No DBI for BN Units

[dej716]

[%-)] In reading this through, I'm wondering if some are confusing dynamic braking and automatic braking? As I understand it, dynamics have nothing to do with automatic brakes.
I''ve heard that on some units the independent (engine) brakes may apply during dynamic braking, hence the DBI. One engineer I've worked with always bails off when going into dynamic due to either the lack of or possible failure of a DBI on some units.
However, whenever the automatic (train) brakes are applied, the engine brakes also apply, hence the need to bail the independent. On the NS, it is required EXCEPT when there are more locomotives than cars (NS-1, L-243).

[2c]

[Anonymous]

One problem with DBI that I am familiar with, non-extender range DB, type 24 brake, is that when having a heavy reduction applied, say 15 lbs, then releasing the DB, the independent comes on and can cause slack to run in with a bang. Very disturbing to passengers on a tourist train. So I hold the bail down while killiing the DB, then immediately apply a little independent to keep the locomotive slack from running out.

[Anonymous]

If the D magnet valve becomes defective or if the exhaust port becomes blocked, Brake Cylinder pressure can remain even though DB is selected.

I have had BC pressure go from 0-350kpa instantly when coming out of DB. I believe the explanation was that air became trapped between the D magnet valve and the blocked exhaust port which, when I came out of DB, re-entered the Brake Cylinders.
All very good reason's to bail off when making an Automatic Application whether using DB or not.

Danny
Australia

[bnsfhogr]

You'd probably want to ask the engineering department that question.
A likely enough answer is that in the event of dynamic brake failure, the company would want the independent fully functional without possible impedance.
By rule, on the BNSF...

103.5

2. When operating a locomotive consis and it is desired to prevent the locomotive brakes from applying during an automatic brake application, the independent brake valve handle mus be depressed in RELEASE position a minimum of two seconds per locomotive prior to the automatic brake application and held depressed until exhaust ceases.

3.The independent brake must not be applied while power or dynamic
brake is being used,except when starting or stopping while in the dynamic brake mode and speed is below the effective range of the dynamic brakes being used. Light independent brake may be used to control wheel slips at speeds below 10 MPH only.

[wabash1]

its been so long that i dont remeber if some of the old up engines might be the same way. i cant remeber it is just force of habit i just bail anyways so i never know anymore if i do or dont have one of those engines.

[BigJim]

The sliding of wheels is the main purpose of my question. What would be the purpose to have engines applying the independent while in D/B? Is BN too cheap to pay for the DBI? I have to caution my trainees that when ever we have a BN unit the independent must be bailed off with each automatic application or they may start sliding the wheels.

[Randy Stahl]

I've been looking through my old BN prints and indeed there are some engines without extended range dynamics that do not have a DBI. Some thing to be aware of if you have a BN engine in trail. even though your lead engine is not getting BC pressure your trailing ,non DBI engine will be. Good chance of sliding wheels on your trailing engines.Probably a good idea to actuate like Wabash said unless you know for sure ALL of the engines in your consist have the DBI.
Randy

[wabash1]

Randy it has been sometime since i have had a bn engine that did this . what he is refering to is when your in dynamic comming to a stop and you get first service the engine brakes also apply . I cant remeber what the valve name is but on some of the old sd 40 units the engine would apply while in dynamic and this is why i have a habit of anytime i get air i automaticly bail.

[arbfbe]

They have installed a locomotive engineer and actuating capabilities on the independent brake valve to handle this function. Older engineers knew there was more than one purpose for a switch key.

Alan

[Randy Stahl]

QUOTE: Originally posted by BigJim

Why doesn't BNSF put a Dynamic Brake Interlock on it's units to keep the independent brake from applying when the automatic is applied in D/B?

I assume that the engines still have the IPS that drops the dynamics out when there is 15 psi brake cyl pressure. I wonder , what engines are you seeing this on ? The older BN stuff that I'm used to had the DB interlock.
Randy

[BigJim]

Why doesn't BNSF put a Dynamic Brake Interlock on it's units to keep the independent brake from applying when the automatic is applied in D/B?