Speculation --- For chain connected hand brakes. Application on a hot day and released on a cool night. Releasing brakes might be a problem ? Now take the opposite - Apply on a cool night and what happens on a hot / warm day ? Is that why the number of applied hand brakes seems to be large ? Just speculation !
Then there is the brake rigging itself. For Some one who knows how it is designed does the design cancel out the effects of thermal expansion ?
Overmod, with your mention of titration you bring back memories of '55-'56 to me, as I titrated an acid with a base, adding a little base at a time until I had neutralized the acid (or I neutralized a base with an acid), looking for the indication that I succeeded. (By the way, I had an A in the quantification course.)
Certainly, no conductor would tighten one brake and ask for the test and if it failed then tighten another...until he had tightened enough to hold the train.
Johnny
I could have been clearer. 'That point' does refer to 'that very point' in the preceding sentence, a pretty clear antecedent, but I see why it has Euclid confused.
In the example, it would correspond to one car of a train in which all other cars requiring securement are also tightened to just the point where the TRAIN as a whole just barely fails the push/pull test. (Euclid seems to think just one brake being more fully applied would make that train become 'legal', which would technically satisfy securement 'rules' and incidentally demonstrate a trivial case of the argument I was making but which would NOT be safe, so I don't want to use that example.
What I intended to mean is a bit more like a thought experiment. Assume or 'posit' that by some miracle the 'necessary' number of handbrakes needed to hold the train have been applied but only enough, and equally enough, that the SUM of their equal sets would be just at the 'cusp' between passing and failing the push/pull test. That is the point in question, and it does not matter how much or little 'work' the crew, or the air brake, or Snow White's helpful forest creatures, might have done in winding the handbrake on to that point in its application PER CAR. All the meaningful 'work' that actually starts securing the train starts when any given one of the handbrakes then starts to be tightened, and it ends when all of the brakes are applied as tight as a good crew could make them.
In actual practice of course the crew would start tying down brakes from the head end back until they think they have "enough" either to hold the train or satisfy a number-of-brakes rule, whichever is the greater. Then they let off whatever air or power combination had been applied to hold the train, and conduct the push/pull test. If it fails they will set more, but I doubt it would make sense to 'titrate' the application brake by brake, pull-testing after every one until the train 'just' doesn't move.
Now that last point is critical to the Lac Megantic trial, because at least two of the Three Stooges had extensive experience on railroads with clear increase in 'number of handbrakes' for consists on a range of grades. The tables involved were, I think, in the TSB report, and I had the strong impression they represented a significant factor of safety, not just one or two brakes more than would pass the pull test applicable on nearly-level track.
tree68 Euclid What do you mean by "that point"? If I may speak for Overmod - the break-even between not enough brakes and enough brakes... As for using an application to assist with setting the brakes - usually, especially on a grade, the train will have an application on to hold it in place until the hand brakes are set anyhow. It's not like the application is being made solely to assist with applying the hand brakes.
Euclid What do you mean by "that point"?
If I may speak for Overmod - the break-even between not enough brakes and enough brakes...
As for using an application to assist with setting the brakes - usually, especially on a grade, the train will have an application on to hold it in place until the hand brakes are set anyhow. It's not like the application is being made solely to assist with applying the hand brakes.
I thougt in referring "that point", Overmod meant the point where one handbrake is fully tightened, fully set, or fully secured; and not refering to the point where enough handbrakes are set to pass the pull test, in which case the entire train is "fully securred." But I don't comprehend his last post on this matter where he refers to "that point". I assume it is a point where the handbrake is fully set.
I believe the point he was making is that when a number of handbrakes have been set, they are providing their full potential braking ability. I don't think they are because there is nothing in the windup that indicates when to stop. That is a judgment call that varies from person to person. And that leads back to the point I made when responding to Dave Klepper earlier.
EuclidWhat do you mean by "that point"?
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
OvermodOnly the additional set past that point 'counts' as securement, and that additional set will always culminate in the same pull to 'failure' to give the same resistance on pull test.
What do you mean by "that point"?
Read my lips: it's only the final securement that matters to the brake being set. All the 'work' done up to the very point the car stops rolling when push/pull tested is incidental, a bit like when making steam the way you heated the water to saturation temperature doesn't matter -- any way you get there, it 'counts' the same as inadequate securement. Only the additional set past that point 'counts' as securement, and that additional set will always culminate in the same pull to 'failure' to give the same resistance on pull test.
Overmod Does not matter how much or little work went into winding up and binding the foundation on. The ONLY thing that creates full securement is a full sustained pull for at least a second or two that produces no additional rotation or lever action. It is not some little Caspar Milquetoast 'tug' that is involved.
