"snic2880"
Thanks Sand Box John, however, I am not clear what "cab signal" is. It would seem that as the operator increases the throttle to start away from a stop there is no "radio frequency" signal, but rather a direct connection (electrically) from the throttle to the motors in the cars. Am I simlyfing too much, is there more involved?
Don’t confuse the connection of the operators controller handle to the propulsion system with 'Cab signals' or 'Speed Commands'.
The cab signals or speed commands tell the train how fast it may go.
There are 3 speed displays on the operators console. The left display shows Limited speed, the middle display shows Regulated speed, the right display shows actual speed of the train. The Limited and Regulated displays are what I am talking about when I use the term cab signals or speed commands.
If one or both of the Limited and Regulated displays (usually both) goes to zero, that is loss of cab signals.
When those displays go to zero in automatic mode the train will automatically apply the brakes until the train come to a complete stop or until the display start showing a speeds again . In manual mode an alarm will sound in the cab indicating to the operator to move the control handle to one of the brake positions. The operator has a limited period of time between the sounding of the alarm and moving the control handle to one of the brake positions before the trains fail safe system cuts in and fully stop the train.
The limited and regulated cab signal displays get their information from wayside by way of audio frequencies (8 channels ranging from 2,100 to 3,900 KH) transmitted through the running rail track circuits. Channels 1, 3, 5 and 7 are assigned to track 1, channels 2, 4, 6 and 8 are assigned to track 2.
There is an antenna array under the cab that receives the signal transmitted through the running rails.
Additionally there is 2 other channels (channels 9 and 10 in the 9,800 HZ range) used for train to wayside communication. Information transmitted to wayside from trains are train number, train length and destination.
Last edited by Sand Box John on Tue Sep 09, 2008 11:35 pm, edited 1 time in total.
John in the sand box of Maryland's eastern shore.