Replacement Athearn Bombardier BiLevel Trucks, aka making the train roll

[mmagliaro]

There are the bronze Bergeon bushings, right?   Durability and pickup will be much better from those than with brass.

So, if I understand this correctly, the bushings will be mounted in the frame such that they cannot slide inward and touch the plastic axle tube?  And the slight lateral play in the wheelset will be accomplished by letting the axle slide back in forth in the bushings, so the wheel backs can touch the outside faces of the bushings only (not the frame) and the bushings cannot move inward to touch the axle tube?  If so, I completely agree that is the way to go.  (And it's exactly how I designed my 0-6-0 engine project, by the way). 
As long is there is just a hair of "play" or "float" of those bushings in the frame, they will happily fine a place to align themselves on that axle and it should roll smooth. 

If you want to, you can lay one of those bushings flat on a piece of 400 grit sandpaper and swirl  it around with your finger to sand it thinner.  Peteski is correct in that the thinner you make that bearing, the less friction you will have.

A bushing bore of 1.25mm with an axle of 1.2mm  leaves .002" of slop.  That is a little high for a bearing, believe it or not, so they might be a little too sloppy in there.  But time will tell. 

This is a great project for so many reasons.  Watching with great interest!

[atsf_arizona]

Watching with interest as well!!!

[CNR5529]

Any thought for allowing electrical pickup?  I am in the starting phase of putting LED lights in a cab-car of these units  (headlight & flashing ditch,  red rear class lights). I have the Streamlined Backshop Wheel Wiper kit for use with the standard trucks, but if these trucks pan out, would love to improve the overall performance.

That was one of the reasons for leaving the bottom of the bushings exposed. I wont go too deep into the electrical design yet, as this is where @craigolio1, AKA the lighting package whisperer, really um... shines... But yeah, we figure pickup should be fairly simple to do should it be needed.

There are the bronze Bergeon bushings, right?   Durability and pickup will be much better from those than with brass.

Yes, the bushings chosen are bronze, sorry about the confusion.

So, if I understand this correctly, the bushings will be mounted in the frame such that they cannot slide inward and touch the plastic axle tube?  And the slight lateral play in the wheelset will be accomplished by letting the axle slide back in forth in the bushings, so the wheel backs can touch the outside faces of the bushings only (not the frame) and the bushings cannot move inward to touch the axle tube?  If so, I completely agree that is the way to go.  (And it's exactly how I designed my 0-6-0 engine project, by the way). 
As long is there is just a hair of "play" or "float" of those bushings in the frame, they will happily fine a place to align themselves on that axle and it should roll smooth. 

Exactly.

If you want to, you can lay one of those bushings flat on a piece of 400 grit sandpaper and swirl  it around with your finger to sand it thinner.  Peteski is correct in that the thinner you make that bearing, the less friction you will have.

I suppose there is nothing stopping us from doing this anyways in the future. I just made the truck frame that wide to prevent it from cracking, but the bushing itself could be thinner. You would just need to ensure that the bushings are seated slightly proud of the truck frame.

This is a great project for so many reasons.  Watching with great interest!

Thanks! I am excited to see results (good or bad) when the new trucks come in!

[craigolio1]

My idea for electrical pick up was to solder a magnet wire to the outside of each bushing, coming off perpendicularly.  Once snapped in the frame the wire would be open to the exposed part at the bottom and won't affect fit or come any where near any moving parts. I'm going to mount my cab car wheelsets with Micro Trains king pins. The centre can be drilled out, all four magnet wires fed up through the centre, and the truck will swivel with out any issue. I'm in the process of installing a decoder in my cab car with the hope that I can reveal the completed working product shortly after the truck testing.

Apparently NEO Lube conducts and it was suggested that perhaps a bit of that in each bushing would improve the efficiency and promote conductivity.

And about the 1.25mm bushing on the 1.2mm axle. That was the closest size I could find and when I slipped it on it didn't feel to me that there was any play. Obviously my fingers are crude instruments for measuring those kinds of tolerances but I'm still optimistic. We're not dealing with a shaft spinning at 12,000 RPM hear. That said my experience with this stuff is very minimal.

I hope it works!

Craig

[RBrodzinsky]

My idea for electrical pick up was to solder a magnet wire to the outside of each bushing, coming off perpendicularly.  Once snapped in the frame the wire would be open to the exposed part at the bottom and won't affect fit or come any where near any moving parts. I'm going to mount my cab car wheelsets with Micro Trains king pins. The centre can be drilled out, all four magnet wires fed up through the centre, and the truck will swivel with out any issue.

Apparently NEO Lube conducts and it was suggested that perhaps a bit of that in each bushing would improve the efficiency and promote conductivity.

Can magnet wire handle enough current for a decoder? I have always thought it was limited to max of between 20-30ma. Would your idea still be viable with decoder wire (36 awg)?

