Uniform braking is essential to my proposal and is achievable. If it can be obtained on a 11 car train of Flushing Line subway cars, it can also be obtained on a 100-car freight train, provided all cars and their loading are identacle. (Note that the people loading of the subway train is not uniform, but the slight differences do not result in the bucking and banging between cars that was typical when the IRT ran trailers as well as motors in trains, that is typical in a normal manafest freight train braking to a stop, anf that could even be heard between cars on short interuban trains, such as use of old equipment for ffan trips on the Liberty Bell Line.). Uniform braking will avoid pile-ups
I also agree that your differential braking system will reduce if not eliminate pile-ups, without uniform braking. However, it willl definitely cause stringing when derailmens occur on curves, and this can be as serious in some cases.
The cars both of you are forgetting about are the derailed cars which will NOT have a uniform or controlled deceleration.
I assume that the magnetic brakes will be attached to the trucks. Since your plan requires a deceleration rate higher than emergency (shorter stopping distance), how have you made sure the cars do not come off the trucks? All that keeps the cars on the trucks is gravity and a roughly 2" lip on the center bowl. How do you keep the momentum of the car from shoving the car off the rapidly decelerating truck?
Dave H. Painted side goes up. My website : wnbranch.com
You are correct. But one a car and a follower with a problem are a lot different than the whole train with the problem, the current case. If the couplers hold, the braking of the following cars will slow the derailed car even without trucks. If the first derailed car breaks free, without the coupler holding, than at least the following cars are braking to a stop. Assuming the situtation you describe.
In many derailments the train remains coupled, and the situation you describe does not exist, or when a break-in-two occurs, the body remains attached to the trucks, not leaving the roadbed.
Adding measures to keep the trucks in position with more than gravity is a good question.
Also note that fast braking may in some cases avoid an accident that otherwise would occur.
Dave Klepper,
I think both of our concepts are basically trying to accomplish the same goal. That is to prevent the cars behind the derailment from pushing into the derailment and forcing the derailing cars to jackknife and pile up in an accordion heap.
Both concepts depend on the train not breaking in two due to the chaos of the derailment or too much braking force on the cars behind the derailment compared to the cars ahead of the derailment. In your system, you intend that braking force to be equal. In my system, I intend it to be unequal, but not to the point where it pulls the train in two. And also not to the point where it stringlines the train on a curve.
In your system, if equal braking could maintain the distance of the zone occupied by the derailed cars at a constant length; that would keep the derailed cars in line because, if they were to jackknife, the length of that derailment zone would have to get shorter. Therefore, maintaining that zone at a constant length due to uniform braking would prevent jackknifing of the derailed cars. So I can see the point of your objective.
In my system, I also want to maintain that derailment zone length, but I also want to add a little tension to make sure it does not begin to close up during the derailment. This tension is certainly not the full extent of what would be possible if the trailing brakes were all set fully and the leading brakes were all released. Not only would that stringline any curve, but it would pull the train in two in a heartbeat.
I mentioned that my system would have a controller that would account for factors such as speed and tonnage. One other factor it would account for is location of the train on the line. This would tell it whether the train was rounding a curve or not.
Curves do limit the potential of this system because it must limit the tension on the cars ahead of the derailment in order to prevent stringlining. But even when the tension is limited somewhat, it will still offer benefit over trains without this system. Trains generally spend a lot more time on tangents than on curves. Some curves are sharper than others. So compromising somewhat for sharper curves is not a showstopper by any means. In any case, the tension must be very limited in order to prevent the train from being pulled in two. Many curves are not sharp enough to require tension to be further reduced from that amount.
In my system, if the derailment were actually occurring in a curve, the controller would not add any tension at all. It would keep both braking zones identical in braking force. Therefore, overall, I do not expect this system to ever result in stringlining a curve.
I think that both of our systems would benefit from safety chains on the trucks like those that were used on steam locomotive tenders. I have been thinking about those and suddenly realize the full operational intent of those.
