The earliest versions of the RR 4-4-0's had steel frames and pickup wipers just like the Bowker, but they later changed to a plastic frame with those sprung plungers. To be sure the current doesn't go through the plunger springs, my solution was to solder the ends of a length of stripped NWSL superflex wire to the back of each plunger. There's enough of a pocket behind them to dress the wire so it won't interfere with the plunger movement, which is critical because the springs in them are very light.
I soldered a lug I made from and spare bronze wiper to the center of the length of wire, which is then trapped between the frame and the axle cover by the cover screw. It makes for a solid electrical path from the plunger pins to the bottom cover and drawbar.
Nelson
"My latest project has been working over a group of 6 Rivarossi 4-4-0' s for a gentleman, as well as 3 J. W Bokers. He's decided that he really likes not having to hassle with dogbones, so they are all getting two piece brass tubing drive shafts and can motors. Think at this point I could write a small book on pick problems on these engines, and how to solve them...basicaly the problems, no matter what they act like come down to poor driver pickup. I'm find both the wipers and the little spring plungers just don't act like they are supposed to, and am just modifying them as a matter of course...the improvement in performance is simply amazing."