[craigolio1]

My wire is 34awg. Totally different. Haha.

With four wheel pick up those 4 combined 34awg wires effectively create the equivalent of a 26awg conductor, which I think is plenty. I doubt the wires on my decoder are any bigger.

Also this may be carnival math, but current out can't really be too much more than current out and I'm going To be running 5 little LEDs with larger than normal resistors (I don't like my trains to have blinding lights.).

Maybe someone who knows for sure can chime in.

Edit: alternatively, instead of soldering, I could probably just pinch the wire between the bushing and the top of the seat when I install the bushing. The wires are so fine I doubt it would change the fit much, and every one would be the same.

Craig

[jagged ben]

I'm so glad to see that upon revisiting the thread, electrical pickup has been addressed.   

Can magnet wire handle enough current for a decoder? I have always thought it was limited to max of between 20-30ma. Would your idea still be viable with decoder wire (36 awg)?

With four wires to each rail that could handle roughly 3-4 times as many amps (allowing for intermittent contact at times).   If you're just doing lights I can't imagine it would cause a problem.  If you're doing sound as well...   How many wants does a sound decoder draw if it's just horn and bell?  Note that if you don't have a continuous use (i.e. no prime mover sound playing constantly) then the thermal load on the wire will be less. 

[nkalanaga]

CNR5529:  Looks good to me.

Peteski:  I have long suspected that part of the reason Minitrix used their bushings was for better pickup.  The zinc alloy(?) frame wasn't polished, and would have had about the same pickup quality as the early Atlas/Kato RS3s, which is to say, not the greatest.  The bushings would have been much smoother, so make better contact with the axles, and stationary in the frame, so would at least have consistent contact there.

As for magnet wire, what are our motors wound with?  It has to be able to handle the full motor current whenever the motor is running, and I can't imagine a passenger car decoder drawing more current than a working motor.

[daniel_leavitt2000]

Three words: Micro Roller Bearing.

The type used for the counterweight in automatic watches or something similar.

[craigolio1]

In the Kato Amfleet thread someone was experimenting with tiny roller bearings. I think the same size or slightly larger than the bushings we chose here.

There were a couple of things that turned me off.

First they are wayyyy more expensive. I need 54 of them and I couldn't afford them.

Then, roller bearings don't from what I understand pick up electricity well especially if you lube them, so then you have to use wipers which adds more friction.

And finally, I was able to find bearings with 1mm bores but not 1.2mm. Doesn't mean they aren't out there. I just couldn't find them.

I'm sure there better, I'm just optimistic that the bushings will be good enough.

If someone can find a 3mm bearing with a 1.2mm bore then use it instead.

Craig

[peteski]

1. Magnet wire comes in many thicknesses and is available as heavy as 12 AWG or heavier if that is what you need.    So, you could get for example 28 or 26 AWG magnet wire.  But I agree, for a function-only decoder driving few LEDs the total current will be fairly low.

2. Why is (insulated) magnet wire needed?  The truck is made from a non-conductive material and the car is made from plastic. You can use bare conductors to pick up current from the bearings.   Then bundle each side together at the top of the truck and solder to a flexible insulated stranded wire to route it inside the model.  If you need thin bare wire just strip some stranded wire and then use the strands.

[nkalanaga]

Since the bearing isn't turning you wouldn't have to solder the wire to it.  Use a piece of spring wire, such as phosphor bronze, and bend it so that each end presses against a bearing.  Then solder the lead into the car to that, and you won't have to try to solder to the bearing without damaging the truck, or the bearing.

[craigolio1]

Peteski,

I'm planning to use drilled out Micro Trains king pins to router the wires up into the car. Are you saying to use bare conductors, and then transition to an insulated conductor before all four come together in the kingpin?

Nkalanga, that's a good idea as well.

Does anyone know what, if any, risk there is to soldering directly to the bushing? Deformation perhaps?

Craig

[CNR5529]

Test trucks were ordered on Friday, and I just got notice that they are shipping out today. That is probably the quickest turnaround I have experienced yet. Awesome!

[peteski]

Peteski,

I'm planning to use drilled out Micro Trains king pins to router the wires up into the car. Are you saying to use bare conductors, and then transition to an insulated conductor before all four come together in the kingpin?

Nkalanga, that's a good idea as well.

Does anyone know what, if any, risk there is to soldering directly to the bushing? Deformation perhaps?

Craig

Exactly.  Bare wires within the truck assembly and then thin flexible insulated stranded wore up into the kingpin. Something like TCS decoder wire (I fund it more flexible and easier to solder than Digitrax wire). Or ESU also sells excellent decoder wire.

I would not worry about deforming the bushings by soldering anything to them.   And I do like solid soldered connections. Do you know if those bushings are brass, bronze, or sintered brass or bronze?