Maybe a fix for the "wires soldered to truck contacts" problem

[OldEastRR]

While a friend and I dealt with broken connections to wheel pick-ups of an old old BLI Precision Craft Models E7 yet again, I wondered if there was a way to completely end or make very seldom the wonderful property of wires soldered to truck pick ups detaching themselves. I half-seriously proposed putting a gob of silcone sealant over the wire and contact, when my friend said "Why not use shrink tubing?"
So we went ahead and did that. You have to use a very short piece of shrink tube but it makes a very good support/reinforcement over that weak point where bare wires leaves the insulation to solder to the pick=up.

Now to see how long it holds up (this loco has terrible pick-up), but Maybe some of you may try it to fix your wire/contacts breaks. I'm thinking that this fix is pretty much permanent, and as the other wire connection on these trucks break as expected I'll apply it to them.

Really don't know why the big design brains at the major train mfgrs didn't ever think of a tough but flexible all-encompassing reinforcement for this problem (which has been around since the beginning of N scale -- hell, it may have existed in prehistoric (HO) times)
Ah, yes ... it costs too much to do. 

(this would have been a great solution for my N Atlas S-2 flaw)

[u18b]

I think it is a good idea but will only delay.

The real issue is flexing- wires that flex will always eventually break.  By using heat shrink tubing, you are simply moving the flex point.  Eventually it will break at the new point.

You are correct that the solder point is a weak point.  So I like your solution.  Let us know how it does.

[McKeen]

If it’s the conductor failing from fatigue, then then the application would call for a wire specifically designed for repetitive flexing, which is what a swiveling truck does
Wire from the Home Depot, decoder wire, wire from a mouse cable, or ear buds, or whatever readily available wire you’re using, will usually fail at somewhere near 40-50k flex cycles.
You can source wire that will have a much longer service life than what the hobby shop or big box carries.
Look for “Robotic” or “Ultra-flexible” wire, its service life is several (2-3) million flex cycles.
It’s used in automated robotic systems of automotive/medical /high tech manufacture. Also has many military and space applications.
Should be a once and done in a model railroad truck.

[wm3798]

The problem isn't the flexing of the wire itself, it's the point where the wire becomes solid at the solder joint.  I've found that by simply crossing the wires before they turn to go up through the chassis is enough to move the flex point away from the solder joint, and instead at the twist.  By making the solder joint more stable, the problem is reduced considerably.
Lee

[Cajonpassfan]

This.
Otto K.

[wm3798]

I've also experimented with the shrink tube "boot", and it creates an oversize situation that affects the truck's ability to pivot freely.  You'd have to nibble away either the clip on the truck, or the opening on the frame... and that's just asking for trouble, IMHO.

Lee

[OldEastRR]

The problem isn't the flexing of the wire itself, it's the point where the wire becomes solid at the solder joint.  I've found that by simply crossing the wires before they turn to go up through the chassis is enough to move the flex point away from the solder joint, and instead at the twist.  By making the solder joint more stable, the problem is reduced considerably.
Lee

Not sure exactly how to accomplish this as I can't recall any modern N loco having enough space between the truck and frame for wires to cross over. (Sure in HO no prob!!). In the case of this PCM E7, the wires go straight up into dedicated slots in a plastic insert right above the trucks. So wouldn't be able to cross them except at least 3/16" above the joint. I think the Atlas S-2 would also be hard to do this with.

I've also experimented with the shrink tube "boot", and it creates an oversize situation that affects the truck's ability to pivot freely.  You'd have to nibble away either the clip on the truck, or the opening on the frame...

I think every engine presents a different problem. Yes, you have to make the shrink-wrap section as short as possible, but in the case of this loco the plastic guide/insert over the wires was slightly trimmed to provide just enough clearance for the end of the shrinkwrap to clear as the truck pivots. What the end result is the wire basically becomes part of the pick-up fixed in the truck, so it doesn't flex until it gets through and above the base of the loco frame. So when the truck turns, the wire turns with it (no flexing) and the flex happens in the large loose loop of wire going along the frame to the decoder. Instead of a flex point, it's a flex arc with little stress.

My friend and I debated whether to dissemble all the trucks and do this to all the contacts, decided it could wait until needed. Then this reliable ol' PCM loco decided to throw a rear traction tire so it's to the backshop for a complete remake.

[tehachapifan]

If only the manufacturers could come up with maybe a contact strip system and eliminate truck wires altogether. Oh, wait!

