# Ball bearing wheel with power pickup, not picking up power well



## Chata86 (Dec 5, 2010)

I bought some ProWheel ball bearing wheels with power pickups for a caboose. When I first powered it on, with a stationary car it worked fine. But I noticed that when the car is moving it only conducted about 10% of the time. I measured that the wires conduct directly to the center outside hub of the wheel, but that hub doesn't always conduct to the wheel itself.

After running around the track for about an hour conductivity has increased to about 60% of the time but only at low and medium track speeds. The track is new, and I'm judging conductivity by the appearance of the lights in the caboose.

Do ball bearing wheels have a break in period? Or perhaps they were over packed with grease? Or perhaps it's intended to use conductive grease, but didn't?


Thanks!


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## Greg Elmassian (Jan 3, 2008)

These are the ones from Train-Li? 

They should be better than 10%, and I see they did get better. But you cannot assume they contact all the time, it's probably not the bearings, but dirt and the wheels bouncing. 

How many wheelsets (axles) did you use? 

I'd advise a small circuit and a "storage capacitor", to even things out. 

There is no such thing as conductive grease really (from a practical point of view you can use), and the bearings should have light oil in them. Being brand new, they should not have any contamination in them. 

When new, the races might have some oxide on them or need to wear in a bit to make better contact. 

If I want better contact, I use them on all 4 axles. 

Greg


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## Chata86 (Dec 5, 2010)

I put them on one of my little 4065 caboose. There are only two axles. I did connect both axles in parallel, so I didn't expect so much outage time. I thought about the capacitor too, but then I wondered that there was so much outage time there wouldn't be enough storage time.


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## Greg Elmassian (Jan 3, 2008)

Yes, with 60% on time might be a problem, but it's all in how big a cap you use and how much current the lights draw. 

I normally get more like 80% but I have very clean rails, and SS and DCC, so there is constant full voltage on the rails. 

If you want more "on time", would recommend going to LEDs and cap and diode and resistor setup. 

Greg


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## Chata86 (Dec 5, 2010)

I do have LEDs. It's wild how different it is from the metal wheels with brushes. Those are 100% on.


I suppose it could be bouncing causing this, but given the outage time, it'd be more like bouncing on the moon than on planet Earth. 



Maybe I should video it and you could make a remote diagnosis


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## Chata86 (Dec 5, 2010)

Conductive grease has silver in it. But maybe you're saying the wheels are not greased anyway, there is just some light oil in there?


http://www.grainger.com/Grainger/CHEMTRONICS-Silver-Conductive-Grease-1UYE2


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## Greg Elmassian (Jan 3, 2008)

Yeah, light oil...otherwise grease would be taking away from the free rolling part. 

Conductive grease is dangerous, because it normally gets all over the place, and usually shorts the wheels out (the insulators are normally pretty small). 

There are real conductive greases with copper, silver, gold, and even graphite (not as conductive). LGB sells a "Conductive" grease, but it's non conductive. 

Greg


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## Chata86 (Dec 5, 2010)

I've heard the LGB rail grease is graphite, and bad for carpet. So I stay away from it.

I lubed the bearings and axel with silicon spray. Hammered the axles on tighter. More free running and much better conductivity. I guess they just had machining grease on them or something?


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## lownote (Jan 3, 2008)

Should do better than that. I've had good luck with the Train-li wheels. But in a situation like you describe, I would also add a capacitor to the circuit. They charge almost instantly, and they virtually eliminate flicker


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## Pterosaur (May 6, 2008)

Odd, with LGB bb-wheels I get light 99% of the time (I use 2 per car). Gregs idea of a "storage capacitor" is a good one though...I may have to consider changing to this type of set-up and LED's for my lighted cars.


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## Axel Tillmann (Jan 10, 2008)

I have measured LGB ball bearing wheels and and our ball bearing wheels and neither when taken out of the shelf ever cuts out. They fluctuate between 20 Ohm and 300 Ohm with an average of about 120 Ohm for the ProWheels and about 180 Ohm or so for the LGB wheels. After spraying a touch Teflon spray into the bearing the average of the ProWheels went down to about 40 Ohm or so. When I wieght down the car the avarage approached below 10 Ohm. 

The final advise, after one receives the bearings or when the cars were stored for a long time, a quick Teflon application improves the running qualities. However, on my layout (and many others I spoke to, regardless of the brand) for finest operating results a capacitor is recommended. In particular if you use ProLights. Why? Unlike incadecent bulbs the ProLight lightstrip use an electronic to regulate the Voltage to the 6 LEDs. This voltage regulation is more sensitive to fluctuation then a direct hook up. Right after the diode bridge (marked +/- on the bridge) is the connection point for the capacitor. Take two thin wires and run them into the toilet stall and all flicker is gone.

On previous threads (Greg started this ones) there was a discusssion about engine power pickup over ballbearing wheels versus throgh brushes and pickup shoes. Greg came to the conclusion if memory serves me well that the constant rotation of ball bearing wheels at high currents was more reactive to the fluctuation. Now with LED hookups we don't have the current draw problem that Greg described, but we still have the underlying change in resistance. Reall ynot a big deal, because the benefits of lower drag and lower running resistance justify that minor imperfection.

So either make the car a bit heavier and/or install the capacitor and you will be all set after the Teflon application.


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## Dan Pierce (Jan 2, 2008)

Adding a capacitor is a great idea, but be careful. 

If you have 5 passenger cars with 2 prolights per car, then that is 10 capacitors and you just exceeded the capability of most systems to charge a capacitor. 

The fix is to use a resistor to charge the capacitor and a diode for the discharge path. This circuuit is in the Zimo decoder manual, and I believe I have seen it in other decoder manuals. 

Purpose of the resistor is to limit the surge current when the system is first turned on. A 100 ohm resistor on 25 volts will limit the current to 1/4 amp for charging. For multiple cars with leds, I would go to a higher value like 200 ohms and use a 1 amp diode.


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## Greg Elmassian (Jan 3, 2008)

Proviso: when I say "capacitor" I mean with a inrush limiting resistor. You don't really need the diode, since you are going to use a polarized electrolytic capacitor anyway.

Remember to calculate the wattage of the resistor!!











Greg


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