CN is now charging more for older DOT-111 cars.
http://www.railwayage.com/index.php/management/cbr-cn-charging-more-for-pre-cpc-1232-tank-cars.html?channel=44
I agree with safety chains on trucks. And I agree your system would work. But the computer technology to make it work, and it may tolerate more dissimilar cars, is more complicated and the control is more complicated. Simpler to insure all cars identacle and use my simpler and more off-the-shelf components system. If a heavier car than normal does show up, simply insure it is directly behind the lead locomotives. If a lighter car does show up, simply insure it is the very last car on the train. But all cars must be equipped for the system.
blue streak 1 CN is now charging more for older DOT-111 cars. http://www.railwayage.com/index.php/management/cbr-cn-charging-more-for-pre-cpc-1232-tank-cars.html?channel=44
C&NW, CA&E, MILW, CGW and IC fan
schlimm blue streak 1 CN is now charging more for older DOT-111 cars. http://www.railwayage.com/index.php/management/cbr-cn-charging-more-for-pre-cpc-1232-tank-cars.html?channel=44 Another example of the kind of constructive changes that the some rail careerists said were impossible too costly or illegal.
Thanks to Chris / CopCarSS for my avatar.
dehusmanI assume that the magnetic brakes will be attached to the trucks.
As a very quick note: no, they would not be. They'll be conventional three-piece trucks, so very little area for the brake between the wheels, and no good place to hang them. (For the same reason tender-style locating chains would be of comparatively little value... the 'chains' would have to be applied against something like spring pressure to keep the bolster orthogonal to the underframe.)
Bolsters can easily be pinned to kingpins; it's keeping the sideframes out of skew and the bearing carriers located in the sideframes that's the main fun in a derailment. Aren't the old Car Builder's Cyclopedias full of patent devices to keep the sideframes aligned with the bolster during shocks or accident?
Skew bracing of the 'usual sort' may or may not help in a derailment. I'd be concerned that if you bent part of a skew brace, it would then act with enhanced leverage to misalign the sideframes rather than hold things steady albeit a bit whopperjobbed...
Ask Dave Klepper how long his brakeshoes are, and how wide the magnets need to be, to give effective braking on a loaded car. They sure won't be suspended from the carframe!
IF!
Never too old to have a happy childhood!
Who among us said impossible?
In fact, several people, myself included, stated outright that the shipper will likely have to pay more in fees, insurance and such and most likely will have to placard the cars as a class 2 flammable.
23 17 46 11
Posted by Norm48327
onFri, Feb 14 2014 6:52 PM
Norm,
I am moving your post over here. My idea is indeed to prevent cars from piling up in the event of a derail, as you point out. But I can’t promise that it will work every time.
That kinetic energy that you mention does have to go somewhere, but not necessarily to piling up the cars. It can be dissipated in the dragging of the derailed cars, and the braking of the cars still on the rails. Nothing has to stop on a dime. That would be impossible, as you say. Stopping a typical oil train might require ¾ mile. If one car derailed, but did not begin to tear up the track, the following cars might stay on the rails. Then that one car might drag that entire ¾ mile. It would add to the stopping power of the train, but not much.
If the first car did start tearing up track, then one car after another might derail at the same point. If it took the train ¾ mile to stop, you would have ¾ mile of tank cars dragging on the ground by the time the train stopped. The more cars that derail, the greater they will resist forward movement. If they resist too much, the cars behind might push into them and jacknife them. But if the cars ahead are pulling on the derailed cars, it will help overcome that excess resistance that would get them jacknifed by the cars behind.
But if the resistance of the derailed cars is too great, the pull of the cars ahead might break a drawbar. When that happens, the dragging resistance of the derailed cars will go way up, and the trailing cars will push into them and jacknife them if their braking cannot keep up with sudden added resistance of the derailed cars.
At this point, the system will have failed. The first of the detached derailed cars will skew and begin a jacknife process. However, by that time, the train may have slowed from 40 mph down to 20 mph. So the destructive jacknifing begins at 20 rather than at 40. That is less kinetic energy to push into the pileup. Also a factor in the mitigation is the fact that by the time the jacknifing begins at 20 mph with a sizeable number of cars on the ground, the number of cars on the rails behind the derailment has been reduced as cars have derailed. That reduction in the number of cars on the rails behind the derailment reduces the kinetic energy of those cars just as the reduction of speed does.
So, by the time the cars start to jacknife, maybe only a few of them do so before the train comes to a stop. Without this mitigation process, a derailment at 40 mph might have accordioned 30 cars into a tightly compacted heap.
So it is a balancing act with a lot of offsetting factors at play. But so is an air bag in a vehicle a balancing act. Trains have been known to derail and rerail on the fly after running on the ground for some distance. That too is a balancing act
Just ECP brakes alone would go a long way toward this mitigation effect because of their simultaneous application. Experts have cited this benefit in preventing derailments caused by UDE events. ECP brakes also produce fewer UDE events. So all I am proposing is to go just a little deeper into the basic advantage of ECP brakes, and extend it from just preventing derailments to controlling them once they begin. I am only proposing the addition of just a little bitty extra control feature that blends right into the ECP system. It is a natural extension.
