Thanks Carlo,
1) In UK this is only used in diesel electric locos. I believe other countries in Europe may have slow speed control in electric locos, but it may operate differently.
2) My understanding is that it only uses electrical power to the traction motors, but I will try to confirm if that is correct. [ @Coolhand101 may know ]
Most locos so fitted did not have dynamic brakes, but I will try to find out if the system could apply the air brake if needed.
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3) I'm not sure I understood the "balancing speed" way of working. If throttle is closed and slow speed control is disengaged, how can the train keep a speed? Is position OFF present also in case there is a "balancing speed" position?
Links to some instructions are given below. From these, this is what I assume needs to happen:
(1) Driver moves throttle to OFF and uses brakes to stop train or reduce speed to very low.
(2) With throttle at OFF driver moves reverser from "Forward" to "Engine Only" (=neutral in ORTS) and selects slow speed with slow speed controller
(3) Driver moves throttle from OFF to ON
====== Train operates at slow speeed with engine at idle until ========
(4) Driver moves slow speed control to OFF - train speed then increases to what it would be with the throttle at ON (engine at idle) if there were no slow speed control (6-7mph)
(5) Driver then moves throttle from ON to OFF, then moves reverser from "Engine Only" (neutral) to "Forward" and then moves throttle from OFF to ON.
I will try to confirm if this is correct. There is some description of operation in these:
http://www.locodocs....general1987.htm
http://www.locodocs....nstructions.htm