Wednesday, September 28, 2016

St. Clair Sub Signal Install - Part 4 (Phase 3 - Basic Interlocking)

Continuing with our signal installation series, in this post we will focus on basic interlocking using the Azatrax TS2 signal circuit. At the same time we will add another signal block to the Michigan Interstate St. Clair Subdivision. 

Readers: The signals and signal systems that I will be reviewing and installing in my Layout How To series were provided at no cost by Azatrax LLC. However the selection, installation, operation, and opinion of these signals and systems are 100% my own. 

If you have been following my signal install series, you probably noticed that each post we build upon the previous. The best part of building upon each phase is the basic process gets easier while we add a new piece that is a little bit more work. 

MCIS 3830 knocking down the signals at east end of Upper Huron. In this post we will walk through the install of these signals, TS2 circuit, and adding the ability to "interlock".


1 - Azatrax TS2 Circuit Kit
            (Kit includes the board, 2 sets of IR LEDs and IR Receivers with wire leads)
       We will use the 1000 ohm resistor for this install
2 - BLMA 1038 Block Signals
1 - Single Pole / Single Throw Push Button Switch
1 - Momentary Push Button Switch

In addition to the ordered components, you will need the following items:
- 3/16 inch #12 Drill Bit
- Small Wire Stripper
- Solder Iron / Rosin Core Solder
- 28 Gauge Wire - Solid in at least three colors
- Signal Tester (Used for BLMA signals which are made with magnet wire)
- Heat Shrink Tubing
- Hot Glue Gun

We start by marking where we are going to drill for the signals and sensors that will be installed in between the track.

 Signal installation between the east wye switch at Upper Huron and Quinacassee Creek Bridge.

Drilling complete - ready to clean up and begin installing LED sensor and receivers..

Installing the LED sensors through the track is done the same way completed in our part 2 - phase 1 post. It is important to only have one tie space (two ties) between each of the holes drilled at 45 degrees for the sensors. 

 For this install I decided to install the TS2 on the fascia for easy access and maintenance. The wooden box is from Hobby Lobby for around $2.00 and after cutting the back off on a tablesaw, it would fit nicely on the fasica. It is important to ensure plenty of room if you decide to mount the TS2 in a control box.

 Marking the inside outside of the control box I proceeded to drill holes for wire access and TS2 mounting. 

 TS2 installed on fasica, ready to begin fishing wires from LED sensors through from under layout and connect into TS2.

East/Westbound LED Sensor / Receiver and power connected. 

Test - Test - Test with a variety of equipment before moving on to signal install / connection.
 MCIS GP38-2 #3830 operating at walking speed over the east and west sensors of TS2 #6. Locomotive fuel tanks can cause sensing issues, ensure you test multiple variations and adjust as necessary. 

Intermodal wellcars, tank cars, and covered hoppers put the sensors through its paces.  

Once you feel confident and the sensors properly detect without issue, then it is time to move onto signal install.


 Threading the signal wires down through the foam board, under the layout, and through the fascia access holes we prepare to trim down the wires, strip, and connect to TS2.

 TS2 Wiring complete - remember to keep it neat!

 East and Westbound signals at East Upper Huron protecting between the Upper Huron and Lacey DTC blocks. 


A quick primer on the function of interlocking at Upper Huron. On each end of Upper Huron is a east and west switch that connects to the Port Belle Sub. When the switch is thrown reverse allowing a train onto either leg of the wye we want the signals on each end of the block to display a "stop" telling the crew that a switch in this particular signal block is lined against the main. In the prototype throwing a switch like this in ABS territory would shunt the signal to "stop", so by using the interlocking function we can represent this same concept. Since the switches are manual, we have to help the system know the switch is reverse and we will do that using the S1 "On-off" SPST switch. Additionally once the train has moved onto the Port Belle Sub and the switch is returned to normal we use the S2 "Momentary switch" to clear the block bringing the signals back to "proceed" indication with the train now in the clear. Remember our ABS signals only display block occupancy, it is still the job of the dispatcher to issue track authority via Direct Traffic Control


 West wye switch in the town of Upper Huron. The concrete ties are the St. Clair Sub main that heads east to Grays Lake. The diverging track to the left is the wye west leg to the Port Belle Sub.

East wye switch at Upper Huron near the sugar beet plant. You can see the main concrete ties coming around from the west switch and wye east leg diverging to the right. 


Azatrax provides in each installation guide for the TS2 and online, diagrams for wiring up the TS2 for basic interlocking. In our Michigan Interstate example we have two switches; one for the east leg and one for west leg of the wye. Both switches fall between the TS2 #1 and TS2 #2 so all we need to do is wire in a simple SPST push button switch for S1 and a momentary switch for S2.

In previous installs we have linked TS2s using "LE" to "LW" and "C" to "C". This install is no different as you can see in the diagram below those connections are still there. The difference is the extra set of wires coming from "LE" and "C" on TS2 #1 that split and go to on-off switch S1 and momentary switch S2. This extra set of wires drive the TS2 to operate in interlocking mode between these two TS2s only. 

Basic Interlocking Diagram courtesy Azatrax 

The specific example on the Michigan Interstate. S1 in foreground, S2 in background awaiting wire connections. These were install directly on the fascia using a 1/2 drill bit. 

The extra set of wires to be installed from "LE" (red wire) and "C" (black wire). Using wire nuts to join the wire back to the TS2 (leaving off photo in foreground), wire to S1 (middle), and wire to S2 (background).

Once the wire assemblies were ready, I proceeded to thread the bare wire ends through the switch opening like you would on a decoder. Once wrapped around, I soldered to create a strong connection. Until finished with the wiring i used blue painters tape to hold the wires in place. Permanently plastic holders will be installed. 

Using Microsoft Word I created a simple panel with where the buttons would be mounted along with instructions for operating. Once printed I cut around the border and laminated. Using the blue holes as a template made drilling on the fascia very easy. Use a small drill bit to mark the center of the drill hole, then remove the panel and use the proper size bit to make hole in fascia. 

Finished product installed on fascia. Not only does it provide instructions for the operator but also provides a very neat professional look for your layout. 

Lastly after all sensors, signals, interlocking panel were installed and tested it was time to close up the TS2 control box. A size latch keeps it securely closed but allows for easy access saving your head and neck. I ended up painted the boxes with Rustoleum Primer Gray. 

There we have it, another TS2 with two signals installed, linked to rest of signal system, and interlocking ability added. On Friday we will walk through the operation step by step of the interlocking to give you an idea how it operates and ways you can use this on your railroad


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