From the STB of Canada report:
“However, if, during a hand brake effectiveness test (when applying throttle), hand brakes are also applied on the operating locomotive(s), the retarding force from the locomotive hand brakes can give the false impression that the retarding force is that of the entire train. This can result in an inaccurate effectiveness test, increasing the risk of runaways. An LE would therefore have to compensate with a greater throttle application to overcome the retarding force of the locomotive hand brakes.”
False impressions? How can you trust a handbrake effectiveness test that is capable of giving false impressions? If you are getting a false impression, you are supposed to compensate. To do that, you would have to know that you are getting a false impression. How would you know that you are getting a false impression?
Don't apply the locomotive handbrake while performing the test?
On the MM&A, locomotive handbrakes are counted as part of the securement. So when the securement is tested, the brakes have to be applied to the locomotives.
Leaving the Independent Brake applied during the handbrake test, as occurred at Lac-Megantic, is another sure-fire way to get a false pass on the test
Greetings from Alberta
-an Articulate Malcontent
Its common on US roads to require the handbrakes be set on the engines but not the independent brake.
Dave H. Painted side goes up. My website : wnbranch.com
After thinking about this, I conclude that the TSB of Canada has made a mistake in writing the paragraph where they refer to getting “false impressions” during a handbrake effectiveness test.
I don’t see how a false impression could arise. The impression yielded by the pull test would indicate the retarding force of the entire train, contrary to what the TSB has stated. Braking force, it is determined by the friction of the brake shoe against the wheel. It is true that the locomotive wheels are directly powered by traction motors and the car wheels are not, but so what? During the pull test, all wheels are powered to turn against the brake shoe friction. The locomotive wheels are powered by the traction motors, and the car wheels are powered by the locomotives pulling the cars to turn their wheels through their contact with the rails.
While it is true that you can’t tell how much retarding force is coming from handbrakes on locomotives versus handbrakes on the cars, what difference does it make? It is only the total retarding force that matters.
I read that part as a warning that doing the test with the locomotive handbrakes applied may lead the employee doing the test to incorrectly assume the cars are secure…It may just be the way I am interpreting it
On my carrier, locomotive handbrakes are not to be used to help secure a train, only the handbrakes on the cars, for the simple reason we may, at some time during the day, need to remove the locomotives from that train for use elsewhere.
We are required by general order to apply handbrakes to cars, and then release all the brakes on the locomotive and let the weight of the locomotives try and move the cars…if it remains in place, good test, secure the locomotives and leave it, if the cars move more hand brakes should be applied, repeat as needed until train is secure.
We also do a push/pull test, if the locomotive under power has a difficult time moving the cars with only the cars handbrakes applied, it is reasonable to assume the cars are secured and can, if needed, be left unattended.
We are also required, when cutting away from cars, to “observe for a sufficient amount of time the cut of cars to be left and verify that no unintended movement occurs”
This rule allows us to cover the portion of the GCOR that refers to cars left unattended also…because the cars alone are providing the retarding force, they meet the criteria for both leaving a train unattended and a “cut of cars” unattended.
I would assume most carriers do the same thing.
Not picking a fight, but the reasoning in your last two sentences may be the major contributing factor to this event.
If the handbrakes on the cars had been sufficient to hold the entire train, including the “dead weight” of the locomotives, then nothing that was done to the locomotives afterward would have cause the train to runaway.
23 17 46 11
Ed's example (cutting the power away from the cars) notwithstanding, I don't see that there is a problem with a policy of including the handbrakes on the locomotives as part of the required number of brakes. Assuming that the locomotives will remain attached to the rest of the consist, AND that a proper securement test is done (even if it's simply releasing all brakes and observing for movement, as Ed also mentions), then the train is going to stay where it's left.
