South Bend Signal Co. automatic block signals

Operating block signals with infra-red block sensors
signals4
Kevin Strong
Automatic block signals
South Bend Signal Co.
2303 Creek Rd.
Niles MI 49120
Price: $80 each
Website: www.sbsignal.com

1:26 scale, automatic, radio controlled, operating block signals with infra-red (IR) block sensors; styrene-and-brass construction. Dimensions: Height, 10"; width, 1" (exclusive of track sensor); length, 31/2" (including base)

Pros: Prototypical appearance; available in different styles to match prototype practice; LEDs visible even in bright daylight
Cons: Block signal shows “occupied” (red) only as long as the train is directly over sensor
signals4
Kevin Strong
There’s a “cool” factor to automatic signals on a railroad. Watching a train pass a point and seeing the signal go from green to red adds a sense of realism that static signals just can’t match. Toward that end, South Bend Signals makes signals that do just that—as a train passes the signal, the light changes from green to red; after the entire train passes, the signal goes to yellow, then back to green. (These signals were reviewed in the December 2009 GR.) They worked well but could arguably be considered cosmetic, since they only indicated what was happening right next to that one signal at any given time.

South Bend’s new signals up the ante a bit. In the real world, when a train is in one “block” of track, the signal controlling that block turns red, alerting any train in the previous block to stop. When that signal is red, the signal in the block before that one displays yellow, alerting any approaching train that there’s a train ahead and it needs to slow down. (If you’re the Pennsylvania Railroad, you wouldn’t use colors but horizontal, diagonal, and vertical rows of lights.) South Bend’s new signals use radio transceivers to communicate with each other so that, when one signal changes, it also changes the previous signal.

The signals are stated to be 1:26 scale. Not having a drawing of the specific signal South Bend is modeling, I’d say they’re in that ballpark. Our review samples stand almost 10" tall, which is 260" or about 22' in 1:26 scale—reasonable for a trackside signal. The “equipment cabinet” at the base of the signal may be oversize from a prototypical standpoint but it has to be large enough to contain the control electronics and the battery, so it couldn’t practically be any smaller. It’s not unreasonable and blends in with the scenery.

The signal is available in five different styles; you can choose the style that’s most accurate for your specific prototype (including the aforementioned PRR). Construction is sturdy and the detail is good. The LEDs are quite bright, visible in daylight without difficulty when viewed from straight on. They’re directional, though, so from angles greater than 20° to either side, it may be difficult to tell what color is showing in bright light. If that’s an issue, a little sandpaper to scuff the end of the LED will diffuse the light for better visibility.  

Each signal has a power switch and room for a battery inside the case. It can be powered either by a standard 9V battery or a rechargeable 3.6V NiMH battery (available from South Bend). The signal itself is weather-resistant but not weatherproof. The manufacturer recommends covering them or removing them when not in use to prevent water damage.

Operationally, the signals communicate with each other via a 2.4gHz transceiver. The signals are “paired,” so that one signal talks to the previous one. Multiple signals can be daisy-chained together, so signal B talks to signal A, then signal C talks to signal B, and signal D talks to signal C and so forth. Pairing and placing the signals is covered in the instruction manual. It took me a couple tries to get the signals to pair properly but, once they did, they worked reliably.

The sensor that detects the train passing the signal is a small, weatherproof affair that’s designed to be permanently attached to the track. It’s black, low profile, and fits neatly between the ties. It contains an IR emitter and receiver. As the train passes over the sensor, it reflects the IR light down to the receiver, which triggers the signal.

The sensor plugs into the signal; the length of the arm puts the signal 31/4" from the center of the track, which should be adequate clearance for most models. However, if you occasionally run 1:20.3 or 7/8" scale, narrow-gauge equipment, they may bump as they pass. (Such signals were a rarity on narrow-gauge lines so it’s unlikely to be an issue for anyone modeling a specific prototype and sticking to a given scale.)

I placed the signals on my railroad to see how they worked. While I don’t have specific blocks, I do have three different towns, which plausibly might have had signals controlling trains coming in and out. I set the signals up (one pair) and ran the train by them. As the train passed the first signal, the light turned from green to red. Since there is no signal “behind” the train, that’s all that happened. The signal in front of the train remained green. Once the train passed the first signal, that signal turned back to green. When the train reached the next signal, that signal turned red and sent a radio message to the first signal to change to yellow, which it did. Once the train passed the second signal, that one changed back to green, sending a signal to the first signal to likewise change to green.

I will say that the communication between signals is very cool. What I didn’t like was that there was no delay built into the signals once the train cleared the sensor. As soon as the caboose cleared the signal, it turned green. In the prototype world, that signal would stay red until the train entered the next block, at which point it would change to yellow. With these model signals, the first signal is yellow only while the train is physically passing the second signal. Unless your signals are closer together than the length of your train, there will always be times when the signals are green, even though there’s a train in that block or the block ahead of it. The older-style signals from South Bend have a programmable delay so that you can set the time that elapses between changing from red to yellow. I have to wonder if something like that could be built into these signals to give the train time to travel to the next block before the signal changes from red to green.

When I think of “block control,” I think in terms of long stretches of track and signals that detect a train at any point along that stretch of track. By that measure, this system is not exactly “block control.” It detects a train at a specific point on the railroad. The operation and feedback from one signal to the next is cool, but I don’t know that, as an operator I could really trust that a signal that’s showing green to mean “all clear ahead.”

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