Input from folks who understand this is useful to my question. Thank you.
At this point, I have to note that:
- in my case the "emergency brakes" are the same brakes used on the the car all the time. The disk brakes with an actuator. Not a special "parking only" brake.
- assuming I can figure out the switch, the brakes would be applied aggressively AND with benefit of the anti-lock feature ! (per a Chrysler publication that I found).
- Frankly my goal is a breakaway system that a) will likely never be used anyway, and b) satisfies me and the break-away regulations that it will "work". I am careful about maintaining and monitoring my tow bar and emergency cables, so meeting the regulation requirement is my primary goal.
- This would apply only the rear brakes. But a car careening away after towbar AND safety cable failures is a messy prospect anyway, isn't it? :E
