Steam loco wiring for power pick-up

Discussion in 'FAQs' started by astapleford, Apr 28, 2008.

  1. astapleford

    astapleford New Member

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    Does anyone know of a place, or magazine article(s) that discusses the various ways steam locomotives are wired for power pick-up? I have 7 or 8 narrow gauge (HOn3) steam locos by various manufactures (PFM, Tenshodo, etc.) from the late 60's and the 70's.
    One or two have sound capability.
    Now, most are "plug and play", meaning connect tender to loco by way of a stud on the tender to the loco drawbar, which usually has a thin spring wire for continuity. Some have very small wires which need to be connected to the tender along with the drawbar connection, otherwise the loco won't run.....
    Are there any diagrams which show all the possible wiring techniques in magazines or on the internet, perhaps in this forum? It is very confusing trying to understand how these various wiring situations work!
    I wonder if sound units have loco power going thru them, hence, rewiring standard drawbar connections.
    Any info will be greatly appreciated! Thanks.
  2. steamhead

    steamhead Active Member

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    When you say "sound capability", I presume some of your engines are of a MUCH later vintage than the 60's and 70's....as sound as we know it today is probably no more than a few years old.
    Power pick-up and loco wiring are as varied as there are loco manufacturers around. Rather than try to figure out how each one did it...just keep in mind that motors and lights need a "+" and a "-" type of electricity. These can be picked up through the engine's and/or (if steam) tender wheels, or sometimes just through one set (either engine or tender). The easiest way to find out how your engines are wired up is to CAREFULLY take the loco and tender shells off, and follow the two wires coming from the motor to their origin. Once you've determined this, you can plan your installation of sound (or "silent") decoders.
    Hope this helps.

    P.D. Welcome to "The Gauge"...!!!
  3. doctorwayne

    doctorwayne Active Member

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    Most brass steam locos from the '60s and '70s had insulated wheels on the fireman's side of the locomotive (left side if you were sitting in the cab), and insulated wheels on the right (engineer's) side of the tender. The current path is through one set of uninsulated wheels, through the motor, then back to the rails via the other set of uninsulated wheels. Early models had a wire between the loco and tender, along with an insulated drawbar. The tender end of the wire was fitted with a terminal and attached to the tender with a screw. Later, the wire was eliminated by using a conductive drawbar, electrically isolated from the loco, with a wire in the loco leading from the drawbar to the motor. This allowed easier separation of loco and tender for maintenance, storage, etc. However, over time, the electrical connection between the drawbar and the pin on the tender can become worn, resulting in unreliable current distribution. I started adding plugs to all brass locos that I worked on for others, soldering a short length of rail joiner to the front of the tender, and a corresponding short piece of rail on a wire leading to the motor. This was in addition to the drawbar connection, and still allowed relatively easy separation of loco and tender, with improved electrical conductivity. I now use simple plugs available from most electronic supply warehouses - you cut off the number you need, solder wire to them, and you're all set. Most brass locos would require one male and one female plug, although the loco shown has current collection from both sides of the loco and of the tender, so two plugs were used. The red dot ensures that proper polarity is maintained.
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    Basic sound was available in some locos through a circuit board, usually in the tender, along with a speaker, activated by a cam on one of the loco's drivers acting on a wiper. I think that it was pretty much confined to basic loco "chuff", though, with no on-board bell, whistle, etc. I do recall hearing an S scale loco with these functions at a train show in the '70s, although I believe that the additional sounds were from below the layout - ie not on the loco itself.

    Wayne
  4. astapleford

    astapleford New Member

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    Thanks, guys! Yeah, I removed the boiler from the frame/drivers. I found a mess of wires going to a circuit board which was a distribution board to headlight, and sound unit (in tender). In doing this, I forgot about the piston guide and the two rods on each side.....they came out, and was a real pain to get back in. But, after I accomplished that, I found the "return" side of the motor, touched a wire to it, and then to the "return" side of the track, applied power on my test track. The loco took off, and all the rods worked as they are supposed to......whew! It is a Westside K-36, probably from about 1982)
    So now, I am going to solder a wire (probably 30 AWG?) to the motor terminal and run it to the tender female connector. But, for simplicity, I would rather solder the wire to the drawbar, making sure the drawbar is insulated from the loco frame, or both, as Wayne suggested.
    I will let you know how it all comes out. This is an exceptionally good running loco, and want it to work well after I complete the procedure!
    Thanks again.
    Al
  5. steamhead

    steamhead Active Member

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    Hey..!! Good to hear you made'er move..!! Before you do any running, make sure you clean out any old oil & grease and do a lube job. Then you'll be all set to go....