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Steam & Excursion > How you can see if the car or engine had straight or auto brakes


Date: 03/21/20 20:02
How you can see if the car or engine had straight or auto brakes
Author: PlyWoody

If your photo of the car or engine shows the end of the equipment, the straight air line system was to the left of the coupler and the automatic air line is to the right of the coupler.  Facing the end of the car, your left arm represent the left side of the coupler and same for right.  If the brake wheel is on that front end of car, than that represents the left side of that car and wheels are counted from that end.  L1, R1, L2, R2; L3, R3' L4, R4. 

But their is a major variation on the front of steam locomotives as their first air systems were straight air line system so they were out in front, ahead of the engineer cab, on the left side of the coupler, and the angle cock was there where the trainman was in sight of the engineer when he needed to turn the angle cock.  When the automatic air system came into use with all air hoses to the right of the coupler, all the engineer objected having that air valve moved out of sight.  So they just used that same air line at the front of locomotives for the automatic air brakes as the air hose could be closely coupled to the first car and both angle cocks were at the working location in front of the engineer.  That system worked well into the diesel era and only in recent years since radios are the new locomotives being built with all hoses to the right of the coupler.  The tender fit the standard as the angle cock was also on the engineer side of the train.



Date: 03/21/20 20:10
Re: How you can see if the car or engine had straight or auto bra
Author: LarryDoyle

And, there's the DM&IR / CN way.

-LD



Date: 03/21/20 20:22
Re: How you can see if the car or engine had straight or auto bra
Author: nycman

Woule one of you be so kind as to explain "automatic air brakes" to those of us who do not know?



Date: 03/22/20 06:00
Re: How you can see if the car or engine had straight or auto bra
Author: wcamp1472

It was an advertising 'device'...

The first compressed-air brakes used the high air pressure
( from a compressor & tank on  the loco).  
When you wanted to apply the brakes, you pumped, stored,
 compressed air into the train,  the pistons in the brake cylinders
of each car moved and applied the brake shoes to the wheels.
( That means is called: 'straight air' systems)

Problem:  If the train separated, how do you get air to the separated cars,
                to apply the brakes?
             
                With the pipe open ( on the cars connected to the engine),
                how do you build-up air pressure in the cylinders to
                apply the brakes.....?

Westinghouse designed a system where each car carried its own air supply
and control valve.  If ANYTHING lowers the brake pipe air pressure below the
pressure in the air storage tank, each car's control-valve sends ( stored)
compressed air to the brake cylinder and applies the brakes AUTOMATICALLY... 

If a train separates, both sections are braked to a STOP..
If you slowly let some air out of the pipe, you begin to slow down,
If you restore BP pressure,  the brakes release, and you recharge
each car's storage tank.

As a complete 'system', cars and loco: the storage tank(s) on the loco
is called the Main Reservoir.  
The storage tanks on the cars are called the Auxiliary Resevoirs...

Several revisions, over the years, improved and changed the loco control
devices, but even today's loco systems will apply the brakes to the oldest
existing 'automatic' brakes , that may be found 
in museums and collectors..  
The oldest cars I've seen,  use the old K-2 control valve..

Now, those of you that want to know more....grab Westinghouse or NYAB  
books and read-up on their explanations.  
Prepare to be confused.

I learned the 6 & 8 brakes from ICS books, charts and cardboard
'models' ( of cutouts of the operating valves and levers)..

One thing I learned early-on, is that even the most highly knowledgeable
air brakes 'students' avoid the expression 'expert'.  
The systems are so tricky and confusing, that it's impossible to know all
the possible combinations of conditions that govern the systems.  
I've known many of the best brains, and they always stayed
curious, and wanted to be "thrown air brake problems" that seemed unsolvable.

But everyone of them has been stumped by problems in the past...
they cringe at being called 'air brake expert'.... tomorrow they may be 
facing an anachronistic challenge that is truly puzzling.  Airbake techs
often consult each other in these cases.  
It is a small, tight fraternity of life-long friends.

We are always at some place on the 'air brakes learning curve',
and we are eager to share with folks just beginning to journey
into the mysteries of Westinghouse's wonderful braking 'break-through'... 

W.

needs proofing, yet...


 



Edited 8 time(s). Last edit at 03/22/20 07:54 by wcamp1472.



Date: 03/22/20 09:33
Re: How you can see if the car or engine had straight or auto bra
Author: wcamp1472

Back to,the original question:
" How can you see if the car or engine had straight or auto brakes?"

On locos  99.9% of engines built after 1900, all were equipped with BOTH
'braking' sets of equipment .
Even today, locomotives operate with both systems: "straight air" & "automatic air"...

​The brakes on locos are used separately and independent of the train brake.
In fact, we call the controls for the engine brakes:  "The Independent brake".

It is the smaller brake handle in the cab --- it is used for the application and release 
of the loco brakes, including all engines 'slaved' to the lead unit through the 
multiple-unit control schemes:  electric ( including radio control) and air brakes'
connecting pipes and hoses.

Because locos are typically very heavy,  it  is advantageous to keep locos' brakes
from applying --- so that the train does NOT bunch-up against the slowing locos.

Normally when braking you want to keep the train stretched...like keeping a 
chain stretched ... the ability to keep the loco brakes released is crucial.
( see separate rules regarding locomotives equipped with "driver tires") .

For all circumstances, the locos brakes are applied by the 'automatic control valve" on each 
locomotive, whenever the engineer makes a, trainline, brake-pipe pressure reduction.  
However, loco brake control valves, regulate the pressure flow, to the loco's cylinders,
to allow build-up of pressure, at a slower-rate than the car brakes.  keeping the train stretched.

