"Setting a retainer"

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"Setting a retainer"
Posted by Murphy Siding on Thursday, November 10, 2005 10:31 PM
What does this mean in relation to train brakes?

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Posted by Anonymous on Thursday, November 10, 2005 10:40 PM
When the air brakes are released on a car, the pressure in the cylinder that provided the braking effort has to be exhausted to the atmosphere.

This air passes through a small valve called a retainer, which has four positions. The normal is called release, which allows the exhaust to pass directly to the atmosphere. The other positions allow some of the pressure to be "retained" in the brake cylinder, which means that the brakes on the car are still on even though the control valve is in release position and the brake reservoirs are being recharged from the brake pipe. These other positions yield varying rates of exhaust of the air from the cylinder, according to the conditions to be dealt with.

The retainers have to be set up by hand, and are used on long grades to keep the brakes on the cars - and the train from running away - while the reservoirs are recharged for the next brake application.

They're "turned up" (set to retain) before descending the mountain, and are "turned down" at the bottom, for normal operation.

They're a great safety device - ask any mountain hogger.

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Posted by Murphy Siding on Thursday, November 10, 2005 10:45 PM
Set by hand? Some poor guy has to walk the length of the train and do this before and after the trip down the mountain?

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Posted by Anonymous on Thursday, November 10, 2005 10:51 PM
Yep! Hard work, on mountain grades brakeman really had a job. The main reason for using retainers is to allow the brake compressor recharge without having to reapply the brakes before it can do so.
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Posted by kenneo on Friday, November 11, 2005 4:33 AM
To fully understand this concept you have to know how the Westinghouse Automatic Air Brake system operates. The most simple answer is that to release the brakes, you pump up the air, and to set the brakes, you lower the air pressure. In that way, if the train does come apart, the brakes will automatically apply.

As Old Timer stated, there are various levels of "release" available going all the way from a rather quick 10 minutes "of braking power" to absolutely no release whatsoever. This system was used prior to dynamic braking or when dynamic is not available and usually requires a caboose with a brakeperson riding in it. At the point where the extra braking power is needed, the train comes to a complete stop and the engineer puts gives a full set (23 lb reduction for frieght and 43 lbs for passenger) and the brakeperson goes forward turning up the retainers as instructed by the conductor. This is always done from the rear forward and usually is done on every other car.

When the brake person is done and back on the caboose, the engineer sends back a release, which releases the brakes on the cars with the retainers turned down and keeps the full set on the other cars (turned up). The train is then started and continues on for a set period (either time or distance, but usually a combination of both) that is short enough not to let the wheels get to hot, where the train is stopped, the retainers that had been turned up are now turned down and the other retainers are turned up. This process is repeated as often as necessary and permits wheel cooling while the train is in motion rather than waiting for 15 to 30 minutes for a standing cooling period.

With the arrival of the "Lap" position on the brake valve and the Pressure Maintaining Brake this practice was reduced greatly - in most areas it disappeared completely. The engineer was able to do the retainers job with the train air, but it was to all cars or to no cars, and rolling cooling was usually not permitted. The arrival of Dynamic Braking let the engine itself provide braking power without any mechanical brake application.

Just to make a last note, the name "Retainer" or "Retaining Valve" comes from the action of "retaining the brake application while the brakes are released". Not the contridiction of terms it may appear.
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Posted by jchnhtfd on Friday, November 11, 2005 7:33 AM
Lovely explanation Eric! The only thing I might add is first that retainers -- either by hand or by various more sophisticated on-car equipment -- are still used on some grades, and if they are required, somebody has to walk the train to check them. Second, while dynamics are usually used instead, when figuring the power required and braking available for a train, you are not permitted to factor in the dynamics. Either the train has enough air brakes, or she doesn't roll. There have been several really bad accidents in the past where the dynamics failed for one reason or another, and the train got away.
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Posted by kenneo on Friday, November 11, 2005 9:00 AM
Jamie -- now, could you just be learning things?????[:D]

On the "Good Olde Friendly" it was "TOPB" -- Tons per Operative Brake, and every grade too steep to stop a car with only a hand brake had a "TOPB" assigned. It said so in the Special Instructions.
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Posted by Modelcar on Friday, November 11, 2005 9:49 AM
Wow....What a complicated bit of data.....I've listened to these explainations for years and still have a muddy understanding of what it's all about. It almost sounds like the train is stopped to manually set these "retainers" to overcome a deficiency in the brake design. Several years back and a couple in a row we stopped each Spring on the way back from Florida...at Saluda, NC at the famous NS grade and talked to people of their famous "hill", etc....and learned that was one procedure that took place there in the town of Saluda..{the grade summit}. Before the crew would even think of starting down the grade the retainers had to be set....So it was mandatory to do this on that hill...dynamics or not. I suppose I just don't quite understand why a brake application from the engineer couldn't accompli***he same thing....Is there a danger of the brakes becoming party released as the train would make it's decent of the hill and hence "turning up the retainers manually prevents this...." ? I know this "hill" would require major breaking power as it was, {is}, a 4.7% grade in general for several miles.....Any thoughts...?

