Model Railroading > An interesting problem .....solved.

A friend on mine has a layout with Atlas #6 switches and uses DCC. No big deal, but, he also runs Bowser steam engines. As we know, the Atlas switches are insulated, and Bowser locos jerk and hesitate over the frog. I told him that Atlas has a relay that will power the frog. After refreshing myself with Atlas switch control devices, mainly the snap relay, I was ready to power the frogs. I looked at the Atlas instructions and realized that this was not going to be easy, because the instructions were for analog wiring purposes, and I was dealing with DCC. Yep, DCC + Atlas switches + Bowser locos = real big headache! Sure, the instructions were straight forward and easy for analog. With analog, you are changing the polarity with the transformer. With DCC, you have constant voltage in the rails, thus, the track polarity does not change when you reverse the loco. When wiring the snap relay, as per the Atlas instructions, the locos cruised over the frog just fine. When I reversed the switch and ran a loco over the frog, boom, big time short. So, I needed to figure out how to wire the frog and reverse the polarity using an Atlas snap relay. After a few different wiring attempts, I found that the pic below is what you need to do. It works perfectly. Let me explain the pic below:

*The terminals labeled "common" will be your track power. One terminal for A rail and one for B rail. ( North or South rail respectively)
*Next, you will need to solder or screw a wire to the frog. On Atlas Custom Line switches, holes are provided for this. The "frog wire" will be attached to the side of the snap relay that corresponds to the rail.( A or B, North or South )
* Then, to allow the polarity to reverse, connect a jumper wire opposite of you frog wire.***SEE THE PIC BELOW***

I hopes this will help somebody out there.

R.Geiter
Lancaster, PA

This interesting solution to an Atlas switch/Bowser loco stalling situation is only half the answer. It's also, and I'd wager to say primarily, a result of the Bowser loco design, if it was built as designed with no extras.

Like most older-design steam, Bowser steam engines pick up current from the left-side tender wheels (the right side are insulated) and the right-side loco drivers and possibly the pilot and trailing trucks (the left side are insulated). That bare-minimum electrical pickup arrangement makes it very easy for a stock loco to stall on a piece of track where there's any interruption of the current flow, possibly aggravated by local dirty trackwork. The original poster didn't say what kind of Bowser loco was having problems, but an insulated-frog switch and a smaller loco, like an 0-4-0 or 0-6-0 switcher, are an almost sure-fire combination for stalls and even larger locos can have problems.

One very functional solution is to add electrical contact wipers to the right-side (insulated) tender wheels and connect them to the loco's chassis (right side pickup) circuit. Extra contact wipers added to the loco's left-side (insulated) drivers can also be wired to the tender's chassis (left side pickup). This can effectively more or less double the loco's electrical pickup points and virtually eliminate stalling on bad track or switches with insulated frogs. I add wipers like this to all of my steam projects -- no diseasles here -- and it helps a great deal with smooth, reliable performance.

For complete details about this kind of procedure, see my story, "Contact! The Key to Reliable Performance" in the March 1995 issue of Model Railroader, pg. 112-114.

Jeff Johnston
Modeling the Sugar Pine Lumber Company/Minarets & Western Railway circa Sept. 1927