SSPRR Run Room

Playing with Toy Trains

Toy Train Layout Wiring - Engine Safety Relays P.2of2

Basic Intermediate Advanced Wire Management Bus Wiring 120V Train Room
Glossary Wire Sizes Switches Load Calculations Soldering Troubleshooting

see Lift Bridge with Lift Assist Serving the Two Main Lines on P. 1

 see Lift Bridge with Lift Assist Serving the Outside Main Line on P. 1

Lionel 022 Switch Wired to Control Track Power
with Relay for Engine Protection

When an access bridge can't switch the track power, the bridge can switch a relay.

Pre 2004 Layout Wire Color Coding

Red #14 for Elevated Table Track and Orange #14 for Bridge ascending/descending Variable Voltage,
White for Transformer Common, Purple for Switched Common, Red #16 is 16V Switch Power

The 317 Bridge Track and the Loop Track are on Different Voltage Sources
The 022 approach track at the bottom of the diagram must be dead when the bridge is open
and the switch is set to go left into the hole.  Power must stay on the loop when bridge is open
and switch is set to continue right around the loop.  A relay does the trick.

Lionel 317 Trestle Bridge as Lift Bridge Lionel 022 Track Diagram

Bridge Acts as a Switch to Control Track Power 

The magnetic cabinet catch holds the steel
bridge in up postition.  Flexible wires power
the bridge track
Hinged End with Magnet Catch 
The open end of the metal bridge closes the
switch contacts.
Bridge Opening End 
Bridge Up  The switch contact points close the
switch when bridge is down.
Contact Points for Closed Bridge

022 Switch Controls Track Power 
022 Switch Wired for Track Contro.

The distance between the right insulating pins and the 022 switch must be long enough
so the train will not coast through the 022 switch.

 When the turnout is aligned toward the bridge the approach track commons
are disconnected at the relay. When the bridge is down the commons are
connected through bridge contacts and the train can proceed.


Wiring Diagram for Track and Relay

Wiring Notes
Use a Latching Relay. Relay used here is a Tyco Electronics/P&B K10P-11D15-12
DPDT 30 VDC / 120 VAC, 10 A at 277 VAC with a
General Purpose/Industrial Relay DPDT SOCKET MT 12VDC.

Diode Hint
Use a digital multimeter to test the polarity of a diode in the event the polarity markings
are absent or missing. Simply turn the meter unit on and turn the dial to measure "Ohms."
Hold the black (negative) test probe to one metal leg of the diode and the red (positive)
test probe to the other metal leg. If you see no reading, or just a "1" displaying on the
meter, reverse the probes. When you get an actual reading in ohms on the display,
note the side the negative (black) probe is on. That is the cathode (negative) side of
the diode.

This circuit worked flawlessly for several years.

Relay and Terminal Strip Wiring 


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