pin tube as before. The down side here is that if the wire ever breaks off I can't see a way to get the brass wire out of the hole in the truck.

My other idea was to cut a channel across the end of the side frame so that the wire pick up can be bent in at a 90 deg angle. The groove would mean the bent wire is flush with the end once inserted. The wire is soldered to this and if it breaks of it can be soldered back on or the brass wire removed and then resoldered. Having that bent piece of wire would leave a sort of handle.

Craig

Craig.

[peteski]

I was under the impression that the bushing was held securely in between the wires (no play). If that's the case, using just s single wire for reliable pickup should suffice, no?

[CNR5529]

I believe what Lemosteam was talking about was the three bearing wires that make up a single axle box (which now replaces a bushing). Only two wires are ever in contact with the axle at each corner because of the longitudinal clearance in the design. As you go from pull to push, the one wire would no longer make contact, and the one that was free will now be in contact. Thus, each corner of each truck would in theory need 3 wires to be joined together for robust electrical pickup. Thats a total of 24 points to solder together per car!

If it was my train, I would use rev 1 trucks with bushings for the cab car, and include keep alive caps... but we can still conduct some tests if you want with the rev 2 trucks and pickup.

I was under the impression that the bushing was held securely in between the wires (no play). If that's the case, using just s single wire for reliable pickup should suffice, no?

The bushings are no longer in use on the newest truck design. The bearing wires rest directly on the axles, effectively replacing the bushings. There is 1 thou total longitudinal play between the two guide wires and the axle, to allow for some freedom of motion.

[peteski]

The bushings are no longer in use on the newest truck design. The bearing wires rest directly on the axles, effectively replacing the bushings. There is 1 thou total longitudinal play between the two guide wires and the axle, to allow for some freedom of motion.

Um, looks like I had a serious senior-moment. Never mind.