I am moving your post over here.
You now have moderator privileges and can move or delete posts at will?
Norm
It may very well be that there is not room for magentic track brakes between the bottom of the regular three piece freightcar truck and the top of the rail . If the normal light rail type track brake won;'t fit, I think the resto of my proposal, electric brake control, uniform braking, and derailment detection though use of locomotive wheel-slip technology, measuring the rotation of the front and rear axles of each car and comparing the front and rear axles of each car. will be a marked improvement of the existing situation, and simpler to implement that Euclid's non-uniform approach. Note that in many cases it will stop the train faster, which may prevent a disaster in a fraction of these cases.
I did not intend to propose special track brakes for the first test train. Simply to determine what existing track brakes will do, what if any problems there are in their use in emergencies, and whether it is worhtwhile pursuing this portion of the project.
daveklepper It may very well be that there is not room for magentic track brakes between the bottom of the regular three piece freightcar truck and the top of the rail . If the normal light rail type track brake won;'t fit...
It may very well be that there is not room for magentic track brakes between the bottom of the regular three piece freightcar truck and the top of the rail . If the normal light rail type track brake won;'t fit...
The thing is that the normal type of 'transit' track brake isn't going to have the structure to 'tie into' that it would need to achieve the desired deceleration rate for a loaded car's mass.
But this brings up a slightly different potential scenario: if the magnetic brakes are not 'fully' capable of decelerating the train, they can certainly implement some degree of differential braking independent of the modulation of the air-brake system itself. And that, in and of itself, might make even a 'discontinuous' system of magnetic brakes on some of the cars a worthwhile project to consider for some circumstances...
When I looked into the idea of magnetic brakes many years ago, I assumed that they would have to be mounted on a 'sled' of some sort, running on its own small carrier or even guide wheels, and connected to the centersill of the car with some sort of linkage capable of taking the full braking moment without putting the wrong kind of thrust on the car. Now one idea of this was that if a truck were to derail, the sled (and the electromagnetic bar and 'shoe') would still largely be aligned with the rail for a perhaps significant time, during which the magnetics might tend to hold the car more 'centered' in the available clearance gage than might otherwise be the case.
(Just in case anyone misses it -- one reason I gave up on this is the derailments that would occur if any part of the 'sled' or its linkage wound up where it shouldn't be... so don't anyone start up threads on a third bold new method of arresting oil trains in their tracks... ;-} )
I think the rest of my proposal, electric brake control, uniform braking, and derailment detection though use of locomotive wheel-slip technology, measuring the rotation of the front and rear axles of each car and comparing the front and rear axles of each car...
Except that we will already have a much better derailment detector in the little RFID module glued on each sideframe end, above the bearing carrier, that is recording and transmitting shock information from wheel flats or out-of-roundness. The first sign of a derailment isn't going to be differential wheel rotation nearly as soon as it's significant shock, no? Then all you need is a small encoder on the bolster that measures absolute truck swing, and the necessary PAN-scale connectivity and small transmitter needed to signal 'derailment' to the PTC system that will ... well, modulate what braking method or other special systems are involved in stopping the train as safely as possible. Cheap, easy, ACTUALLY robust in an engineering sense... and synergistic in what it provides operating and maintenance people.
Not that I disagree with encoders on the wheelsets, but there's so much more maintenance and potential failure points/modes involved with that. If you do, I'd engrave Hall-effect-suitable 'teeth' on the wheelset rims, and let a periodic pass through retarders keep 'em faced and trued... and put the sensor carriage on the brake-shoe assembly somewhere...
edblysard In fact, several people, myself included, stated outright that the shipper will likely have to pay more in fees, insurance and such and most likely will have to placard the cars as a class 2 flammable.
This fireball crisis is more of a marketing problem for the railroads and oil industry than it is an engineering problem.
It is interesting to note that, although this problem applies to the oil industry as well as the railroads, the main media thrust focuses on the culpability of the railroads for their derailing trains. The media seems to dismiss the Bakken oil volatility and the mislabeling by the shippers.
If it were just an engineering problem, the railroads could take comfort because much of that problem is beyond their control. But since it is a marketing problem, the problem can be anything that the media says it is.
You can say that it is not a problem because the media does not know what they are talking about—that they exaggerate the danger of oil while ignoring the more dangerous materials that are shipped by rail. But it does not make any difference. If the media says the problem is oil-by-rail, then that is the problem. You can’t end the problem by disproving the media. You can’t defeat the power of the press by scoffing at it.