Seriously, could there be any better design than the contact strip system regularly used by manufacturers for a couple decades before now?

I can't think of one problem I had with a loco because of contact strips, save for the need for very occasional cleaning.

It was a magnificent design! I am puzzled that manufacturers are moving away from it.

[wazzou]

If only the manufacturers could come up with maybe a contact strip system and eliminate truck wires altogether. Oh, wait!
It was a magnificent design! I am puzzled that manufacturers are moving away from it.

Sound, supposedly.

[craigolio1]

If it’s the conductor failing from fatigue, then then the application would call for a wire specifically designed for repetitive flexing, which is what a swiveling truck does
Wire from the Home Depot, decoder wire, wire from a mouse cable, or ear buds, or whatever readily available wire you’re using, will usually fail at somewhere near 40-50k flex cycles.
You can source wire that will have a much longer service life than what the hobby shop or big box carries.
Look for “Robotic” or “Ultra-flexible” wire, its service life is several (2-3) million flex cycles.
It’s used in automated robotic systems of automotive/medical /high tech manufacture. Also has many military and space applications.
Should be a once and done in a model railroad truck.

Is this what you are talking about? It’s 30 AWG.

https://www.amazon.ca/Fermerry-Stranded-Silicone-Flexible-Electric/dp/B089D16BX1/ref=mp_s_a_1_1_sspa?crid=J593ZOFKHPNQ&keywords=ultra%2Bflexible%2Bwire%2B28%2Bawg&qid=1697203061&sprefix=ultra%2Bflexible%2Bwire%2B28%2Bawg%2Caps%2C102&sr=8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9waG9uZV9zZWFyY2hfYXRm&psc=1&th=1


Here’s one just in black. Also 30 AWG

https://www.amazon.ca/BNTECHGO-Silicone-Flexible-Stranded-Impedance/dp/B01N010XA1/ref=mp_s_a_1_4?crid=865J3FMOD6GP&keywords=ultra+flexible+wire+30+awg+black&qid=1697203182&sprefix=ultra+flexible+wire+30+awg+black%2Caps%2C123&sr=8-4

34awg is the smallest I could find. The wire that ESU sells is 36 AWG. I was looking for a comparable to that.

https://www.amazon.ca/Ultra-Fine-Electronic-Temperature-Resistance-Freeze-80%C2%B0Extra-Fine/dp/B0962T57FZ/ref=mp_s_a_1_4?crid=27U4CBMD65KDG&keywords=ultra%2Bflexible%2Bwire%2B34%2Bawg&qid=1697203371&sprefix=ultra%2Bflexible%2Bwire%2B34%2Bawg%2Caps%2C84&sr=8-4&th=1&psc=1

Craig

[peteski]

The wire that ESU sells is 36 AWG. I was looking for a comparable to that.

Unfortunately, you can't always trust hobby manufacturer's specs.  ESU decoder wire labeling shows it a .5mm and 36AWG.  Both specs are way off.

European wire specs do not use AWG sizes  but cross-section in mm².  Just using plain "mm" is wrong to begin with.  From what I can determine, ESU likely meant 0.05mm² which is equivalent to 30AWG.

See https://www.rapidtables.com/calc/wire/wire-gauge-chart.html

BTW, ZIMO decoder wire is even finer than ESU.

Also, the stranded wire's flexibility is not directly related to its gauge, but to the way it is made.  You can have a 30AWG wire which consists of 7 strands of thicker wire, or one which is made of 30 strands of much thinner wire.    The 30 strand wire will be much more flexible and less prone to fatigue breakage.

ZIMO decoder wire more thinner strands than ESU wire.

Also the most flexible and fatigue resistant wire  is the one used in telephone headset cords.  It probably has a name but I don't know what it is.  It is a very unusual stranded type of wire where each strand is actually a plastic thread spirally wrapped with a thin flat phosphor bronze strip.  Then multiple of those strands are twisted together.  This type of wire is designed for maximum flex durability, but due to its design, I have never seen it available in thinner gauges. 

Having said all that, I still much prefer the "wireless" pickup designs (like what Kato does).

[McKeen]

Before I retired, the company I worked for sourced ultraflexable wire from a company named Calmont Wire and Cable out of Santa Ana, CA. It was 36AWG.
I would imagine it, or something comparable, could be sourced from the likes of McMaster-Carr, DigiKey, Mouser, or a similar industrial supplier.

i would skip Amazon.