How do the different cab signaling systems get suppressed? For instance, I understood the procedure to be any cab signal reduction requires placing the brake handle in suppression (which is a large pipe reduction, 20lbs?) until the speed is below the newly required speed. Is this accurate? If so, how is that proper train handling when on a non-cab-signaled route, the engineer might use the dynamics instead of the air?
If the track is only equipped with automatic cab signals (ACS) without a form of speed control system being involved, it is not necessary to go to suppression. The operator merely acknowledges the signal restriction and brakes accordingly to comply with the speed required for compliance. If the signal changes to a less favorable than clear, and the operator fails to acknowledge the signal in the time allowed, then a suppression application is the only way to recover from a penalty situation, and thus requiring a full stop. Speed control changes all of that, in that if speed does not reduce sufficiently, a penalty will occur, which can only be taken care of with a suppression application and a full stop.
And, yes, a full stop penalty is not conducive to good train handling on a long, heavy freight train.