Gregg posted:That's a good question, "why did the previous crew put the train into emergency rather than a full brake application?
I'm assuming the dynamic brakes could not hold the train and as soon as the air was recovered the brakes released, with not enough time to fully charge the train line and the train moved out on it's own.
Reportedly, the new out-bound crew had not yet attempted to "recover the air brakes", as the train moved out on its own.
However a train left in emergency should not Bleed off in a few hours. There must be something else going on..
Maybe the outside temperature being below zero degrees F may have had something to do with it.
Question ....what happens to DPU units inside a tunnel?
Generally, nothing as there are "repeaters" for the radio signals inside the tunnels.
Do they stop loading,
No.
What happens to the dynamic brake on these units with loss of radio communications.
As stated above, there is normally no loss of radio communications for the DPU. However, if there is a "loss of radio signal", the DPUs are usually programed to operate at their last received radio communication, or until brake pipe pressure is reduced, then they drop to idle (when in DP, they may continue to provide braking effort).
