Subject: Locomotive Brakes:Steam or Air

From: [email-masked] (John Johnson)
Date: Tue, 30 May 1995 11:29:03

I am building a live steam locomotive (7 1/2" gauge) three truck shay.  I am 
presently working on the tender frame and have begun to think about the 
locomotive and tender brakes.  I understand that some live steamers use steam 
for braking power, instead of air which is the case for most prototypes.  
Which way should I go on this?  My locomotive will have three brake cylinders 
(one for each truck) about 1 1/2" diameter each.  Do others build a steam 
powered air compressor to provide air for the brakes?  If I were to use 
steam, what problems would I have to design around?  With steam, how do you 
deal with condensation in the brake line and cylinder?

John D.L. Johnson
California State University, Chico
[email-masked]

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From: [email-masked] (J.R. Stoner)
Date: Tue, 6 Jun 1995 23:58:17 GMT

In article <[email-masked]>,
Tim Kirby <[email-masked]> wrote:
;Depending on the size of the locomotive air may be viable, however my
;experience is that steam is more common for the locomotive.

In my copy of the book "So You Want to Build a Live Steam Locomotive",
There is an article about using a car fuel pump as a vacuum pump for a train
brake hose.  Instead of air pressure gradient above ambient releasing the train
brake there is a partial vacuum to release the brake.  Bleeding air into the
train line sets the brake.  The first benefit (in my opinion) is setting the
train brake is much faster than its release, as a safety measure.  The other
benefit is a mechanically simple fitting on the brake hose between cars,
though there is nothing to prevent a scale-sized glad hand for appearance sake.
to 

;Of course, don't forget some sort of manual braking capability - if nothing
;else, you want to be able to lock the thing solid when it's sitting in
;the steaming bay cold...

Typical practice is to chock the wheels, then release the independent air
so the driving wheel brake shoes will not freeze onto the tires.  Then dump
the fire and let the poor machine have a nap.
>
>Tim
>--
>Tim Kirby                    - [email-masked] -                +1-(612)-683-5390
>Software Division System Support ________________ Cray Research, Eagan MN, USA
>----------------- Ask not for whom I speak - I speak for me ------------------
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>you are hopelessly confused...                                - Walter Mondale

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From: [email-masked] (Tim Kirby)
Date: 7 Jun 95 22:12:10 CDT

J.R. Stoner ([email-masked]) wrote:
: In my copy of the book "So You Want to Build a Live Steam Locomotive",
: There is an article about using a car fuel pump as a vacuum pump for a train
: brake hose...

If you want to run vacuum brakes it's easier to build an ejector... there's
nothing to it.

: Typical practice is to chock the wheels, then release the independent air
: so the driving wheel brake shoes will not freeze onto the tires.  Then dump
: the fire and let the poor machine have a nap.

I can't say I've seen any cases of frozen brake shoes on model live steamers
in the 30 years or so I've been involved with them. Chocks are easily removed
by accident. A screw down manual brake takes deliberate effort. It's quite
sufficient to have it on the tender...

Tim