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Posted by jchnhtfd on Friday, November 11, 2005 9:58 AM
QUOTE: Originally posted by kenneo

Jamie -- now, could you just be learning things?????[:D]

On the "Good Olde Friendly" it was "TOPB" -- Tons per Operative Brake, and every grade too steep to stop a car with only a hand brake had a "TOPB" assigned. It said so in the Special Instructions.

Good heavens yes! I'm always learning things! One of the best reasons to read these forums![:D] And you'd be surprised (well, maybe you wouldn't...) how often I find out I've been wrong or misunderstood something...[:)]
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Posted by TomDiehl on Friday, November 11, 2005 10:36 AM
QUOTE: Originally posted by Modelcar

Wow....What a complicated bit of data.....I've listened to these explainations for years and still have a muddy understanding of what it's all about. It almost sounds like the train is stopped to manually set these "retainers" to overcome a deficiency in the brake design. Several years back and a couple in a row we stopped each Spring on the way back from Florida...at Saluda, NC at the famous NS grade and talked to people of their famous "hill", etc....and learned that was one procedure that took place there in the town of Saluda..{the grade summit}. Before the crew would even think of starting down the grade the retainers had to be set....So it was mandatory to do this on that hill...dynamics or not. I suppose I just don't quite understand why a brake application from the engineer couldn't accompli***he same thing....Is there a danger of the brakes becoming party released as the train would make it's decent of the hill and hence "turning up the retainers manually prevents this...." ? I know this "hill" would require major breaking power as it was, {is}, a 4.7% grade in general for several miles.....Any thoughts...?


It's all related to recharge time of the brake reservoir. If the brakes are set and released several times in quick sequence, the air pressure in the braking reservoir will be drained and have no time to recharge. That would cause a total loss of braking power. Not a design flaw as much as a design limitation. One requirement for train air brakes on cars to be used in interchange is that it be operationally compatable with all previous braking systems. In theory, the oldest train air brake system will work with the newest, but may not have some of the features of the newer system, like stepped application.
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Posted by kenneo on Friday, November 11, 2005 10:36 AM
QUOTE: Originally posted by Modelcar

Wow....What a complicated bit of data.....I've listened to these explainations for years and still have a muddy understanding of what it's all about. It almost sounds like the train is stopped to manually set these "retainers" to overcome a deficiency in the brake design. ... ...at Saluda, NC ... ... Before the crew would even think of starting down the grade the retainers had to be set....So it was mandatory to do this on that hill...dynamics or not. I suppose I just don't quite understand why a brake application from the engineer couldn't accompli***he same thing....Is there a danger of the brakes becoming party released as the train would make it's decent of the hill ...........


A full and complete stop MUST be made to either turn retainers up or down. Depending upon your Companies Rules or the Special Instructions, you may also be required to do a "blow and go" (set and release brake test). Retainers do not correct any deficiency as such but alter the way a brake application and its release are handled by the cars so as to keep the brakes applied on some cars and not on others when the engineer has released the brakes.

The problem comes in several pieces and can get a bit complicated, so I will try to keep it very simple - and thus not quite complete![:0]

As I mentioned in a post above, it takes an increase of air pressure to release brakes, and the locomotive can only pump a specific amount of air in a given period and the brake pipe can only handle a certain specific amount of air in a given period.

That means that there will be a delay - both in releasing and setting the brakes and also in charging the air resevoirs on the each car as well as each locomotive. The resevoirs MUST be fully charged to have a proper brake application. And to charge the resevoirs, the brakes must have fully released, so there needs to be a method of keeping the brakes applied while the recharge function is being accomplished.

And that is what a retainer does. It retains the application on its own car by not permitting the recharge air from entering the brake piston until the resevoir has been recharged or lets the brake release slowly during the recharge process if turned up only partly. As a result, the train stays under control. Well, it's supposed to - and will if done properly.
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Posted by Anonymous on Friday, November 11, 2005 11:02 AM
QUOTE: A full and complete stop MUST be made to either turn retainers up or down.