What we're really talking here is having handbrakes set on sufficient axles to hold the train. Setting brakes on a certain number of cars is only sufficient if the number of axles with brakes applied are sufficient (and the retarding force thereof is also sufficient, but that's another discussion). If eleven cars have handbrakes that apply on all four axles, that's 44 axles. If some of the cars only apply on one truck, that could be as few as 22 axles.
And I'm pretty sure that we've established that the MMA train held as long as the independent was set. If the LE had set hand brakes on ten to fifteen more axles (to cover the locomotive axles not held by handbrakes), we wouldn't be having this discussion.
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...
Ed,
I understand your points and agree with them. I don’t know how common it is to allow the inclusion of the locomotives in the count for the required number of handbrakes to be set. The report says it is the rule for the MM&A, and Dave Husman says it is common elsewhere. I am not suggesting that there is any problem with including the locomotives in the handbrake securement.
Also, just to clarify, the question that I am asking is not about the securement of the MM&A oil train. My question pertains to the general practice of including the locomotive handbrakes in the handbrake securement and the warning of false impressions that can come from that practice. The only relationship of my question to the MM&A oil train is that the information that raises the question was provided in the MM&A oil train accident report.
Also, incidentally, I don’t think that the question of the false impression even came into play in the MM&A securement because the engineer did not pull on the train to test it. He only released the automatic air brakes. He also left the independent brakes set during his test, so his test was faulty even without the false impressions.
To the question of false impressions being given by a handbrake effectiveness test that does include the locomotives, there are a couple of points that puzzle me. Say you had five engines and the rule called for 15 handbrakes. So you set the five engine handbrakes and handbrakes on ten cars. Then you pull, reasonably hard as one might assume to be prudent, and nothing moves. I would say the train is secured. I don’t see how the fact that five of the handbrakes are on engines can skew the results or lead to a false impression. If the train can’t be moved by pulling, what could amount to a false impression? When you pull on the train, all the wheels in the secured portion try to turn against the friction of the brake shoes. It makes no difference whether they are locomotive wheels or car wheels. All the wheels are powered to turn by the locomotives.
Another point that puzzles me is this. The TSB warns that a handbrake effectiveness test can give a false impression. That is a disastrous flaw in the test. The TSB says it can lead to a runaway. So what are you supposed to do about it?
The TSB says you have to pull harder. How hard? If you pull and nothing moves, what do you learn about the possibility of a false impression? You learn nothing. If the securement is capable of giving a false impression, you would have to pull hard enough to move in order to reveal that false impression. And yet if you pull hard enough to move, it might just be that you don’t have enough brakes set. So you set more brakes, and pull hard and it does not move. How do you then know you are not getting a false impression? It is a perfect Catch-22.
I do not believe there is any such possibility of a false impression that can arise from a securement that includes the locomotives. I think the TSB is wrong about that.
EuclidAnother point that puzzles me is this. The TSB warns that a handbrake effectiveness test can give a false impression. That is a disastrous flaw in the test. The TSB says it can lead to a runaway. So what are you supposed to do about it?
Setting the minimum number of handbrakes (as specified in rules and special instructions) is a good start.
The runaway problem could occur if a deep reduction was taken to stop the train. The deeper the reduction, the longer it will take to recharge the train. And until the train is recharged to a certain point, you're not going to get much from a service application (having already p****d away your air with the stop).
And this is where your runaway is going to come from.
Making an emergency application might still stop the train, if it's done before the train gets much momentum. Not depending on the independent application as part of the securement will also help a lot, even if you've set the handbrakes on the locomotives. Again, not all axles on a locomotive are secured with the handbrake, so you have those unsecured axles available for stopping power as long as the main res is above the normal operating pressure for the independent brake.
As for the false impression, if you simply do a static release (train is stopped, no force applied by the locomotive), the train may stay put. I have seen cars that were secured with a handbrake and which held in place with that brake, start to roll when bumped in the course of switching. A couple more tugs on the brake handle fixed the problem, but based on a static roll test, the car was secure.
