I'm restoring a ZW model R. In testing the two whistle control switches with both a whistle ltender and diesel with a horn both whistle switches on both sides of the ZW when moved about 2/3 of their full travel produce a consistent whistle or horn sound. But if the switch is pressed all the way to the end of travel the whistle or horn drops out and sometimes the engine e-unit cycles. I can get pretty good at getting the whistle or horn to work so long as I don't push the switch too far. Is this normal or should they sound and hold if I push the switches quickly all the way?
Completely normal.
If you study the schematics and the Lionel whistle operation theory, you will see that there must be a load on the circuit beyond that of just a standing/idle piece of equipment to draw enough current through the rectifier to reach the "hold" threshold voltage of the DC component imposed on the AC.
Rob
Your contacts are dirty, clean with 2-26 electrical cleaner. And most likely after more then 50 yrs the whistle diodes are breaking down and need to be replaced. You can use a 6-10A stud rectifier with a 50PIV volt rating as a replacement. Been fixing whistles this way for over 10 yrs now.
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