Canadian Railroads > GMD1 "Snow Brake" Question

Oregon Pacific operates former CN GMD1 1413 which is equipped with A "Snow Brake" which when the switch is turned to on appears fully functional applying about 2 psi brake cylinder pressure.

What the heck is this used for..helping to control wheel slip/creep or what? Your input is solicited!

Dick Samuels
Oregon Pacific Railroad

From having what I would say is the same problem in snow service between Emigrant Gap and Truckee on the former SP.  That switch automatically keeps 2 psi. on the brakes which will keep the ice out from between the brake shoes and the wheels, which means the brakes will work when needed!
G

I agree with what ExSPCondr says and will add the following. I would suggest that the 2 pounds of air also is just enough PSI to keep the brake shoes against the wheel to provide sufficient friction to prevent snow and ice build up so that when ones does need to slow down there is no lag time needed to first melt snow and ice build up common during winter operations.

Posted from iPhone

The first CP switchers to come equipped with composition brakes shoes rather than cast iron were the SW1200's.  When they first went into service in yards and on local freights, the engineers cursed them because the brake shoes didn't heat up and hence could become covered in ice.

Cast iron shoes and composition shoes have different mounting assemblies, meaning trucks designed to use composition shoes couldn't use cast iron.

​Once crews understood the different friction offered by composition shoes rather than cast iron, they learned how to properly "condition" composition shoes in winter weather.

​CP didn't have an "ice switch" but in all powder snow conditions, many ran around with a 5 psi application on the independent all the time.

 



Edited 1 time(s). Last edit at 11/29/16 09:45 by eminence_grise.

agreed, the new Siemens ACS64s and SC44c (Chargers) both have snow brake features, which keep the brake pads and discs from icing up.

BC Rail  RDC's had at some time, a snow brake feature. Not sure how effective it was.  Doug

eminence_grise Wrote:
-------------------------------------------------------
> The first CP switchers to come equipped with
> composition brakes shoes rather than cast iron
> were the SW1200's.  When they first went into
> service in yards and on local freights, the
> engineers cursed them because the brake
> shoes didn't heat up and hence could become
> covered in ice.

I knew a BN engineer who would have been fired for that situation had he not retired on the spot in lieu.


> ​Once crews understood the different friction
> offered by composition shoes rather than cast
> iron, they learned how to properly "condition"
> composition shoes in winter weather.

TAW



Edited 1 time(s). Last edit at 11/29/16 13:24 by TAW.

Had these on the MR20's as well. The snow brake, when on, would apply a bit of pressure on the wheels as the composite shoes would get built up with ice pretty quick in our wonderful Canadian winters. That would keep just a little bit of warmth on the shoes and prevent ice build up.  I always found it was more effective to just put a touch of engine brake on every once in a while. I always found the snow brake didn't always release if a brake application was made. It seemed the pressure would go up with an engine brake application, and when the brake was released, the snow brake had crept up sometimes as much as 10lbs!  The MR20's and HR412's had only one shoe per wheel (which didn't allow it to stop, or hold worth a crap in winter!), so they would build up with ice and snow very easily.

Most of the Union Pacific run through power I have that is from GE (AC45, Evo's etc) have this feature, for the reason listed above-keeping the shoe lightly against the wheel keeps ice from building up making the comp shoes worthless. Occasionally former Conrail SD60i's had this feature.  Most engineers think there is something wrong with the engine, and report it to the mechanical help desk.  Nobody teaches engineers about that stuff anymore, I guess. just push buttons and let the trip optimizer run the train for you.
As a young engineer turned loose on my own, I had a scary moment once when I was on a local during a blizzard. I went to stop on light power at an industrial spur to clear the mainline and kept...right...on...going...lucky it was a mainline switch I missed, so the consequence was looking like a dummy in front of the conductor and having to back up...coul've been a whole lot worse if that was, say,  the other way around and I was on the spur and couldn't stop before entering the mainline.
They say experience is the best teacher,  I tend to agree.
Enjoy your GMD's, super awesome winter abilities, with CN's compliments!  You could turn it on if you are want to do some real razzle-dazzle lead job drilling cars by kicking down the lead--keeping the brakes heated up like that can give you shorter stopping distances, obviously.

 

Firstly, thank you for taking such good care of one of our GMD-1s. CN added a "snow brake" to a few units the rebuilt GP9s, GMD-1s, as well as the M420/HR412(W)s. Keeping the shoes warm really helps the stopping distance, in cold and snowy conditions. CP could ahem add it to the GP38-2s, terrible units to take off the shop track in the Winter.