Functions; Functions: More Information - GMC Rapido F9B Operating Manual

Note that if you are listening to your F7B/F9B idling nicely and then you select
another engine, your locomotive still thinks F8 is pressed so it will keep idling along.
However, if someone else selects your locomotive's number and F8 isn't pressed on
their controller, the F7B/F9B will promptly shut down. They will need to press F8
again.

FUNCTIONS

PLEASE NOTE: These functions are designed to align with our FP7 and FP9A
locomotives. Missing functions are those found on the FP7/FP9A but not on their
B-unit counterpart, with a few exceptions.
F1 Bell
F2 Horn
F3 Full Throttle
F4 Dynamic Brake
F8 Startup/Mute/Shutdown
F9 Front Headlight
F10 Rear Headlight

FUNCTIONS: MORE INFORMATION

F1 Bell
These units never had a bell. We know that. Or if they did, it was well and truly
hidden and only used for switching around the yard using the internal hostler controls.
But its here in case you have an A-unit without sound, should you choose to use it.
F2 Horns
These units never had a horn. Well, they did, but not the type you'd expect on the
roof of a usual locomotive. They often had a single-blatter horn on one end - almost
like a truck horn - and was used exclusively for marshaling in yards when run solo
using the previously mentioned hostler controls. Again, in the event you have a silent
A unit and you'd like sound, we've included recordings of standard horns, but we've
additionally included a single-blatter recording as well. See the next section about
changing that.
F3 Full Throttle
ESU's "Full Throttle" feature allows you to play the prime mover of your F7B/F9B like
a musical instrument. When you press F3, you turn on "drive hold." This keeps the
speed of the engine constant at whatever speed step your throttle happens to be on.
Then as you increase the throttle, you hear the prime mover revving up. This sounds
awesome, whether you're taking off from a commuter station stop at warp speed, or
trying to get up that long, slow freight over the grade. The prototype is normally very
overpowered for the short trains it is hauling. The high power is used for high speed
rather than high tonnage.
F11 Brake
F12 Doppler Horn – Slow
F13 Rail Squeal
F14 Steam Generator
F15 Switching Mode
F16 Doppler Horn – Fast
F20 Brake Set/Release
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