I believe you've mentioned the issue in the past, and the reason it exists, which is what I just cited. Break that "bond" between shoe and wheel and the car will roll.
Yes, I understand what you are saying. The engineer of the MM&A oil train should not have used the independent brake to help secure the train. That was flat out wrong. There was also an issue that I did not quite follow about the locomotive handbrakes. There was a valve that would bleed off the independent brake if a handbrake were set. That valve did not work properly, so when setting the handbrake, there was actually no handbrake set. I think that may have been on just one of the locomotives. But it added one more little defect in the securement.
As to the false impression, I think the point they are making is that if you have handbrakes set on the locomotive, you get less pull out of it because the handbrakes are holding it back. And then that reduces tractive pull on the cars, leading to a false impression that the cars are being held by their handbrakes when they really are not. That is my interpretation of their point. But I think it is fuzzy logic.
Here is another way of looking at it: Say that the rules do not allow locomotive handbrakes as part of the securement. But say you decide to set them anyway just for extra assurance. And they you perform the pull test. THAT would lead to a false impression that they are talking about.
Part of the issue is that you and the TSB are talking about a "pull test". Not all railroads require a "pull test". Many railroads just require the air brakes to be released and the train not move after a certain period of time.
A bit of an apples to oranges situation.
If you are doing a pull test then yes, having any brakes on the engine would skew the results. if you are not doing a pull test then the engine handbrakes being on don't affect the outcome of the securement test.
False tests are something that happens in all varieties of human activity, from securing trains to account functions to quality control functions to any and all kinds of human activity.
It is easy to fall into the trap that you are testing something, when in reality you are just wasting time with no real test having been applied.
The MMA's LE performed a false test and believed he was doing the right thing.
Never too old to have a happy childhood!
dehusmanIf you are doing a pull test then yes, having any brakes on the engine would skew the results. if you are not doing a pull test then the engine handbrakes being on don't affect the outcome of the securement test.
Although it is not required on all railroads, it is the pull test that I am talking about; and it is also the pull test performed on a handbrake securement that includes the locomotives. That is what the TSB is referring to in this paragraph upon which I base my question:
*****
Referring to these conditions, you say that “If you are doing a pull test then yes, having any brakes on the engine would skew the results.” Skewing the results seems to be what the STB is referring to as “false impressions.” I don’t see the basis for concluding that false impressions might result.
But in the first place, considering what is at stake, why would they allow such a test if it could produce false impressions? This is especially amazing considering that there is no way to know whether the results are false impressions. This seems like an incredible flaw in the rules.
EuclidThat was flat out wrong. There was also an issue that I did not quite follow about the locomotive handbrakes. There was a valve that would bleed off the independent brake if a handbrake were set. That valve did not work properly, so when setting the handbrake, there was actually no handbrake set.
Some locomotive handbrakes operate by opening a valve and letting off the air in the brake cylinders. Not sure if the C30-7 uses this type of brake.
NorthWest EuclidThat was flat out wrong. There was also an issue that I did not quite follow about the locomotive handbrakes. There was a valve that would bleed off the independent brake if a handbrake were set. That valve did not work properly, so when setting the handbrake, there was actually no handbrake set. Some locomotive handbrakes operate by opening a valve and letting off the air in the brake cylinders. Not sure if the C30-7 uses this type of brake.
Back in the last Lac Megantic' petitnj made this comment:
"The locomotive is a different case. The air brake pushes on the bottom of brake show lever and the hand brake chain on the top. If the air brake cylinder is "out" or pressurized, the chain will tighten but loosen when the air drains out of the cylinder. (That seems like a formula for disaster -- the brakes feel tight but they are not!). "
________________
This bleed valve must be to solve this problem, but I wonder why anyone would design a brake system that way in the first place. When the pressure drained down the handbrakes were effectively released.
_____________
"A stranger's just a friend you ain't met yet." --- Dave Gardner
The valve you are discussing releases or bails off the independent brake when you tighten the handbrake…which is a good thing, as it forces you to apply enough handbrakes to hold the cars and the engine in place.