A Senate hearing on this rail safety problem had been scheduled for last Thursday, but was cancelled due to snow. The marketing problem will be on full display once this hearing is under way. Senators will expect the railroads to ensure the safety of people living along the rail lines because the premise of the problem is that the railroad companies are placing these people at risk for death and injury every day now with the rising oil traffic.
“Ensure the safety” does not mean that it is enough to create the probability that fewer people will be killed or injured. There is also the implication that Senators expect a very quick solution to the problem because they refer to the problem as being critical.
Against this backdrop, the industry will tell the Senators that the problem is being exaggerated; that the media is wrong; and that rail is the safest form of transportation. And then the industry will offer a purely engineering based solution to the problem that will take several years to achieve. The Senators will want to know if the industry’s solution will ensure the safety of people along the rail lines, and the industry will tell the Senators that “nothing is 100% certain.”
Ya know Bucky,
Your entire post sounds like it comes from a rail hater rather than a railfan.
Norm48327 Ya know Bucky, Your entire post sounds like it comes from a rail hater rather than a railfan.
If you're referring to the post, Euclid's, immediately above your own, I can't agree. To me, Euclid was just pointing out the rails' PR problem, no matter how faithful the rails (and shippers, and manufacturers) may be in engineering and operating for safety.
The ass's bray of the ignorant media is what gets the attention of the public and the politicians, and can't be engineered away. That's what Euclid was saying, I think.
I do agree it's a PR problem. Perhaps it's simply the way I interpreted his post. It was the last paragraph I thought was basically condemning the powers that be for paying it lip service rather than saying "We're working at correcting the problem".
And your comment on the media was appropriate.
Overmod daveklepper It may very well be that there is not room for magentic track brakes between the bottom of the regular three piece freightcar truck and the top of the rail . If the normal light rail type track brake won;'t fit... The thing is that the normal type of 'transit' track brake isn't going to have the structure to 'tie into' that it would need to achieve the desired deceleration rate for a loaded car's mass. But this brings up a slightly different potential scenario: if the magnetic brakes are not 'fully' capable of decelerating the train, they can certainly implement some degree of differential braking independent of the modulation of the air-brake system itself. And that, in and of itself, might make even a 'discontinuous' system of magnetic brakes on some of the cars a worthwhile project to consider for some circumstances... When I looked into the idea of magnetic brakes many years ago, I assumed that they would have to be mounted on a 'sled' of some sort, running on its own small carrier or even guide wheels, and connected to the centersill of the car with some sort of linkage capable of taking the full braking moment without putting the wrong kind of thrust on the car. Now one idea of this was that if a truck were to derail, the sled (and the electromagnetic bar and 'shoe') would still largely be aligned with the rail for a perhaps significant time, during which the magnetics might tend to hold the car more 'centered' in the available clearance gage than might otherwise be the case. (Just in case anyone misses it -- one reason I gave up on this is the derailments that would occur if any part of the 'sled' or its linkage wound up where it shouldn't be... so don't anyone start up threads on a third bold new method of arresting oil trains in their tracks... ;-} ) I think the rest of my proposal, electric brake control, uniform braking, and derailment detection though use of locomotive wheel-slip technology, measuring the rotation of the front and rear axles of each car and comparing the front and rear axles of each car... Except that we will already have a much better derailment detector in the little RFID module glued on each sideframe end, above the bearing carrier, that is recording and transmitting shock information from wheel flats or out-of-roundness. The first sign of a derailment isn't going to be differential wheel rotation nearly as soon as it's significant shock, no? Then all you need is a small encoder on the bolster that measures absolute truck swing, and the necessary PAN-scale connectivity and small transmitter needed to signal 'derailment' to the PTC system that will ... well, modulate what braking method or other special systems are involved in stopping the train as safely as possible. Cheap, easy, ACTUALLY robust in an engineering sense... and synergistic in what it provides operating and maintenance people. Not that I disagree with encoders on the wheelsets, but there's so much more maintenance and potential failure points/modes involved with that. If you do, I'd engrave Hall-effect-suitable 'teeth' on the wheelset rims, and let a periodic pass through retarders keep 'em faced and trued... and put the sensor carriage on the brake-shoe assembly somewhere...