I read a book about a lumber company. In a story from a brakeman about retainers, they used to keep the train rolling (crawling) as the retainers were released, and they worked from the front of the train to the rear when doing so.
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Posted by route_rock on Friday, November 11, 2005 11:19 AM
Ok old head trick for you. Lets say your train is held waiting for something and a guy in the pool leaves before you ( for some reason this is BAD BAD BAD I think let em run around me I get to stay home longer)and you dont want that. So you take a broom handle and whack the retainers as the train is pulling by you. Retainers set up and at the first TWD that calls for them to " stop your train. sticking brakes on axle 488" you run around them waving and smiling and hoping they dont have a broom ready for you.

Yes we are on time but this is yesterdays train

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Posted by Modelcar on Friday, November 11, 2005 1:56 PM
Eric: Understand recharging needs for each reservoirs, etc....but on a grade such as I mentioned @ 4.7% or more....I would imagine an engineer would not be charging the brake line to do any brake releasing......Wouldn't he want those brakes to drag all the way down that excessive grade....

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Posted by Murphy Siding on Friday, November 11, 2005 6:33 PM
The book I'm reading talks about retainers and a runaway UP train on the Cima Hill in 1980. Thanks for the information.

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Posted by Anonymous on Friday, November 11, 2005 6:37 PM
What happens is an engineer will tend to put on just a little too much break, now you would set you brakes and adjust speed with the dynamics, back then if you put too much on, you had to release, and recharge. If you didn't you would roll to a stop. All the brakes work, some of them just continue to apply when released.
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Posted by Modelcar on Friday, November 11, 2005 8:59 PM
...On the grade I'm referring too I believe we'd not see "too much" brake being used....That grade of 4.7% plus with a loaded train is excessive.....I don't think there is too much concern of rolling to a stop decending on that grade. At one time the "hill" contained 2 runaway tracks and just a few years ago when it was embargoed it still had an operational runaway escape track...!

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Posted by kenneo on Saturday, November 12, 2005 6:43 AM
QUOTE: Originally posted by Modelcar

Eric: Understand recharging needs for each reservoirs, etc....but on a grade such as I mentioned @ 4.7% or more....I would imagine an engineer would not be charging the brake line to do any brake releasing......Wouldn't he want those brakes to drag all the way down that excessive grade....


That is exactly what retainers do. They keep the brakes applied while the air is recharged.
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Posted by Modelcar on Saturday, November 12, 2005 6:52 AM
..One thing I didn't hear in talking to residents of the little summit town of Saluda....When the train is stopped at the top of the "hill".....I don't know if ALL of the cars had the retainers set....In my opinion just observing the steepness of the grade..{it's hard to believe it's a railroad on that grade}, one would think each car, especially if loaded would need it's retainer...."set"...{In all the visits, I never got to witness this operation....even after waiting for up to 4 hrs..}.

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Posted by TH&B on Saturday, November 12, 2005 7:35 AM
Are there any other grades (since Saluda is mothballed so it is not in use today) that require the use of retainers regularly? I can only think of one grade in use today and retainers are only required if the train stops while going down the hill, then some retainers need to be set before moving. This is a rare occurance as trains don't stop here.

I know of abandoned lines that required retainers on all downhill trains, but are there any lines that would use retainers regularly in use today???


ps; I have seen some old Southern Pacific refers or box cars that had the retainers up high with the hand brake wheel. Does this sugest that the brakeman adjusted the retainers while running across the roofs while the train was moving? Most cars had them located to reach from the ground.
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Posted by kenneo on Saturday, November 12, 2005 7:38 AM
QUOTE: Originally posted by Modelcar

..One thing I didn't hear in talking to residents of the little summit town of Saluda....When the train is stopped at the top of the "hill".....I don't know if ALL of the cars had the retainers set....In my opinion just observing the steepness of the grade..{it's hard to believe it's a railroad on that grade}, one would think each car, especially if loaded would need it's retainer...."set"...{In all the visits, I never got to witness this operation....even after waiting for up to 4 hrs..}.


Depends on the Company Rules and the Special Instructions. Variabilities include cars with in-operable brakes, per-cent of the grade, curvature, distance for retainer use, weight of the train (remember Tons Per Operable Brake?), dynamic abilities of the locomotives among some of the considerations.

And, just to add a little confusion for you, although the retainers would normally be turned up at the top of a grade, that may not be the case. It has been known for crews to be required to use retainers going up a grade as well as down (really rare), and if a crew is waiting for another train someplace over the other side of the retainer district, they can turn up the retainers there, but if they do and they need to use the brakes prior to the summit, the brakes on the cars that have been turned up will stay applied and probably stall the train.