It is designed that way so you cannot rely on the independent brake to secure the train.
Theses valves often fail, as they are exposed to the elements, and most railroads whose locomotives still have them also have a general order that requires the engineer or crew to manually bail off the independent or manually trip the valve.
The intent was to force the securement of locomotives with handbrakes only, in case, as is under discussion, the engine in the locomotive is disabled and stops, thus allowing the air compressor to stop, which could result in a bleed down and runaway locomotive.
I have only seen the valve on older GEs, never seen one on an EMD.
You can reapply the independent after you tighten the handbrake by moving the brake handle
Ed, why would these valves be only on older units? Are the brakes on newer ones designed differently?
Those QRB valves were on the old EMDs as well . Search for pictures of the ATSF 5300 SD45s. Seems like the Santa Fe liked them.
The QRBs worked pretty good and they were easy to adjust. We had a special instruction on how to make sure they were set properly. They released the brake cylinder pressure on ONE cylinder.
Outstanding, I will look and see….not that we get a lot of older Santa Fe power here, but we did have a bunch of BN B30-7As here for a while, sent most of those to Brazil.
edblysardTheses valves often fail, as they are exposed to the elements, and most railroads whose locomotives still have them also have a general order that requires the engineer or crew to manually bail off the independent or manually trip the valve.
Thanks, Ed.
For others, look for or press CTRL F, (MP&E 98-11) in the PDF accessible here, (it is also page 11-57) for what the FRA says.
Here is my original question in the simplest form. It is based on the paragraph quoted from the STB of Canada in my original post. This question has nothing to with the MM&A runaway. This is just logic 101:
Say you are to secure a train on a grade and the rule calls for setting a minimum of 15 handbrakes including those on the locomotives, and then doing a pull test.
1) You set the handbrakes, release the automatic brakes, and the train does not move.
2) You pull on the train to see if it moves, and it does not move, indicating adequate securement, however, this might be a “false impression.”
3) Because you might be getting a false impression, you pull harder and the train moves, which indicates that the first pull gave a false impression.
4) You set two more handbrakes, pull as hard as before, and the train does not move.
At this point, what do you conclude? The train might be properly secured—or—you might be getting a false impression. You must rule out the possibility of a false impression that the train is adequately secured. How do you do that? There is no way to do that.
edblysard Outstanding, I will look and see….not that we get a lot of older Santa Fe power here, but we did have a bunch of BN B30-7As here for a while, sent most of those to Brazil.
Those valves were only on old 6 axle engines. On the WC we scrapped a bunch of those trucks from the Santa Fe SD45 5300 engines.
4 axle engines are all pretty much the same with truck mounted cylinders.
Euclid Here is my original question in the simplest form. It is based on the paragraph quoted from the STB of Canada in my original post. This question has nothing to with the MM&A runaway. This is just logic 101: Say you are to secure a train on a grade and the rule calls for setting a minimum of 15 handbrakes including those on the locomotives, and then doing a pull test. 1) You set the handbrakes, release the automatic brakes, and the train does not move. 2) You pull on the train to see if it moves, and it does not move, indicating adequate securement, however, this might be a “false impression.” 3) Because you might be getting a false impression, you pull harder and the train moves, which indicates that the first pull gave a false impression. 4) You set two more handbrakes, pull as hard as before, and the train does not move. At this point, what do you conclude? The train might be properly secured—or—you might be getting a false impression. You must rule out the possibility of a false impression that the train is adequately secured. How do you do that? There is no way to do that.
This depends on a quantifiable, and standardized, "pull". What's a "pull". Is it to be the application of half the weight of the locomotive, or half its tractive effort, or all of its tractive effort, or just 10k lbs of tractive effort, 0.25% of the total trailing tonnage, the equivalent of the total theoretical effective braking force of the locomotive, or just half of that....?
