Steam & Excursion > Did steam engines have dynamic brakes?

what I mean is, was there a way to direct steam pressure into devices and methods so as to oppose the loco's direction?

dragoon Wrote:
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> what I mean is, was there a way to direct steam
> pressure into devices and methods so as to oppose
> the loco's direction?

Yes. Both the D&RGW and Santa Fe used or experimented with the French designed "Lachiey Water Brake" (probably incorrect spelling).

Here's an old thread about the topic:

Water Brakes/Chappelle Brakes (trainorders.com)

dragoon Wrote:
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> what I mean is, was there a way to direct steam
> pressure into devices and methods so as to oppose
> the loco's direction?


Yes, Sorta.

Not that could be really called successful. These come quickly to mind.

Most obviously, Set reverse lever opposite direction of movement and crack throttle open a bit. Very hard on machinery of piston valve engines, or will likely lift slide valves off their seats, sucking cinders onto moving parts, abrading valve seats. Strongly discouraged.

Water brakes. Shut off the throttle, set valve gear in reverse and spray water into cylinders. Hard on machinery, but got fairly wide use around 1900 or so.

There are likely others.

Edit: To clarify. Using large amounts of water in the cylinders would cause locking, severely damaging. Instead, sprayed water would vaporize from the heat of compression, as a cushion to retard piston movement.

-LD



Edited 2 time(s). Last edit at 02/04/24 17:11 by LarryDoyle.

When the last exemptions were expended in Sept 1903 for the new Safety Appliance Act to go into full authority, three railroads refused to add brake shoes to the engines driver wheels as required.  They claimed the heat on the driver tires would loosen them and cause wrecks. Two railroads were the narrow gauge Denver & Rio Grande RR and the Colorado & Southern RR because they both used water brakes for the long down hill movement.  The third was the West Jersey & Seashore RR because they ran 80 to 100 MPH express train from Camden Wharf and Atlantic City.  The brake shoes on driver would get very hot when coming down from their high speed. 

The ICC took charge and insisted they must work out installing brake shoes on driver, and gave them one additional year to have the work done.  It is possible this was when the bail-off procedure was developed that just releases the brake application only on driver wheels. That way the engineer could still brake the entire train but keep the driver from heating too hot.
 

The "Water Brake" was thecLeChatelier brake.

elueck Wrote:
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> The "Water Brake" was thecLeChatelier brake.

That's it. The D&RGW used it to great effect, right until the end of steam.

A steam engine also would tend to pull a train on long downhills in that it was necessary to work some steam, minimally open the throttle, to keep the cylinders lubricated.    To at least mitagate this, and save some on water and fuel, Santa Fe installed drifting valves on many locos.    This can be seen as a second smaller cylinder on top of the main cylinder.    This allowed the engine to coast or drift down hill without working steam, not by any means a brake, but at least the engine would not be working steam trying accelerate in effect the train on down hills.   Other roads used drifting valves but I do not know which ones.    

The main problem with most "drifting valves" was that no lubrication 
stream is supplied to the pistons.  Remember that steam locos fitted with pump 
activated, mechanical lubricators, feed valve oil to a 'spoon' in the steam delivery 
pipes, directly over the valves controlling steam events to the pistons.

Santa Fe application allowed greater "air-shuffling" either side of the 
flashing pistons, and I don't know, specifically, how much more effective 
their devices were over the means utilized by other builders.

In general, the cylinder volumes, 'times' RPMs, far exceed the small 
'air-ports" most commonly used.  Another factor, is that a small amount of steam
rapidly fills the cylinder volumes;  whereas, air has no corresponding 'expansion 
capability', and the steam continues to carry lubricating oil to the pistons,
"air drifting valves" supply NO lubrucating oil to tbe rapidly travelling pistons.

So, yes, most skilled engineers know how to fill the cylinders with beneficial
amounts of steam, without actually 'powering' the pistons.

Modern 'front-end" throttles are far superior steam flow-control compared to
the old dome, single spool, dome-throttles.  

Front-end throttles have several, separate small-opening poppets ( available
with 5 to 7 ports and poppets).  So, it's much easier to operate with one poppet open,
and that supplies all the steam you need for lubrication carry-over,
but, with no appreciable pressure applied to the piston face, or any power into 
the train.  

