General ideas about electrical power pickupWhen I first started in the hobby, I saw all kinds of power pickup systems. At that time, I believed that the ultimate power pickup was ball bearings. But as I learned more, I discovered that for heavy current applications, ball bearings are not the right choice.First I will go over ball bearings for light current applications, like lighting cars, and auxiliary power pickups for locos, like a steam tender in addition to the locomotive pickups. Dual ball bearing wheels The best made in my opinion are the LGB. These are dual ball bearings, i.e. bearings on the axle between the axle and the wheel, but they are larger in diameter than many freight car wheels. Luckily, they make the same diameter wheels in "normal" axles. So one pair of ball bearing wheels and one pair of normal ones are perfect for a lighted caboose. (I'll add the part numbers). Unfortunately LGB is now part of Marklin who is in bankruptcy, so prices are very high, and availability is low. They are hard to find, expensive, and shiny silver, hard to darken. The centers are plastic, and the outer part of the wheel is metal. But they are the best electrical pickup I have used.Train-Li has imported some dual ball bearing wheelsets that appear to be of very high quality and are all metal. I will have to try these, as Train-Li is known for high quality products.Aristo also makes dual BB wheelsets with pickup connections. They are fine. You can get them blackened or silver. They are not quite as high quality as the LGB, bearings or pickup quality or wheel plating. They are probably your best choice now. Again, they have a slight size variation from other wheels, but no exact diameter match with other Aristo wheels. Weird. I have several sets and they are ok, but the older ones are losing conductivity.I believe Gary Raymond also makes dual ball bearing wheelsets with power pickup. I will have to check them out.Carbon or metal brushes This is one solution that has pluses and minuses. On the positive side, they can take higher currents. On the negative side, they wear, need to be kept clean, and really should be lubricated with a special lube on a regular basis.Unless you are careful and have the right lube (motor commutator lube), my best advice is don't lubricate them. They may squeek, and you should probably live with it. Anything put on the wheel backs to lubricate them almost always results in goo, more friction, grit and crud sticking to the wheel, and gumming up the spring loading mechanism to keep the brushes in tension.The brushes normally exert a fair amount of drag on the wheels. Brushes in poor condition or improperly lubricated can cause damage. Some people cut a few loops from the springs to help offset this, but the result is also less electrical pickup. See the picture below about the results of increased friction, look carefully at the groove worn in the wheels. Look at the lower left wheel in the picture below. Many people will disagree about using ball bearing wheels for high current applications. The problem is part of exactly ball bearings have such low friction. They have low friction because the contact area is tiny. Smaller contact patches where things move is less friction.This is why trains roll so efficiently, the contact patch between the wheel and the rail is very small. Unfortunately, this small contact patch is exactly what you do NOT want for electrical conduction, and high currents will pit the balls and races. My Aristo units are going south after a few years with a 1 amp motor sweeper car running from 2 axles.For a locomotive, if you can have many pickups, then some can be ball bearings, like making all 8 wheels pick up power on a steam tender, but you need to pick up half of the current from the loco too.