My intent was mounting on the trucks because that is the only way the track brake can be aligned with the rail on all curves. Note that the side frame of the truck is outside the rail and wheels, and the track brake can be inside, rather than below, the side frame, but in line with the wheels. The Cincinnati and Lake Erie and Indiana cars, also later of course on CR&IC and LVT, had track brakes with this arrangemennt. You could barely see the bottom of them, and only when lookiing up close, but they were there and worked fine when needed. The space on the C&LE trucks is approximately the same as a typical freight-car truck.
One of the two alternators required for my derailment notification is required anyway to keep the battery charged for any electrical equipment to work and is not a maintenane item. Older dc generators were, with brushes and commutators, but not alternators with rectifiers. Sure, you can have sensors all over the place on each truck, but I think my proposal may be more cost effective and quicker to implement.
dakotafred Norm48327 Ya know Bucky, Your entire post sounds like it comes from a rail hater rather than a railfan. If you're referring to the post, Euclid's, immediately above your own, I can't agree. To me, Euclid was just pointing out the rails' PR problem, no matter how faithful the rails (and shippers, and manufacturers) may be in engineering and operating for safety. The ass's bray of the ignorant media is what gets the attention of the public and the politicians, and can't be engineered away. That's what Euclid was saying.
The ass's bray of the ignorant media is what gets the attention of the public and the politicians, and can't be engineered away. That's what Euclid was saying.
Euclid = Bucky (The poster formerly known as Bucyrus)
daveklepperOne of the two alternators required for my derailment notification is required anyway to keep the battery charged for any electrical equipment to work and is not a maintenane item. Older dc generators were, with brushes and commutators, but not alternators with rectifiers.
Would you not use a permanent-magnet rotor (in this age of cheap NdFeB) and thereby escape the need to have slip rings, either? Then you also need no external excitation (I find this is very, very, very often the failure point of exposed vehicle charging systems...)
I was under the impression that most of these trucks were drop-equalizer designs, with a 'sideframe' that remains invariant under weight transfer or other thrust conditions. My understanding is that the sideframes on three-piece trucks are always 'thick' enough that there's no way you could bolster-mount an electromagnetic brake and have it be in line with the railhead unless both offset and thin enough to go in the space under the sideframe. Where, if it breaks loose or jams, it will quickly and probably very effectively cause, rather than prevent, derailments. The same is very likely true of a brake suspended directly under the sideframe, say from the attach points for skew braces.
I wonder if it is possible to make the brake 'wide' laterally, perhaps with multiple sets of windings, and use a (rather simple!) sensing method to actuate only the parts of the brake that 'magnetically couple' to something underneath, regardless of how far displaced from 'centerline' of the magnetic brake you get on curves (or other conditions, named or expectable). How far out could the structure project before it starts being a bane to crewpeople walking a train 'on the road' with restricted walkway access in the dark?
Since it would be highly beneficial to prevent the derailed trucks from pivoting on their center bearings after derailing, I have thought about truck safety chains for this safe train concept. However, up until about now, I have never completely understood the theory behind truck safety chains. They were once common on passenger car trucks and nearly universal on steam locomotive tender trucks.
But what I never understood is this: Since the chains need considerable slack to allow the trucks to pivot in normal operation, a derailed truck would also be allowed that amount of pivot which might be perhaps 30 degrees to the line of track. Yet, if a derailed truck were allowed that much pivot, it would be very likely to quickly twist to that limit upon derailment. That much pivot on the derailed truck would cause enormous skew stress and probably cause the truck to break its center pin and disengage its center bearing from the car bolster; despite the presence of safety chains.
But what I now realize is that preventing that truck separation is not the point of safety chains. They cannot be loose enough to permit operational pivot and yet be tight enough to prevent separation from twisting during a derailment.
So it is a forgone conclusion that the truck will separate upon derailment even with safety chains. But the safety chains come into play after the truck separates. When the truck separates, it drops back until the two leading direction chains tighten. Then upon tightening, those two chains force the truck to straighten back out to run in line with the track. It will be running offset to the rear of the normal position by about a foot or so; and it may hunt side to side somewhat; but the two chains will tend to re-center it side to side, and keep it tracking in line with the track.
Ken, that's cold. That's REALLY cold!
EuclidYou can say that it is not a problem because the media does not know what they are talking about—that they exaggerate the danger of oil while ignoring the more dangerous materials that are shipped by rail. But it does not make any difference. If the media says the problem is oil-by-rail, then that is the problem. You can’t end the problem by disproving the media. You can’t defeat the power of the press by scoffing at it.