Going downhill, with no cars, is a very dicey situation....since the engine's mass
is accelerating the loco.  The most effective braking comes from applying the
shoes to the driver tires.  HOWEVER!  that very quickly warms-up the tires.
..and even a small rise in tire temperature loosens the shrink-pressure when
the new tires had been applied.

Nee tires are 'warmed-up' by a ring burner used to warm and expand the 
new tire.  Once expanded the tire is quickly applied the the cold driver-center,
and the tire immediately is cooled, and shrinks onto the wheel center.

Some railroads applied several small 'clips' welded only to the driver-center,
but extending  over the tire front --- in order to keep a loosened tire from
leaving the wheel, altogether.

In order to identify a possible loosened tire, yellow paint marks are applied from
tire to the wheel center.  The yellow marks were applied at two locations on
each wheel.   If the yellow marks are moved out-of-line , that indicates the tires
had been loosened, and had moved from the original installation position.

During the 1980's GE sold ( older technology) diesel locos to Communist China,
several hundred units.  The Chinese wanted to use wheels equipped with driver tires...
GE wanted no part of applying tires to diesel locos.  So, China supplied their own
tire-equipped wheelsets.

At Potomac Yards, we inspected all those export locos, headed to Newport News, Va.
We checked those yellow 'hash-marks' and identified about 25 wheel sets,
out of all the units exported, with evidence of slipped tires.

What was unusual was that GE had fitted the export locos with MU  "Actuating"
air line hoses, which all were connected to the live, head-end hauling locos.  

For MU operation of loco air brakes, 3 hoses are connected loco to loco, in addition
to the larger Trainline airbrake hose.   When multiple units are connected the three
MU air lines ensure all trailing units' air brakes are applied, and released in unison
with the lead locomotive.  

The three hoses are labeled: "Main Reservoir", "Actuating" and "Brake Cylinder":
"Main Reservoir" connencts all the locos compressors together, and controlled 
by the lead locos..

"Actuating" air line is pressurized when the engineer operates the pressure valve 
that instantly releases engine brakes.   Actuating pressure can reach MR pressures,
if held in position long-enough.  It simply operates each units' release valve ---
to exhaust all the air from driver brake cylinders.

"Brake Cylinder" air line conveys the brake cylinder pressures to all trailing units,
to synchronize brake cylinder pressures 

Remember that loco brakes can be applied by two methods, independently
of each other.   The engineer has a smaller brake handle that applies and 
releases locomotive brakes.  Because the small valve can be freely used to
pressurize brake pistons, that pressure is "independent" of the postion of
train air brakes' handle position..

The train airbrakes operating pressures are controlled from the lead locomotive,
according to the engineers' needs to applying train brakes.

Locos airbrake systems are also equipped with their own brake control valves
that are equivalent to the control valves on trailing cars.  When the engineer
applies the train brakes, the control valves on units in the train, all apply their
loco brakes on each and every locomotive.   

MU locos, that are 'slaved'  to the lead locos, can have any trainline-activated
brake application, which can be released at any time by the engineer --
- using the 'Actuating' position of the "Independent" brake valve handle.

In the case of the Chinese export locos, the factory had equipped the export
units with only the "Actuating" MU air line connected to the lead units. 

The Chinese locos also had the main train-airline connected.  That meant that
the dead locos would have their brakes activated whenever the engineer applied
the train brakes... HOWEVER, with the "Actuating" hoses connected to the
dead locos,  their brakes would be released by the engineer, as he releases
all loco brakes.  ( Typically, dead locos main reservoirs are "trickle-charged" through a
small port, and MR pressure is typiclally limited to 45 psi maximum, when dead-in-tow. The charging action is enabled when a ‘dead engine’ toggle on the affected loco’s control valve set for
‘Dead Engine’).

STILL!  the red Chinese wheel sets were arriving at PY , with slipped tires—— yellow stripes out of alinemen’.

GE arranged with Amtrak, at Ivy City ( Washington,DC) to swap-out complete
trucks with new wheels sets, shipped by highway trailers to each defective locomotive.  
Eventually, the defective wheel sets were sent back to China, since they
were Chinese to begin with.

