TAKING SLACK

[BigJim]

efftenxrfe

There needs to be a realization that combined train air brakes and dynamic brakes are what is needed for downgrades.

That is exactly right.  Having a good air/DB balance set up going downhill can quickly go sour if a unit loses its DB.

As for complete DB failure, now a days, the company goes ape+#@* if an engineer tries to learn how to power (stretch) brake. It was an art I was fortunate to learn before all of this fourth grade hall monitor  techno-blabby wizardry was installed on the units. An engineer needs to know how to do this just in case something fails so that he can handle the train safely. 

As for retainers, I know that eastbound coal trains out of Bluefield, W.Va. used retainers on about the head 20-30 cars as it is a long way down to the foot of the mountain. I don't know if they still do. My grades weren't that long and the profile such that we didn't have to use retainers. I don't think their use would have been discontinued. I'm sure there are plenty of grades out west and some here in the east that require the use of retainers.

[BaltACD]

BigJim

efftenxrfe

There needs to be a realization that combined train air brakes and dynamic brakes are what is needed for downgrades.

That is exactly right.  Having a good air/DB balance set up going downhill can quickly go sour if a unit loses its DB.

As for complete DB failure, now a days, the company goes ape+#@* if an engineer tries to learn how to power (stretch) brake. It was an art I was fortunate to learn before all of this fourth grade hall monitor  techno-blabby wizardry was installed on the units. An engineer needs to know how to do this just in case use of retainers.

I was reading through my company's Engineers Bulletins - I saw one bulletin wherein the experienced engineers were being instructed to train the trainee engineers on the art of 'stretch brakeing'.  While stretch braking is not the approved braking method, there are locations and situations where this method is called for.  The company desires to have their engineers know the proper way to do stretch braking, even though it is not the approved general method of braking.  The experienced engineers would not be 'down graded' for stretch braking while they were training someone.

[Deggesty]

Balt, from what you say, somebody in management is aware of reality. Perhaps, someone who has had much experience in running an engine?

[BaltACD]

Deggesty

Balt, from what you say, somebody in management is aware of reality. Perhaps, someone who has had much experience in running an engine?

The company's Chief Transportation Officer still maintains her Engineer's Certificate and does qualification runs as required by law to keep it current.

[jeffhergert]

We are allowed to stretch brake, but not to power brake.  The difference?  What throttle notch you're operating in.  They consider operating in notch 6 and below to be stretch braking, above that and you're considered to be power braking.  For awhile, they had changed the meaning of stretch braking to only being in notch one or two, anything higher and you were power braking.  Someone with actual experience running trains must have been able to get them to change it back.   

Even though stretch braking is allowed, it's still preferred to be used when other more fuel efficient methods aren't practical.  They do stress dynamics, almost to the point where young engineers are afraid to use air.  One time I had a student who needed to get slowed down right away because the approaching train on the adjacent track went into emergency about a mile away from us.  Instead of immediately setting air, he was going to notch down on the throttle and go into dynamics.  I told him to use air and get the speed down, you don't know if the train who lost his air did so because a hose came apart or he's got cars derailed across the tracks.  

Jeff     

[BigJim]

BaltACD

I saw one bulletin wherein the experienced engineers were being instructed to train the trainee engineers on the art of 'stretch brakeing'. 

That is good to hear.
I can remember when one prominent Regional RFE told us that "There will be no more air brake artists out here"! What a maroon!!! 

[Anonymous]

BaltACD

GM1361

What is taking slack in the following sentence?

CAUTION: Taking slack is not a recommended method for
starting a heavy train on a heavy grade. Short brake release
times will release the brakes on the entire train, and the rearportion will begin rolling backward while the head portion is
starting forward, easily causing a train separation.

Couplings between cars have some 'slack' in them - potentially on the order of 1/2 inch to a inch per coupleing + the movement of the draft gear on each end of the car.  As train lengths increase, the amout of 'free moving' slack in the train also increases.  Improperly controlled slack action is the primary cause of shattered coupler knuckles and pulled out draft gear.

The action described in the 'CAUTION' is a situation where the entire train is stopped on a ascending grade.  The engineer has 'bunched' the slack in the train, so that each coupling has the maximum slack distance to move before starting to pull on the car behind it.  In the procedure being cautioned, the air brakes are applied on the entire train.  As the engineer begins to start the train, adding power to the locomotive consist, he is also releasing the air brakes - pulling the slack out and starting each car individually from front to rear.  The caution refers to the fact that the brakes will release on the rear of the train before the starting secquence of pulling out the slack has gotten to the rear of the train.  Gravity will have the entire portion of the rear of the train pull against the starting head end of the train as a 'solid unit' with a much higher draft force than the engineer intends with his starting sequence.  The high draft force is easily capable of shattering a coupler knuckle or finding the weakest draft gear, thus stopping the train and necessitating additional actions being taken. 

Very informative response!  What is the total distance a freight car will move before it begins to pull the car behind it?  Someone told me years ago that it was in the neighborhood of six inches, i.e. three inches for each car.  I have no idea whether he knew what he was talking about.

[BaltACD]

Six inches per normal coupling car sounds reasonable - 1/2 inch or so in the coupler, 2 1/2 inches in the draft gear on each end of the car, maybe less....then you have cushion under frame cars that can have a couple of feet of travel.

[efftenxrfe]

Slack, a wondrous thing in concept, theory and application.

Let's work an idea that braking power/effort of a/group of cars, while varying,, affects slack, and thus, different speeds within a train. That speed within the train blows into importance when the difference is like holding a piece of string between your fingers and pulling on it...or instilling a loop of slack and then pulling them apart....right? 

Said that, and some may wonder where's this is goin?'

This is about "little  train's,' on big 'roads: 'tween four to eight thousand feet trains powered on only the head end.

On very gently rolling right of way with a high throttle position effectively, slack thus stretched, widen on the throttle, more slack is pulled out. Time a minimum reduction, in your mind, like an NFL Quarterback, the additional stretch...but follow with an automatic application arriving at the end of the train when reduction of the throttle reduces speed fastest, low or no throttle and  surely, kick off the (auto) brakes coming into the restrtiction

Slack  action happened. while releasing through the restriction of speed, while with little. slack had the time to readjust to what was the tolerable state that got the train this far.

Now the slack is there for the massaging.

It's your railroad: drift, bunch or strech... ya' have to do some thin'