A non electrical track brake is a row of brush bristles between the rails to rub the flages. Folks use these in modeling hump yards.
I guess ramping speed is high enough eh? 
Some folks do electric versions that pivot on one end and adjust closed by a rack and worm drive near the other end. Stepper motors and led/opto auto speed control too 
Just avoid the temptation to wire one of the uncouplers to a normal switch. They will get hot enough to melt if they dont get cooling time of a temporary on switch/button. 
I've seen them up close on layouts, but never had or used one, but thought they were very cool anyhow.
