LIONEL TRAINS GANTRY SIGNAL BRIDGE No. 452

You may use one insulated track block, (made with either one or more track sections) to activate a relay. The relay, depending upon how it's wired, can change the signal from red to green or green to red.

The relay is wired so that its coil is energized by the wheels of a passing train, and its transfer contacts (SPDT) energize the lamps.  If you use DC for the relay coil circuit, you can make a circuit that does not chatter, flicker or drop out when dirty wheels go by.

The 452 is essentially "half" of a 450, or equivalent to a 153 and more recent versions. There are three contacts in the base: one common and one for each of the two lamps.

https://www.tandem-associates....l_trains_452_acc.htm

Thank you, Arthur for your reply.  I'll experiment with insulated track to see if I can solve the wiring sequence.

BTW  my power source is a ZW transformer.

Urbie

You can create DC easily from an available AC source, taken off one of the ZW outputs, or you can use a 12 volt junk-pile wall wart from various small appliances or gadgets.

Altronix model RB1224 is an easy-to-use example of a relay. They are cheap and can usually be found on Ebay for less than ten bucks. A diode bridge (a dollar) and a filter capacitor (a few dollars) will be all you need.

https://www.altronix.com/products/RB1224

Thanks, again, for the suggestions.

When Lionel introduced some of their popular accessories in the 1950's there were instructions that showed how to use insulated track sections in place of the 145C contractor, but not the 153C's.   So using the parts in your post were not referenced in any of Lionel's instruction sheets or operating manuals.  Probably because they were not available. 

When you use an insulated track section without a relay, you only get an "on-off" circuit operation, which is what the 145C provides. The relay provides the red/green choice, which is what the 153C gives you.

Should have asked is the Altronix model RB1224 relay manually operated or is it automatic when the metal wheels hit the insulated track sections?  TY

Here is how to wire it

https://www.azatrax.com/block-detector-3rail.html

Thanks, Steve, for weighing in on the conversation.  The wiring diagrams are very helpful.

Since ZW's produce up to 20V of power, the MRAPR -12V DPDT relay 8A appears to be the better of the 2 choices.  It is rated at 10-17 volts AC or DC coil voltage.  Do you agree with this assessment?

Urbie - Use the 10-17 volt version.   Set the ZW accessory power to something less than 17 VAC to drive the relay coil.   I run my accessories on 14 VAC.   If you use separate transformers to power the track and accessories using insulated rails remember to phase the transformers and connect the commons together.

Steve.  Thanks, again, for the value added pointers.  After reading the information on the MRAPR -12V DPDT relay 8A relay, it appears no other components are necessary to operate the No. 452 Signal Bridge...just this relay.

I use O'Gauge tubular track, and modifying sections to insulated "block" use, is fairly straightforward.  Arthur P. Bloom suggested in his post that a diode bridge, and a filter capacitor would also be needed.  However, Arthur had recommended using a Altronix model RB1224 relay which may require the use of these additional components in order to operate the 452. 

Is that also your assessment?

@Urbie posted:

Steve.  Thanks, again, for the value added pointers.  After reading the information on the MRAPR -12V DPDT relay 8A relay, it appears no other components are necessary to operate the No. 452 Signal Bridge...just this relay.

I use O'Gauge tubular track, and modifying sections to insulated "block" use, is fairly straightforward.  Arthur P. Bloom suggested in his post that a diode bridge, and a filter capacitor would also be needed.  However, Arthur had recommended using a Altronix model RB1224 relay which may require the use of these additional components in order to operate the 452.

Is that also your assessment?

The Azatrax relay board contains a diode bridge and transient  (flyback) suppression to guard against the voltage spike when the coil field collapses.  The capacitor would smooth the DC and suppress electrical noise which might minimize relay chatter caused by the wheels completing the circuit on the insulated track section.  The purpose of the diode bridge is to convert AC to DC in order to drive the DC relay coil.

Subscribing to the KISS principle (Keep It Simple Sailor) if I understand your explanation correctly all that is needed to install the No. 452 signal bridge is the MRAPR -12V DPDT relay 8A.  Connecting to appropriate insulated track sections, and the correct common and power terminals to the ZW is all that is needed.

I hope I have this correct.  Thanks again.

You could also use this IR sensor in the sustained activation mode.   https://www.azatrax.com/install-D2T-DS.pdf

Another great option...thank you.

Delighted to see this topic was recently initiated and discussed on the Forum, since this weekend I plan to install a new modern Lionel Double Signal Bridge (which is very similar to the single track Gantry Signal) using insulated track sections to activate it on my layout. I had the Postwar version of this accessory using the weight bearing activation devices on my layout, but lost the green light.

FYI, the Owners Manual for this modern accessory explains various ways to hook it up, including using 8 inch Female Pigtale Power Cables (#6-82038) and insulated track sections on a tubular track layout, and without the need for relays.

I will share my progress with this project in later posts. Arnold

As a follow up to my post immediately above, good news is I installed the modern Lionel double track signal bridge using Pigtail Power Cables and tubular track with insulated rail to serve as the trigger making the light change from green to red as the train passes by.

It works great. IMO, the modern accessory is superior to the Postwar one using the weight bearing trigger devices.

The modern accessory came with a manual that clearly explained how to attach the wires to the accessory, transformer and insulated rail, and the wiring was better organized.

I guess the insulated rail trigger can also be used for the Postwar accessory.

Bad news is my layout is currently a mess because I had to dig up and detach several tracks and move some scenery to install the insulated rail tracks.

Once I spruce up the layout a bit, I will post some photos and videos, probably tomorrow or Sunday. Arnold

Victory!

Incidentally, I still have the Lionel Postwar single track gantry signal on my layout.

It uses the old fashioned weight bearing trigger and it works fine.

The single track gantry signal is more accessible, so I can periodically adjust it.

Such is not the case with the Lionel Double Track Bridge signal on my layout, which requires some model railroad yoga on my part to reach it. That is an important reason why the insulated rail trigger, which requires no periodic adjustment, is so much better for my Double Track Bridge Signal. Arnold