Wednesday, April 20, 2011

Point jumpers

Rule of thumb:  If it doesn't have a wire soldered to it, it's unpowered (if not now, then soon, and probably at an inconvenient time).

When I first started using Atlas O turnouts this rule was proven once again.  I started having trouble with the Weaver GP38-2 I had at that time occasionally stalling on my Atlas #5 turnouts.  (So far I have left my frogs unpowered).  On unmodified Atlas turnouts there are two ways the point gets powered - through the hinge, and from contact with the stock rail.  If you've painted the track, or ballasted and gotten glue in, or just aged it enough to get dirty either or both can fail.

It turns out the GP38-2 is exactly the right length so when one truck is completely on the (unpowered) frog, the other is completely on the point.  Since I hadn't thought to solder anything to the points, the inevitable happened and sometimes a point would be jiggled just right so it wasn't making contact, and the loco would stall.

My solution was to solder jumpers between the points and closure rails.

I made my point jumpers out of 1" long pieces of #24 stranded wire.  You want to center it on the point hinge, a solder the last quarter inch of each end to the rail leaving the middle half inch free and not saturated with solder.  It's very important to make sure the middle 1/2 inch is free from solder so it maintains it's flexibility allowing the points to move freely.  My switches with point jumpers installed will still stay in either position by themselves with no ground throw holding them there, and still flop back and forth just as easily as ever.

I made a clamp to hold the wire in place and act as a heat sink to keep solder from wicking into the middle of the wire.  I cut three ~2" pieces of 1/16 x 1/2 aluminum.  These will form a sandwich - one piece will go on the gauge side of the rail, the middle piece between the rail and the wire, and the last piece outside the wire.  File grooves on the middle piece to help hold the wire in place on one side, and to help position the clamp on the rail head on the other side.  The exact placement of the grooves isn't critical - you want the groove for the wire to end up about centered on the web of the rail when the other groove is on the head of the rail.  I drilled a hole through all 3 pieces and put in a screw with a wing nut to make it easier to use.  The screw head is glued in place so the wing nut can be easily tightened.

Point jumper clamp.

The rail goes in the left side, the wire in the right side.  The next picture shows it holding a wire in place:

Point jumper clamp in use.

I use a resistance soldering iron to solder on point jumpers and track feeders.  I will admit to a moment of confusion when I just couldn't get a jumper soldered on well with the resistance unit.  Obviously the aluminum jig conducts electricity quite well, so most of the juice was going through it instead of the solder!  Duh!  Putting a piece of paper between the clamp and the rail solved that problem.  I left the paper out of the above pic for clarity.

Here's a turnout with both point jumpers soldered in place.  Even unpainted and sticking out they're a lot less conspicuous than they appear in the top down close-up photo below.   After you paint the jumpers, the rail and fold the jumpers down right next to the rail they virtually disappear.

Finished point jumpers.

The rest of the rails in the turnout are bonded to the two stock rails via copper strips that appear to be soldered to the bottom of the rails.  This is true for the closure rails and the two rails on the other side of the frog.  So once you've added the point jumpers, you can power the entire turnout with just two wires, one to each stock rail.

1 comment:

Unknown said...

I have a layout with Peco Code 55 turnouts in N Scale. Any thoughts on whether I can use the points jumper system?