AND ... If the lead unit of the train has its brake system incorporating the pressure maintaining function (all units built new in the last 25 or so years -- at least --) may not be required to use retainers. As I remember, Saluda is pretty short and I think that a stop for wheel radiation or resetting of the retainers would not be required. All that would be required in this case is a "blow and go" or a running test.
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Posted by Modelcar on Saturday, November 12, 2005 7:48 AM
...I certainly don't have an answer to the above question...Recently in articles of some of the "passes" out on western lines {and I'm not sure if that one is still operating...but I believe it is...the Raton Pass...was mentioned to have grades of up to 4%....I would think retainers might have or still would be envolved on that down grade...but I for sure dont' know....I don't remember any conversation about retainers on the eastern roads in the area I originate from...Ex. B&O and Pennsylvania....and near by B&O banches with grades of up to 3%....And back then was before any dynamic brakes...And those were heavy trains....Hauling coal.

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Posted by kenneo on Saturday, November 12, 2005 7:54 AM
QUOTE: Originally posted by 440cuin

Are there any other grades (since Saluda is mothballed so it is not in use today) that require the use of retainers regularly? I can only think of one grade in use today and retainers are only required if the train stops while going down the hill, then some retainers need to be set before moving. This is a rare occurance as trains don't stop here.

I know of abandoned lines that required retainers on all downhill trains, but are there any lines that would use retainers regularly in use today???


ps; I have seen some old Southern Pacific refers or box cars that had the retainers up high with the hand brake wheel. Does this sugest that the brakeman adjusted the retainers while running across the roofs while the train was moving? Most cars had them located to reach from the ground.


Until diesels and dynamic brakes, the brakemen could be required to "decorate the tops" (climb up onto the car roofs to operate brakes) to operate the handbrakes or the retainers. This was not really safe (for several reasons) but since all that was available for communication was the hand signal or the locomotive whistle, it was the safest method available.

Retainer rules (and also the retainers!) still exist so that trains can be safely operated down "steep" or long descending grades without dynamic brakes or pressure maintaining system of the air brake being operable.

The classic example of this is the runaway that the SP had that derailed outside of West Colton dumping the entire train (including the helpers) and killing a bunch of people. Had the crew known the true weight of the train and the true numbers of in-operable dynamic brakes, they would have turned up the retainers and we would have never known about these people.
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Posted by Modelcar on Saturday, November 12, 2005 7:55 AM
...Eric...You may be familiar with what Saluda looks like and if so...you might agree it's hard to understand how anything could be pulled UP that grade with some retainers set....
By the way, Saluda grade: Several miles.

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Posted by kenneo on Saturday, November 12, 2005 9:35 AM
Perhaps I should clarify on using retainers while ascending. It was to keep the train from rolling back when the trainling weight behind the road locomotive exceeded the holding power of the independent (engine) brake. Prior to release of the brakes, retainers would usually be turned up to hold the train during release and equalization should the situation exist for their need. This procedure was really a "knuckle buster" and "harassment" if you didn't really need it because the rear men (Conductor and Rear Brakeman) would be running up and down the rear of the train turning retainers up and then down just to keep the train from rolling back, and then once moving, so that the train would not stall. It was plan "Z".
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Posted by Anonymous on Saturday, November 12, 2005 10:00 AM
Huh? Wouldn't the retainers make the train more likely to stall on the way up?[%-)]
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Posted by kenneo on Monday, November 14, 2005 2:57 AM
QUOTE: Originally posted by Lotus098

Huh? Wouldn't the retainers make the train more likely to stall on the way up?[%-)]


Read the last two sentences again. It is either use hand brakes to hold the train or retainers. Either way, the rear end crew runs up and down the train like track stars turning the retainers up and down or tying and releasing hand brakes. And trying not to get left behind.

Also, forgot to mention -- this manuver is nearly impossible to accomplish with only a head end crew.
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Posted by Modelcar on Monday, November 14, 2005 8:31 AM
Question: I've seen images {and personally been there to see it}, of heavy {coal trains}, decending Horseshoe Curve grade down into Altoona with smoke billowing from brake shoes of the train approaching....Have not heard any stories of the train stopping to "set retainers" before decending that {12 mile}, grade....What is the difference...Some grades, set retainers and others not...If the train would get away on H S grade it would be just as dangerous as perhaps some other downgrade....So if brakes work satisfactory controlled by the engineer in that case why don't they work as well {controlled by the engineer on some steeper grades}...?

Quentin

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Posted by Isambard on Monday, November 14, 2005 10:23 AM
Page's 93 through 101 of the April 2004 issue of Trains describe getting a train down a mountain grade-pictures and an explanation and illustration of air braking systems too.
[:)]

Isambard

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Posted by Modelcar on Monday, November 14, 2005 11:13 AM
...Yes I know I have that issue on mountain railroading and breaking concerns....

Quentin

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