Railroad Forums 

  • Flashing lights on side of cars while braking?

  • Discussion related to DC area passenger rail services from Northern Virginia to Baltimore, MD. Includes Light Rail and Baltimore Subway.
Discussion related to DC area passenger rail services from Northern Virginia to Baltimore, MD. Includes Light Rail and Baltimore Subway.

Moderators: mtuandrew, therock, Robert Paniagua

 #1333891  by MCL1981
 
What are the amber lights on the side of some cars that flash when the train in braking? The seem to only flash when the train is coming to a stop, which leads me to believe they're related to the air brakes. But I can't figure out if that's coincidence, and why?? They are only on some cars, I don't know what series.
 #1334068  by Sand Box John
 
You pretty much answered you own question. On the 1k cars the light are on the rear end bulkheads one light indicates dynamic / regenerative braking is being applied the other friction braking is being applied.
 #1334249  by tommyboy6181
 
MCL1981 wrote:What are the amber lights on the side of some cars that flash when the train in braking? The seem to only flash when the train is coming to a stop, which leads me to believe they're related to the air brakes. But I can't figure out if that's coincidence, and why?? They are only on some cars, I don't know what series.
They're on the 1000, 2000, 3000 and installed when the cars were rebuilt. The 6000 series had them installed from the beginning when the cars were built between 2005-2008.
 #1335031  by Sand Box John
 
"MCL1981"
OK. Which leads me the other half of my question.... why????


So that a person on the ground can tell when the brakes are being applied. As in the confines of one of the shops or yards or along the mainline.
 #1339393  by jim121049
 
The flashing amber indicator on the right side of some rail cars is known as the “Brakes Not Fully Applied” fault indicator. It is only found on 1K,2K-3K and 6K cars. There is an amber indicator light on the side of 5K cars but it does not flash nor is it a brake fault indicator. On 5K cars the ambler indicator on the side is illuminated to indicate that ATP (Automatic Train Protection) has been cut out. There is no amber indicator on the side of 4K cars.

The “Brakes Not Fully Applied” indicator is intended to help the operator troubleshoot friction brake problems. If an operator is experiencing friction brake problems, he or she can look out the cab window at the indicators on the side of the cars and and quickly determine which car in the consist is the source of the problem.

The reason that the indicator is seen briefly illuminated when the train is stopping at the station is due to a simple assumption made about friction braking. The assumption (not always true) is that if the friction braking system on a car is working correctly, the friction brakes on that car will be either “released” or “applied” (for this discussion “applied” specifically means friction braking at a level at least 85% of Full Service Braking). The “Brakes Not Fully Applied” indicator flashes to indicate a fault when the friction brakes on the car are neither “released” nor “applied”.

When a train is stopping at a station and the speed is still above about 15 MPH the car’s propulsion system will be providing all the braking effort needed using dynamic/regenerative braking. Since the propulsion is providing all the braking effort needed, the friction brakes will be released, therefore the “Brakes Not Fully Applied” indicator will be off.

When the train speed gets below about 15 MPH, however, the dynamic/regenerative braking provided by the propulsion system starts to ramp down, decreasing as the speed decreases. (This is called “brake fade” but it’s not the kind of brake fading you might experience in a car with drum brakes when the brakes get hot going down a mountain road. This “brake fade” is done purposely to make a smooth transition between dynamic/regenerative braking and friction braking.) Since the propulsion system is now no longer providing 100% of the braking effort required, friction braking starts to ramp up, increasing as the speed decreases, to make up for the decreasing dynamic braking. The friction braking is said to be “blending” with dynamic/regenerative braking so that the two together (friction and dynamic/regenerative braking) combine to provide 100% of the required braking effort. During this “blending”, the friction brakes are no longer fully released as they were when the speed was above 15 MPH, but are in the process of ramping on. However, they have not yet ramped up to 85% of Full Service Braking. Therefore, the “Brakes Not Fully Applied” indicator flashes.

Once the train speed decreases below about 3 MPH, the dynamic/regenerative brakes will have faded to fully off and the friction brakes will have ramped up to fully applied (if they’re working correctly) and the amber indicator will now extinguish.

I hope this rather long winded explanation is clear.
 #1340013  by MCL1981
 
That explains perfectly everything else I was wondering. Thanks.

Actually, one more thing. For the cars that have the flashing brake indicators on the end bulkheads (4s and 5s?), doesn't that defeat their purpose? You can't see them.