Does not matter how much or little work went into winding up and binding the foundation on. The ONLY thing that creates full securement is a full sustained pull for at least a second or two that produces no additional rotation or lever action. It is not some little Caspar Milquetoast 'tug' that is involved.
Does not matter how much or little work went into winding up and binding the foundation on. The ONLY thing that creates full securement is a full sustained pull for at least a second or two that produces no additional rotation or lever action. It is not some little Caspar Milquetoast 'tug' involved.
OvermodWinding on the handbrake after a power set is not 'replacing manual force with power force'; it's merely reducing the work done in taking the slack out of the linkage.
Isn't "replacing manual force with power force" the same as "reducing the [manual] work done"?
Also, winding up a handbrake involves more than just taking the slack out and them making a final tug to get tight. There is an intervening prolonged phase of winding tighter and tighter for several turn as the rigging is stretched to the final sufficient pressure.
EuclidIt would be easy to blur the distinction between setting with just enough manual force, and setting with insufficient manual force because of the feeling that manual force is being replaced by the aid of power force, and therefore, less manual force is needed
Yes, but does anyone actually setting a railroad handbrake actually think that?
Winding on the handbrake after a power set is not 'replacing manual force with power force'; it's merely reducing the work done in taking the slack out of the linkage. This might be compared to opening the compression relief when starting a combustion engine to allow the preluber to pressurize the oil to the bearings and eliminate any chance of hydrolocking, but closing it when you need compression heating in the actual start. As tree68 said, the ONLY act of securement is the final 'pull to where you can't pull no more', what the resistance training community calls working to failure. It doesn't matter how easy or hard it was to wind the gear up to that point, except peripherally that your arms may be tired from repetitively winding out the slack if the air hadn't preloaded the set and therefore made overall work less ... but that's opposite to the point you were making.
Some people may as you note have gotten into a habit of spinning an air-set brake just to firmness (perhaps reasoning that when the air is released there will be some spring action in the foundation that binds the wheel when it comes time to release the handbrakes). That is in my opinion a demonstrably bad habit, and other posters have provided some of the reasons why.
However, the rule that 'applies in all cases' (pun not intended, but on reflection not too bad) HAS to be to wind the brake on as firmly as you can, and no matter how air is applied that works out 'as hard as you can pull (or pump) before you can't move it further'. Period.
Note that this leaves open the part of a rule that says you can or can't use your brake stick as a lever when you RELEASE a binding set. I think this is resolvable by design of stick (I get the impression that some of the longer ones would bend before the set broke loose, and that might wind up Costing The Company Money). But I see nothing confusing or impracticable about one rule governing set and a different one for release.
I think most railroaders are too concerned about safety to fall into the real trap that you suggest. That is because railroads in general do have a safety culture, and that is one area where the railroaders do not take shortcuts.
That was my impression over the whole period of knowing and at times working with railroaders in the USA 1952 - 1996.
They will willingly apply the maximum pressure that does really cause pain or a lingering strain in the muscles.
[quote user="daveklepper"]
Euclid daveklepper Logically then, using air and then applying hand-brakes results in stronger brake application. With air assistance, why would people not be inclined to reduce their handbrake effort below what is acually needed because they feel that air has already done the work? That would get into the exact same area of relying of air brakes being set to supplement securement by handbrakes, although it would arrive at that risky result by a slightly different route. Quote above, Euclid Euclid, would it not be just the opposite? If going to the final turn, pull, or push is easy, would not you have more energy left for the final turn, pull or push, than if you already spent a lot of energy getting to thst point?
daveklepper Logically then, using air and then applying hand-brakes results in stronger brake application.
With air assistance, why would people not be inclined to reduce their handbrake effort below what is acually needed because they feel that air has already done the work? That would get into the exact same area of relying of air brakes being set to supplement securement by handbrakes, although it would arrive at that risky result by a slightly different route.
Quote above, Euclid
Euclid, would it not be just the opposite? If going to the final turn, pull, or push is easy, would not you have more energy left for the final turn, pull or push, than if you already spent a lot of energy getting to thst point?
Dave,
I think it might work as you say for some people. But in many cases, people will want to do as little work as possible. That is the point of using air brakes set during the setting of handbrakes. So once you start down the road of reducing labor by setting with air applied, it would be easy and likely to rationalize that further reduction of labor can be obtained by the perception that you set brakes harder with the aid of air than you would set them without the aid of air. Since there is no actual indicator of when the brake is fully set, this would be an easy rationalization to make.
It would be easy to blur the distinction between setting with just enough manual force, and setting with insufficient manual force because of the feeling that manual force is being replaced by the aid of power force, and therefore, less manual force is needed.