With the Actuating air lines connected, it is reasonable to presume that the 
tires that were loosened, & had been over-heated, solely as a result of navigating 
many curves, in succession, and NOT by normal brake operation.

Also, the defective wheelsets reveal the varying tension
achieved with the shrink fits
That's the best explanation that GE could provide. Reflecting an ineffective ‘quality-control’ system
at the plant that produced the wheel sets.

So, always look for those little yellow paint stripes, on any tire-equipped wheelsets.

Now you know!

​W.

( Another interesting fact is that the Chinese order
was NOT equipped with electrical MU connections.
China would use crews assigned to each loco, when
more than one loco was used to pull a train.
For safety they still were equipped with MU air-control lines,
so that only ONE engineer’s valve regulated train air
pressures—- there would only be ONE ‘lead-unit’.
On double-headed trainsets, all loco brakes are operated from
the lead loco, only ---- just like steamers!).




 



Edited 9 time(s). Last edit at 02/05/24 09:37 by wcamp1472.

Were there brakes on tender wheels?  

sf1010 Wrote:
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> Were there brakes on tender wheels?  

Yes. In fact, Southern Pacific 4-8-2, 4-8-4, and 4-10-2 locomotives even had brake shoes in their engine truck wheels as well as the trailing truck wheels. The SP, and UP, had a "mountain cock", located on the cab floor within reach of the Engineer's left foot, which when closed, cut-out the brakes on just the drivers. Thus, on their steep mountain grades, the independent brakes could also be applied, without using the driver brake shoes, and thus NOT overheating the driver tires.

Wes, When I worked in the Topeka Shops in the 70's, they had a big wheel shop there. They turned multi-wear wheels, smoothed up plain journals, pressed roller bearings on and off, pressed new wheels on new axles, etc. They brought in some new wheels that were stored outside about zero degrees, and pressed on new axles that were stacked inside the shop at about 70 degrees. They were put on a wheel car, and sent to Temple, TX. That car eventually derailed because a wheel had moved inward on a raised wheel seat axle, thankfully it was in a yard. The wheel press machine made a tape of each set it made. When they reviewed the tape for that day, they found that particular wheel/axle set barely made the minimium pressure required to press the wheel onto the wheel seat. When the temps normalized, the wheel had warmed up and expanded a little, and the axle had cooled so that when their temps were the same, it was not tight enough to keep it from creeping off the wheel seat going through the curves at the yard. We heard all about it at the safety meeting.

YES!

The purpose of the 'paper traces' on presses is so that the 
operators can contemporaneously compare the pressure/disatance record
of each wheel pressed.  And examine every press record & self-reject an
in adequate trace diagram.

A correct press trace-line will be a slope of pressure vs distance,
and a near perfect press will approximate a smooth, 45-degree angle.
As you would expect the pressure needed would increase as more 
of the surfaces come into contact with each other.

There are other traces indicating low pressure until the end,
some traces show high pressures to start then lower pressures.
Such improper traces condemn the wheel fit and the wheel set must be
re-machined and re-pressed, or scrapped, if not worth the time and effort.

The purpose of the paper traces is a vital quality control step to prevent 
future derailments.  Such press and forget practices are up to the wheel-shop
supervisors to catch & correct.  It's a true leadership failure, if improper presses 
are recorded, yet the defective wheel sets are sent out as ready replacements.

And, yes, temperature stabilization of the components is a CRUCIAL aspect of
correct wheel-pressing shop processes.  Some wheel shops require wheel/axle
temperature records at the time of the 'press'. Again, supervisory responsibility
about acceptable wheel shop practices.   No doubt that the above instance was one
of multiple improper wheel-presses that failed to be caught for inadequate wheel press 
recording;  yet, shop dutifully retained the wheel press records, as required.

I'd expect that today's presses have electronic recording processes and
go/no-go alarms relating to inadequate "wheel presses".

But it's up to the shop's managenent to properly supervise and train
shop folks on what are acceptable standards.

You could even institute a rewards program to encourage reporting 
faulty press records or other QC traps.  Yes, they're supposed to catch that
stuff, but sometimes appreciated rewards are an effective solution.

​W.