I really think the trailing tonnage should have a standardized application of static braking to account for problems with the motive power. After all, it was highly probably the motive power's deficit that led to the runaway. So, any future brake tests should discount the maximum retardive capacity of the locomotive.
It is a skewing of the results of the test to include the engine brakes in the test, in my inexperienced opinion.
If the engine brakes (and I said "IF") were able to absolutely lock the wheels against any rotation at all, regardless of the force applied from any source. Then consider that opening the throttle to maximum would only prove that the electric motors on the axles cannot move the engine. The rest of the train could be without brakes and all you know is that the locomotive is incapable of overcoming its own brakes. The rest of the train might be heavy, on a steep grade, on slippery rails, with a tail wind, such that it could cause the locomotive to slide on the rails and the whole train to attain a high speed.
Given that the engine's brakes may not seize the wheels completely, they are still sapping power from the locomotive in its exertion testing the brakes on the whole train and thus not really testing the holding power of the whole train against all the other forces and circumstances. I don't know how to calculate the sum of the forces and braking power in such a situation.
I conclude that in testing the brake effectiveness of the cars of a parked train, one should not have any brakes applied on the engine supplying the brake testing power.
But I think that after the test is successfully completed, the engine brakes should be applied just to hold the engine itself. I realize this may make a need to apply more brakes on the following cars than would be necessary if one were to include the Engine axles in the equation, but I see it only as added insurance to holding the train. The various methods of calculating the number of cars to have the brakes set, after lots of multiplication and division by coefficients and fudge factors, they usually include something like " Plus 1" or "Plus 10%" as an additional safety factor anyway. I think the engine brakes could be a part of that "insurance".
Semper Vaporo
Pkgs.
Class 1 rules that I am familiar with do not permit locomotive hand brakes to be used in the calculations for train securement. Tests will not be performed with locomotive brakes applied, either air or hand. After the securement test is successfully performed on the train, the locomotives will be secured by their hand brake systems.
Semper VaporoIf the engine brakes (and I said "IF") were able to absolutely lock the wheels against any rotation at all, regardless of the force applied from any source. Then consider that opening the throttle to maximum would only prove that the electric motors on the axles cannot move the engine. The rest of the train could be without brakes and all you know is that the locomotive is incapable of overcoming its own brakes.
[BaltACD, I am asking this question pertaining to the securement process that does entail setting the locomotive handbrakes and testing with them set, as the TSB refers to.]
Semper Vaporo,
I think your reasoning is correct, and I also think that it is the basis of the conclusion of the TSB regarding “false impressions.” But I do not think that conclusion is correct. Here is why:
Say you have five engines on a train where the securement calls for 15 handbrakes including the engines. You set the 15 handbrakes and pull on the train. I absolutely agree that the handbrakes on the five engines will reduce the pull that would otherwise come with any given throttle setting without the engine handbrakes set.
I also agree that this reduced pull may not extend all the way through the ten cars with handbrakes set. So you could say that the test is not testing all of the handbrakes that are set for securement. But so what? The only point of the test is to see if the train will move when pulled. And since the locomotives are part of the securement, if the locomotive handbrakes are able to hold the train all on their own when the locomotives pull against their brakes, then the train is secured.
Something else to consider: Say you had a train where the locomotives were not supposed to be part of the securement, and say that the securement called for 40 handbrakes on the cars only. After setting the 40 handbrakes, when you pull on that train, and the train does not move, how do you know that the pull extended all the way through those 40 cars? You don’t know that, and there is no need to know that. The only thing that matters is that the train does not move.
Load Securement
Thanks, Balt, for the laugh. I guess he's following the rules.
I'm still wondering-- in all the discussion about the bleed valves here, it has been specified that they are on older locomotives. Why are they not on newer locomotives? Are the brakes on newer ones designed differently?
Our community is FREE to join. To participate you must either login or register for an account.