[quote user="Euclid"]
Euclid tree68 Euclid tree68 If the consist passes the roll test, I'm good. Not if you did not set enough to meet the minimum number of handbrakes required in the special instructions. I covered that - in the same post. Other than specific guidance regarding how many brakes should be set under various circumstances (covered in the requisite railroad rulebooks), if one car will hold the train, it meets the portion of the requirement that enough hand brakes must be set to hold the train. Okay, I see that now. Passing the test would be all you need to secure the cars.
tree68 Euclid tree68 If the consist passes the roll test, I'm good. Not if you did not set enough to meet the minimum number of handbrakes required in the special instructions. I covered that - in the same post. Other than specific guidance regarding how many brakes should be set under various circumstances (covered in the requisite railroad rulebooks), if one car will hold the train, it meets the portion of the requirement that enough hand brakes must be set to hold the train.
Euclid tree68 If the consist passes the roll test, I'm good. Not if you did not set enough to meet the minimum number of handbrakes required in the special instructions.
tree68 If the consist passes the roll test, I'm good.
Not if you did not set enough to meet the minimum number of handbrakes required in the special instructions.
I covered that - in the same post.
Other than specific guidance regarding how many brakes should be set under various circumstances (covered in the requisite railroad rulebooks), if one car will hold the train, it meets the portion of the requirement that enough hand brakes must be set to hold the train.
Okay, I see that now. Passing the test would be all you need to secure the cars.
My goodness, Larry, you satisfied Euclid. Amazing.
Euclid Also discussed was hanbrakes that wind up in a way that convinces the operator that he has a good set, while the brake acually has very little set.
Anyone that has spent any time as a railroader knows this. That's why you always test your brakes.
It's been fun. But it isn't much fun anymore. Signing off for now.
The opinions expressed here represent my own and not those of my employer, any other railroad, company, or person.t fun any
IF TTSI specify a number. Not all do.
Never too old to have a happy childhood!
tree68If the consist passes the roll test, I'm good.
EuclidAs a sidebar, the TSB did a report on another wreck in which they analysed this issue of how tightly a handbrake should be set to achieve its expected performance as "fully set." They cited a bewildering number of variables covering the matter, including many issues of wear and age affecting the mechanism of handbrakes. Also discussed was hanbrakes that wind up in a way that convinces the operator that he has a good set, while the brake acually has very little set. As I recall, this was in a report on another runaway of a cut of cars that had been tied down in a yard with handbrakes.
If I wind up a hand brake to the point that I can't pull it any more (and I'm not a 97 pound weakling) and it still won't hold the car, I'm going to notify mechanical.
If I wind up all of the handbrakes to the point that I can't pull them any more, and they still won't hold the train, there are other issues.
We have places where one lightly set hand brake will hold a train just fine for a brakes released hold test. And we have places where we simply set all of the cars (usually four, maybe five) simply because the location is not a place we want the train to get away. Better safe than sorry.
As I noted earlier, different crew members have different ideas of what's tight enough.
For now, until they issue me a torque wrench and a table showing the proper torque for each car, they're gonna get pulled as tight as I can get them, then one more tug.
If the consist passes the roll test, I'm good.
tree68A recent private passenger car movement on our line brought out the difference between clasp brakes and disc brakes. More hand brakes were required to secure the train than would have been required for a similar train with all clasp brakes... Don't ask me why - I don't have an answer, and I doubt anyone else here does, either... Besides, it's not germane to the issue at hand.
Clasp brakes are analgous to drum brakes on automobiles - a large shoe area being applied to the internal surface of the drum. In railroading you have a relatively large brake shoe area applying against the tread of the wheel and at least on freight cars the brake is applied to each wheel of the car.
Disc brakes have a rather smaller brake material area applying pressure to the disc. I don't know enough about passenger cars to know if hand brakes apply to all wheels on the car, one truck of the car or one wheel set of the car.
While the issue of disc vs. clasp is not germaine to Lac Megantic, the issue of how many wheels the hand brakes are applied against is germaine. The locomotive hand brakes only applied on one truck and had roughly half the holding power that car hand brakes, that applied on all wheels, provided.
tree68 Euclid And yet, the tables do indeed call for different numbers of handbrakes according to whether they were are set with or without airbrake assistance. Therefore, the recommendation in tables does indeed assume that handbrakes set by humans without air brake assistance will be less than fully set. Do you have a link to those tables? This is getting into the realm of when warning signs take effect. I have never seen any reference to how much torque must be applied to "fully set" a hand brake. The key is not how tightly the brake is set, rather whether the hand brake is sufficiently set to hold the car (or cars). Our rules require "enough hand brakes to secure the train from moving." A recent private passenger car movement on our line brought out the difference between clasp brakes and disc brakes. More hand brakes were required to secure the train that would have been required for a similar train with all clasp brakes... Don't ask me why - I don't have an answer, and I doubt anyone else here does, either... Besides, it's not germane to the issue at hand.
