Copper rollers on ZW

Both copper and brass oxidize besides having no lubricating properties like graphite.

The slight initial benefit is a lower voltage drop would be lost is a few hours of operation.

Pete

They will oxidize even when not is use. Arcing and heat would only speed up the process. You never see plain brass or copper contacts. They will be plated with some other metal that resists oxidation.

They wouldn't be hard to make if you wanted to try one.

Pete

Since we are talking optional metals for ZW rollers, how about aluminum and/or nickel???  And what about the old copper brushes that were originally used in post war locomotives instead of the new cheaper carbon brushes that wear down twice as fast.

I've tried to find copper brushes with little to no success.

Did Lionel actually use pure copper brushes? All of the ones I have seen are a copper/carbon mix. Same with the ZW rollers, at least the better ones. You can still get the composite items at the better Post War parts sources.

BTW aluminum oxidizes even faster than copper. 

Pete

There would be a problem with dissimilar metals and which metal is electrically anodic. You want the rollers to be anodic I Believe.  Aluminum is bad and Nickel is too brittle.  Silver or gold is about it.

Original brushes were copper mesh (generally prewar) or a copper/carbon matrix sintering. They were really good!  But with the cost of copper escalating we get what we get nowadays.

I wouldn't want copper rollers in my ZW, or brushes with an extra high copper content in my motors.

I want my rollers and brushes to be softer than the windings / commutator plate that they are contacting. Rollers and brushes are disposable / renewable items, its ok for them to wear.

I guess gold might be OK, but what would a set of rollers cost?

I think Lionel's engineers did a pretty good job with the ZW, I'll stay with their original design.

Mr. Norton has apparently never looked inside a Lionel transformer, as copper and brass are used extensively as contacts. Yes, they tarnish but that seems to have little to no effect on their conductivity. BTW, the conductivity of metals is 1) silver, 2) copper, 3) gold, and 4) aluminum. Graphite, which is essentially carbon, doesn't even make the top ten.

I made some copper rollers for my KW years ago, and have had no problems with either oxidation or wear of the windings. Aside from their greater durability than the graphite ones, I will concede I see no difference in the way the transformer runs trains.

Also, I invite mr Norton to construct a set for himself. It isn't as easy as you'd think, and if you don't have a lathe... well, good luck!

Are you confusing contacts (two separate pieces of metal that touch via spring force) with buss bars? Other than the circuit breaker where are these "contacts" used in the ZW? As for machining rollers, a five minute job including time for a cup of coffee.

Pete

Silver tarnishes far too easily to make good contacts, this is primarily why gold/gold plating is used, particularly in low voltage uses like stereo/video equipment and in micro chips.  The dentist that was making the gold rollers was charging around $350 a pop back when gold was selling around $550 an ounce.  Hate to see what these would go for today.

btw, this was written up in model railroader and the gentleman indicated the zw was able to handle the full 180 watts output without the usual excess heat.

Pete,

I'm thinking of the whistle/direction switches; also there is brass to copper connection where the roller arms attach to the shaft, for example. All Lionel transformers (postwar anyway) use brass and/or copper for the directional control, and the ones that don't use rollers have a copper wiper directly on a copper winding for speed control. They get plenty of abuse and somehow manage to work. Another example is the small motorized units (like the gang car and derivatives) also use copper/copper contacts for their reversing mechanism.

There is no plating or coating on any of these. In fact, the only place I can think of at the moment where plating is used is on the sliding shoe pickups of older steamers, and that doesn't usually last very long.

Regarding the copper rollers, please tell us all exactly how you can make a set of rollers in 5 minutes. Do you think everyone has a lathe at home? Even if you are a master machinist with CNC it would take longer than that to set up the equipment. If you're talking hacksaw and hand drill I'd love to know how you get the rivet holes centered and a consistent thickness from piece to piece.

The reason carbon is used for contacts and motor brushes is that carbon has no liquid state.  When it is heated it goes from a solid to a gas.  The advantage of this is the contacts are less likely to weld and it does not leave molten balls or splatter when it has been arcing.

quote:

Silver tarnishes far too easily to make good contacts

According to my understanding pinball machine relays used silver contacts.
Didn't Lionel use silver plated materials for e-unit drums and contact fingers?

Perhaps a silver alloy

Silver reacts to the sulfur in the air.  If there isn't much in the way of sulfur it won't tarnish.  Silver has a low oxidation rate and it doesn't arc when breaking contact but is is extremely soft.  I believe most of the contact points use alloys of silver or silver plating because it is pretty soft.  Some of the alloys are pretty nasty, e.g.. cadmium.  Home recycling would be a bad idea.

The 5 minutes was the time to make one roller in a lathe. We are talking putting a round bar in a chuck or collet, drilling a center hole and cutting it off, no? Its been a few years since I rebuilt a ZW so maybe the sides have to be tapered. Still, NBD. 

Before I had any machine tools I would have used a drill motor to do this. Much more time consuming admittedly but it could be done by someone who wanted to find out if copper provided a benefit over copper/carbon.

Pete

The advantage of using silver as a contact material is that it conducts electricity as well as copper, it is a natural lubricant, and silver oxide is as conductive as silver.  Silver contact tips may be a powdered metal mixture of silver and tungsten carbide.  Lionel had a problem with wear on the worm wheels of the post war motor units.  Some replacement worm wheels were silver plated to act as a lubricant.  Silver alloys are used as Babbitt on some high speed, high temperature applications.

IMO, the HUGE issue with using copper, silver, or gold rollers on the ZW or KW is when you short adjacent turns on the core, you get some really healthy current in the shorted winding!  With the carbon roller, it tends to "burn" enough away to have a higher resistance connection between the windings.  I personally think that a copper roller would pretty quickly turn out to be a major problem.

Gunrunner,

How then do you explain the transformers that use a wiper arm instead of rollers?

There's no way the contact point of the wiper sits on top of only one winding at a time. Plenty of adjacent contact and no trouble!

I'm going to make a set of zinc rollers this weekend and see how they work out.

Well, at least for the 1033, at certain settings I hear the transformer humming louder than normal, I assume that's when the adjacent turns are shorted. They also seem to be mostly lower capacity transformers.

It's certainly not good to have a turn on the transformer directly shorted, of that I am certain.  I think I'll stick to the carbon rollers, I suspect the folks that originally designed the transformer had a pretty good reason for them.

I've read here that using copper brushes give more wear to the motor and the 

carbon wears less, and saves our trains.

Tin