To Trolley Pole Reverse Or Not To Trolley Pole Reverse.

That is the question.

Exploring the two methods of wiring a trolley. The "cool" method or the more practical method.

(NOTE: This post was written when when the layouts were wired for standard DC (Direct Current). But with the advent of DCC (Digital Command Control) Trolley Pole Reverse is no longer an issue. Cars are wired for "Trolley Pole Forward" as shown below. -Dandy 2020)

The question we get the most when the Southern California Traction Club displays its modules is "are the trolleys getting their power from the wires?". Not only are the guests pleased when we inform them that indeed they are, but we will also do a little demonstration of "Trolley Pole Reverse" that guests take a delight in. It doesn't take long for a trolley to come by. So I'll put my finger lightly under the overhead wire so that as the car comes by, the pole will disengage the wire and the car will roll to a stop. I'll stow that pole under the hold down hook and explain that "one pole is wired to one pole of the motor, and the other pole is wired to the other pole of the motor". Lifting the opposite pole to the wire, the car jumps to life and continues on its way ~ in the opposite direction. Guests are thoroughly impressed.

But lately we at the club have been discussing reliability. As all model railroaders know, the toughest electrical continuity to maintain is the contact between rail and wheel. The slightest obstruction will cause a stall. Stalls are no fun. With traction modeling not only is that problem made double with the tiny contact between the trolley shoe and overhead wire but triple so with the just as critical contact between the stowed pole and the hold down hook.

When a car stalls, its usually the tiny connection between the trolley shoe and overhead that's been compromised. A gentle tap of the overhead is usually enough to reengage to shoe to the wire. If that doesn't work then its probably the wheels, nudging the car forward a tad should fix that. If that doesn't work then a wiggle to the front pole might invigorate that contact. If that doesn't work... well, you get the idea. It gets a little frustrating. So eliminating weak spots like these just makes things run a little smoother. But eliminating the contact between the rails and overhead isn't feasible. But that connection between pole and hold down hook can be addressed.

With Trolley Pole Reverse, one trolley pole is wired to one pole of the motor while the other trolley pole is wired to the other pole of the motor. Whichever pole is in contact with the overhead will supply the positive charge to the motor. The other pole is in contact with the hold down hook completing the circuit by providing ground. This method requires good spring tension to press the pole up against the hold down hook and a clean connection between the pole and hold down hook. A little contact cleaner fluid is helpful here as well.

Though I've never heard it called this, I'm calling this method "Trolley Pole Forward", as opposed to Trolley Pole Reverse. This method eliminates the contact between the pole and hold down hook, providing a bit more reliable operation. This is particularly useful in a DCC environment where a car can be reversed without reversing the polarity of the rails and overhead. We simply tell the decoder to run the car the other way.

I think it all comes down to preference. On a point to point operation, Trolley Pole Reverse might work best. For a "roundy roundy" operation, Trolley Pole Forward might be preferred. On a DC layout, I think Reverse could be the way to go. On a DCC layout, Forward could be it. I don't know. But I think once my layout gets rolling, time will tell which I prefer. Yes sir! Time will tell!

Dandy

(Edit- Time has told! Yes- on a DC layout, "Reverse" is a good way to go. On a DCC layout "Forward" is the way to go. -Dandy 2020.)

Birney Project ~ Installing the Decoder

"You've got too many damn lights in that thing!" George Huckaby.

I may have blown out all my lights, but the Southern California Traction Club has blown out entire decoders trying to get these things to work properly in trolleys running under live overhead! As a grateful benefactor of the trials and tribulations that the SCTC went through, I drew the following schematic based on the findings of the club (clicky to make biggy) :

This schematic illustrates how the TCS M1 decoder is to be wired in my model of SDERy Birney #301. The model has 10 (yes 10!) incandescent light bulbs in it, five of which would be lit at any one time (If I had to do it again, I would rather use LEDs in conjunction with fiber optics). The schematic also includes the necessary resistor that was so agonizingly missed the first time. I have the choice of having one 1 watt 100 ohm resistor* on the white wire and another on the yellow wire. Or one big 2 watt 100 ohm resistor* on the blue wire. Considering how big the resistors are (they are bigger than the decoder!) and how hot they get (and they get hot!), I decided to go with the one big resistor. BUT! That means not all the lights can be lit at the same time! Or else "poof"! Out go the lights yet again! That's a disaster waiting to happen, I'm going to have to be damn careful. Yes sir, Damn careful.
* Note: The value of the resistors were determined by some of the club members using wizardry and gadgetry that I'm not familiar with.
Bonus! Check out the March 2010 issue of Model Railroader for a resistor selector device on page 26.

First, the decoder is mounted to a piece of 3M 4011 Double-sided Mounting Tape, which in turn is mounted to the ceiling of the model.

Then comes the surgery. Two wires from 10 bulbs = 20 wires, plus 7 from the decoder, plus two from the motor, and two from the connector. Let's see, that's... 31 wires that all have to make specific connections with each other and the resistor, all in an itty bitty living space!

In this photo, we're looking through the cutout in the floor to the cutout in the subroof. I'm trying to keep the decoder (which also gets hot) as far away from the hot resistor as possible. So the decoder(right) is mounted to the roof through the subroof cutout. On the left side of the cutout I mounted a weight (simply for better running). The resistor (left) is glued half on the subroof and half on the weight. Hopefully this will help dissipate all that heat. There is officially no more room for anything else in this model!

Everything tucked up into the ceiling pretty nicely, preserving the seethroughableness of the car, even at this low angle. Good enough for me. Next stop will be the programing track to program the decoder. Then I'll officially take my place among the ranks of DCC-ers. Yes sir! I'm getting with the program!

Dandy

Birney Project ~ Wiring for Trolley Pole Reverse

Fortunately, the Birney cleaned up nicely from the April fools day disaster ;-P. So now we can continue with the wiring. I'm going to use a nifty technique known as "Trolley Pole Reverse":

Trolley Pole Reverse wiring is used with live overhead. The direction of the trolley is reversed by simply switching poles, no need to switch polarity in the track! The way it works is; one pole is wired to one of the motor leads, and the other pole is wired to the other motor lead. When one pole is up in contact with the positive overhead, the motor lead it is wired to becomes energized with the positive electrisicles. The other pole is down making a connection with the holddown hook on the roof. That hook is part of the metal car body that is energized with the negative electrisicles from the wheels in contact with the negative rail. So that pole is energizing the motor lead its wired to with the negative electrisicles, making a circuit! Then, switch the position of the poles so the first is down and the other pole is up, the polarity of the motor leads are reversed and the trolley runs in the opposite direction! Cool huh?

Utah Pacific #CLU-96 Constant Lighting Kit wired in series with the motor provides 1.5 volts for reversing headlights and taillights as well as constant lighting for the destination board and route number signs. I had to omit the interior lighting, the unit is at capacity with the 7 bulbs its already lighting. Maybe someday I'll be able to figure out how to light the interior but, if I was to do it all again, I would go with LEDs. They last much longer, I'm not looking forward to fishing out a burnt out bulb out of the spaghetti of wiring shown above. The bulbs are glued in place with Elmers White Glue. Elmers is also used to glue the wires to the ceiling so that the dont hang down in the windows. Elmers hold really well but is also easy enough to remove.

2 Pin Micro Mini Connector from Miniatronics (Code: 50-001-02) allows the motor/truck assembly to be detached from the body for maintenance. One pin is wired to one trolley pole and the other pin wired to the other pole/constant lighting module. The negative charge from the rails transfer through the mounting screws to the trolley body and hold down hooks.

Add some power and "bling"... yessir! "Bling"!

Dandy