In virtually  every case,  the engineer activates the brake-release feature of the 'independent' 
brake valve handle to release any air pressure that may be building-up in the driver's brake cylinders.
You generally want to keep the train s-t-r-e-t-c-h-e-d when stopping.

So, you will find that every loco ( with rare exceptions --- steam actuated brakes, etc) equipped 
with both straight-air and 'automatic' control,valves... They are joined before the cylinders at
specialized, small valve called: a 'double check valve '.  The double check valve has 2 pressure
input pipes from the braking system --- a pipe from the engineer's independent  brake handle,
AND the automatic-control valve's  "application" portion.... whichever has the highest 
pressure will dominate the air flow to the cylinders.... which apply the brakes

Remember, though, the engineer will invariably realease any cylinder pressure build-up attempts,
by always releasing the accumulated pressure at his "independent" brake handle ..

W.



Edited 2 time(s). Last edit at 03/22/20 11:49 by wcamp1472.



Date: 03/22/20 09:45
Re: How you can see if the car or engine had straight or auto bra
Author: callum_out

A "double check" is simply a shuttle valve ie a single ball double seat check by which the highest pressure will move to ball to
seat against the lower pressure side. Be nice if the aur brake people had used more common industrial terms rather than making
up their own descriptions. Problems can occur when bleeding back through a shuttle as the path of exhaust can be poorly defined
by the action of the ball. You need both slides bled to get a predictable bleed. 

Out 



Date: 03/22/20 09:52
Re: How you can see if the car or engine had straight or auto bra
Author: wcamp1472

Air brake people were here, FIRST!!

It would be 'nice' if the rest conformed to air brake wording  ...

W.



Date: 03/22/20 11:08
Re: How you can see if the car or engine had straight or auto bra
Author: callum_out

Sorry, doesn't work that way, follow the money, Actually the concept of hydraulics and force amplification
long predates air brakes.

Out 



Date: 03/22/20 11:10
Re: How you can see if the car or engine had straight or auto bra
Author: cewherry

wcamp1472 Wrote:
-------------------------------------------------------
much snipping......
> "Several revisions, over the years, improved and
> changed the loco control
> devices, but even today's loco systems will apply
> the brakes to the oldest
> existing 'automatic' brakes , that may be found 
> in museums and collectors..  
> The oldest cars I've seen,  use the old K-2
> control valve.." more snipping...

To your point; while studying various air brake schedules in preparation for taking my engineer promotion
exams I was counseled by a wiser soul, who saw that I was obviously in 'over my head',  to put away all of my
fancy, colorful, confusing charts and books that described the latest versions of locomotive and train car air brakes;
at the time 26L and 24RL locomotive and ABD car brakes. The sage told me to open and study any books that
covered No. 6 locomotive and AB car control valves. 

In my ignorance I protested: "But those are old, obsolete systems". He countered that though they may be
old, every feature of those 'old' systems were contained in today's 'new and improved' versions. The new systems did
exactly the same functions, charge, apply and release locomotive and car air brakes, just with more 'bells and whistles'.

I took his advice and was amazed at how the mysteries of the basics were laid bare. 

Charlie



 



Date: 03/22/20 11:23
Re: How you can see if the car or engine had straight or auto bra
Author: wcamp1472

"....Actually the concept of hydraulics and force
> amplification
> long predates air brakes."

First explained by Archimedes, early in Greek society.
So, I guess we should be using Greek terminology.

W.

(Extra credit: What is the current name of the island that Archimedes lived on?

From memory, only, 
No going to GOOGLE!  )



Edited 1 time(s). Last edit at 03/22/20 11:28 by wcamp1472.



Date: 03/22/20 11:40
Re: How you can see if the car or engine had straight or auto bra
Author: nycman

Thanks, Wes.



Date: 03/22/20 11:55
Re: How you can see if the car or engine had straight or auto bra
Author: wcamp1472

I've tried hard to not go too deep into the weeds on the basics
of train air-brakes 

Its a fascinating subject, involving the most complex concepts in "loco 
understandings".

A similar, hard thing to understand, is what it takes to get to a "superheated 
state" in steam going to the cylinders..  
Most trips are spent running 'saturated'...

W.

 



Date: 03/22/20 15:28
Re: How you can see if the car or engine had straight or auto bra
Author: Chico43

THE ABC'S OF AIR BRAKES by C.M. Drennan. Everything you ever wanted to know about RR air brake systems in a easy to understand format.



Date: 03/22/20 15:31
Re: How you can see if the car or engine had straight or auto bra
Author: wcamp1472

Got that, too.

Drennan's books don't  cover 26L, or later "schedules .."

W.


 



Edited 1 time(s). Last edit at 03/22/20 16:56 by wcamp1472.



Date: 03/22/20 17:05
Re: How you can see if the car or engine had straight or auto bra
Author: Chico43

wcamp1472 Wrote:
-------------------------------------------------------
> Got that, too.
>
> Drennan's books don't  cover 26L, or later
> "schedules .."
>
> ​W.
>
>  

The poster who wanted an explanation of how the automatic air brakes work didn't specify any certain schedule. Drennan's books contain solid, basic information for the student.
I suppose that's why they're called the ABC"s.



Date: 03/22/20 17:47
Re: How you can see if the car or engine had straight or auto bra
Author: Elesco

Thanks to Wes, Earlk and others for interesting air brake discussions.  You got me going, now trying to understand the innards of Westinghouse Distributing Valves.  There are lots of free downloads available for expired-copyright Westinghouse No 6 air brake books and manuals.



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