Euclid And yet, the tables do indeed call for different numbers of handbrakes according to whether they were are set with or without airbrake assistance. Therefore, the recommendation in tables does indeed assume that handbrakes set by humans without air brake assistance will be less than fully set.
Do you have a link to those tables?
This is getting into the realm of when warning signs take effect.
I have never seen any reference to how much torque must be applied to "fully set" a hand brake.
The key is not how tightly the brake is set, rather whether the hand brake is sufficiently set to hold the car (or cars). Our rules require "enough hand brakes to secure the train from moving."
A recent private passenger car movement on our line brought out the difference between clasp brakes and disc brakes. More hand brakes were required to secure the train that would have been required for a similar train with all clasp brakes... Don't ask me why - I don't have an answer, and I doubt anyone else here does, either... Besides, it's not germane to the issue at hand.
Yes, it is true that the tables are just reference guides that defer to the actual pull test to verify if enough handbrake retardation is applied. Although, I believe the tables do set minimum numbers. I would have to study them again, but I believe the minimum numbers of handbrakese have to be set even if less would pass the pull test. How tightly the handbrakes are set does enter into the compliance with the minimum numbers of handbrakes required, since that condtion has to be met regardless of the pull test confirmation. So this leads to the question of how tight is tight enough to comply with the call for a handbrake to be "set".
The tables are in the TSB report of the Lac Megantic wreck. Actually, the tables allowed Harding to set fewer than the basic minimum to be applied if no air is set. He was allowed to set fewer handbrakes because he had some air set during the handbrake application. I recall that this was detailed in the report.
I think this is germane to the the overall topic of the Lac Megantic wreck, although maybe not a pivotal issue.
As a sidebar, the TSB did a report on another wreck in which they analysed this issue of how tightly a handbrake should be set to achieve its expected performance as "fully set." They cited a bewildering number of variables covering the matter, including many issues of wear and age affecting the mechanism of handbrakes. Also discussed was hanbrakes that wind up in a way that convinces the operator that he has a good set, while the brake acually has very little set. As I recall, this was in a report on another runaway of a cut of cars that had been tied down in a yard with handbrakes.
EuclidAnd yet, the tables do indeed call for different numbers of handbrakes according to whether they were are set with or without airbrake assistance. Therefore, the recommendation in tables does indeed assume that handbrakes set by humans without air brake assistance will be less than fully set.
Why do some doctors rely on Tylenol and other doctors rely on Asparin?
My carriers TTSI state HAND BRAKES. There isn't any reference to air being applied or not. Just like with doctors, there is no real concensus of OPINION on the subject.
Somewhere, there is a definition of what is required to achieve a fully set handbrake. Because there is no physical endpoint to the tightening procedure until the chain breaks, “fully set” must be defined in mechanical engineering terms of chain pull.
Therefore, I assume that handbrakes required for train securement, as recommended in tables, are considered to be “fully set” according to the manufacturer’s specification that defines “fully set.” Otherwise it would make no sense to call for a number of handbrakes without having the handbrakes defined by their retarding ability. It is the retarding ability that counts. Without that being known, the number of handbrakes set is meaningless.
So here is the point: A fully set handbrake is a fixed measure. It makes no difference to that measure whether the brake is fully set with or without air assistance. So logically, the number of handbrakes recommended in tables should NOT vary according to how much human effort is put into to them or whether that human effort is aided by power of set air brakes. A “fully set” handbrake is a fully set handbrake no matter what technique or effort was used to set it.
And yet, the tables do indeed call for different numbers of handbrakes according to whether they were are set with or without airbrake assistance. Therefore, the recommendation in tables does indeed assume that handbrakes set by humans without air brake assistance will be less than fully set.
The only thing that prompts my question is the fact that the train securement tables of handbrakes required call for different numbers of handbrakes to be set depending on whether they are set with or without airbrakes applied. Some say it makes no difference whether they are set with or without air applied. If it makes no difference, why do the special instructions call for different numbers of handbrakes to be set depending on whether or not air is applied?
If you really want the hand brakes tight, a full service set isn't going to really get the brakes any tighter. (I don't know if I even agree with setting hand brakes with air set is any easier. Like Tree said, pull on it until you can't pull it any more with or without air set.) To really get a hand brake on a car tight, you need to dump the air. Put the train into emergency. Then you might be able to get them tight enough that you'll have trouble getting them to release if the pawl doesn't release.
Jeff
zugmann Euclid If it requires airbrakes being applied to get an adequate handbrake set,
Euclid If it requires airbrakes being applied to get an adequate handbrake set,
+1
Because it doesn't.
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