graphite to improve switch point electrical conduction

[Texas Zepher]

gregc

it's obvious that the point rail of a turnout contacts the appropriate rail to power a turnout frog, but that electrical contact is unreliable over time, most likely due to corrosion....1) would graphite on the surfaces that make contact improve conduction between the point and stock rail, as well as reducing corrosion?

Warning Warning Warning....   Graphite conducts electricty really well, and since it is powder with one spark or short circuit through it, it will combust.  At our club someone thought graphite would help the conductance of the contacts on our turnout motors.  They were the slide type where a "finger" rubs down a trace as the motor moves. It was the first and only time we had to use the fire extinguisher.  It was almost explosive combustion.

[retsignalmtr]

I don't know if Graphite is a conductor or insulator. If your rails are Nickelsilver it won't be caused by corrosion. I use a plastic or brass wire wheel in a dremmel tool to clean the mating surfaces between points and stockrails every so often. Applying graphite and controlling it's migration into everything depends on if it is a liquid or powder. You must be careful that a liquid graphite does not have chemicles that would damage plastic parts on the switch and blowing powdered graphite scatters it around.  Atlas makes a conductive lubricant that I sometimes use on the pivits that connect the points to the lead rails on my switches. But then oils attract dust.

I used liquid graphite with a Laquer base on prototype switches to lubricate the points. One problem there was applying too much over several months causing a buildup of the graphite and throwing the points out of adjustment and keeping the points slightly open until you had to chisel it off and reapply. 

[rrinker]

 Well that's not totally 'obvious' since it depends on the turnout. The BEST way is for the frog to be isolated and powered via contacts or, of using DCC, an automatic device liek the Tam Valley Frog Juicer. Many turnouts these days are made that way, with the two point rails insulated from one another and jumpered to maintain the same polartiy as the adjacent stock rail. This eliminated and chance of wheel backs shorting and allows the point ot stock rail distance to be minimized for the open point, making a more realistic looking turnout. Handlaid turnouts made with the gaps cut like the Fast Tracks diagrams end up beign wired liek this as well (even if you don;t use their jigs to make them). Atlas Custom Line turnouts are like this, today. Thecurrent production Walthers turnouts are also like this.

 If you are using older turnouts that do indeed rely on point to stock contact for power, grpahite may help, for a time, but it's not goign to last or be reliable int he long term. Many commercial turnouts that were wired this way have a small tab on the points that slides udner the stock rail for a more positive contact, but even this is subject to failure. For reliability, the points and frog shoudl be powered via a feeder and contacts, however in the case of turnouts liek this you have to be careful that the opposite polarity contact ont he siwtch motor (either powered to manual like a slide switch) does not make contact with tsay the diverging side while the point is still in contact with the straight stock rail, or you will have a short. This is often an issue with the Tortoise and is the origin of a mode where the copper contacts inside the Torotise are cut back so as to make contact only at the extreme ends of travel.

 Forget "DCC Friendly" and allt he words bandied about, it's this issue, and the unreliability long-term of the point to stock rail contact, that makes turnouts like these not worth messing with. It so happens that the ones called "DCC Friendly" are wired like my first example, and long term will be much more reliable electrically regardless if you use DC or DCC, so if purchasing new, consider this.

                      --Randy

 

[gregc]

it's obvious that the point rail of a turnout contacts the appropriate rail to power a turnout frog, but that electrical contact is unreliable over time, most likely due to corrosion.    there's 2 parts to this question

1) would graphite on the surfaces that make contact improve conduction between the point and stock rail, as well as reducing corrosion?

2) will the graphite spread if it is properly applied only to the sides and not the tops of the rails, shouldn't it ever contact the wheel?

greg