Anyone have an idea what size reed switch, volts/amps, I could use to activate the brakeman car? I had a couple reed switches laying around but after activating the brakeman a few times the switches would fail. 18volts and who knows how many amps the relay is pulling was to much for the tiny reed switches I had.
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Reed switches typically carry only small amperage. A solution would be to have the reed switch work a relay coil,then let the relay contacts switch the accessory or accessories in tandem. Relays with 10 amp contact ratings are adequate for most switching jobs in model railroading. The relay coil typically uses from 1/4 to 1 watt depending on type and design,an easy load for the reed switch.
Dale H
However, I'd protect the reed switch contacts with some transient protection so they don't weld themselves shut.
Don't ask me why I know this. 
What does this car do? Activate a solenoid to move something (unfamiliar with this piece)? Relay probably best way if you can find one small enough to fit and rewire the car. Might have to include a diode for a DC relay or use an AC if available in small footpriint.
My 2 cents.
I agree with the relay, my point was the kick-back from the relay coil will also stick the reed switch. No way you're powering the solenoid in the brakeman car with a reed switch! If you use a DC relay, you'll probably need a capacitor in addition to the diode, otherwise the relay may chatter.
I have a 12v relay which only uses 1/4 watt. I doubt this would harm the reed switch. My impression was it was a parked car and the relay was mounted on the layout powering the car through an accessory track. The relay has a built in diode across the coil so there is no kickback.
Dale H
It's not the power, but rather the inductive kickback when it opens that welds the contacts. If it has a diode, that's good. 
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