Historical perspective (not media):
The NTSB was already saying the DOT 111s were unsafe in accident reports in the 1990s (as early as 1991). NTSB/SS-91/01 questioned "the safety of 111A tank cars. It determined that this classification of tank car has a high incidence of tank integrity failure when involved in accidents and that certain hazardous materials are transported in these tank cars even though better protected cars (less liable to release the transported product when involved in accidents) are available."
Why has it taken 23 years to address this issue? Perhaps not solely railroad responsibility, but in 1991 there was no Bakken crude. All of this sounds like blame some other agency or industry and meanwhile nothing was done in spite of strong evidence of the hazard. That is negligence.https://archive.org/details/ensuringrailroad003725mbp
Overmod Would you not use a permanent-magnet rotor (in this age of cheap NdFeB) and thereby escape the need to have slip rings, either? Then you also need no external excitation (I find this is very, very, very often the failure point of exposed vehicle charging systems...)
A permag rotor sound likes a good idea to me, though the devil would be in the details of where the alternator is mounted. What would make a bit more sense to me is an "energy harvesting" style of generator, perhaps nestled in the spring box of the truck to keep a battery or supercap charged. I would guess that the braking effort would only need to last for a few seconds. Designing the electromagnet coil for short term operation will also cut the amount of conductor needed.
I was under the impression that most of these trucks were drop-equalizer designs, with a 'sideframe' that remains invariant under weight transfer or other thrust conditions. My understanding is that the sideframes on three-piece trucks are always 'thick' enough that there's no way you could bolster-mount an electromagnetic brake and have it be in line with the railhead unless both offset and thin enough to go in the space under the sideframe. Where, if it breaks loose or jams, it will quickly and probably very effectively cause, rather than prevent, derailments. The same is very likely true of a brake suspended directly under the sideframe, say from the attach points for skew braces. I wonder if it is possible to make the brake 'wide' laterally, perhaps with multiple sets of windings, and use a (rather simple!) sensing method to actuate only the parts of the brake that 'magnetically couple' to something underneath, regardless of how far displaced from 'centerline' of the magnetic brake you get on curves (or other conditions, named or expectable). How far out could the structure project before it starts being a bane to crewpeople walking a train 'on the road' with restricted walkway access in the dark?
The C&LE cars used an archbar truck and relatively small wheel diameter, so the magnetic track brakes could not have taken up too much space. As Dave said, the electromagnet needs to be in close alignment with the rail as the induced field and resulting mechanical force are inversely proportional to the air gap.
I'd also want some evidence that the brake would prevent more accidents than it would cause.
- Erik
I am trying to avoic Buck Rogers stuff. Rotating magnet alternaters would be just fine, but alternators using slip rings are already available in small packages. Again, with uniform braking, I cannot imagine magnetic track brake making things worse. I do believe the concept should be tested first with a prototype car or pair of cars, then with a 50 or 100 car train. The question is: Is the shorter stopping distance worth the extra complexity of the trucks and control system? The derailment singalling features of the alternators would be preserved with a rotating magnet alternator design, and if such equipment is available in the small size required, that would be preferable of slip rings, I agree. But energy recovery from spring bounce etc looses completely the derailment detection function, which is equally important. I do not know whether the alternator on the outer axle of each truck should be built into the wheel bearing, be belt driven, grear driven, or even integral with the wheel, as in Magnet Motor's bus and tram motors (Germany), also a frim that make wheel motors in Derby, England (Stored Energy Systems, Ltd.?), and has a good businss in "Rail Cats" for moving lightweight railcars in yards and shops..
In summary: The two alternator wheel rotation comparison system for derailment detection is a robust system using existing technology and only slightly modified existing equipment.
Uniform braking with uniform cars is essential for the fastest possible safe braking in any event and requires electric control.
There has never been a case in railway history where magnetic track brakes have made any situation worse, and if braking is utiform with uniform equipment, I consider the idea of it making things worse with these brakes as not reasonable. But the question remains whether the shorter shopping distance obtained is worth the added complexity. Each magnetic brake mechanism woujld be screwed tightly to the sideframe below the bolster, to avoid varying distance between mechanism and rail, as they were on the C&LE cars, and are on those preserved.
The amount of added rolling resistance added by the alternator will be trivial, and almost non-existant when the battery is charged and the train running with brakes released. Head-end power can also be accomodated, and then each car's battery is there primarily for break-in-two emergencies only.
erikemAs Dave said, the electromagnet needs to be in close alignment with the rail as the induced field and resulting mechanical force are inversely proportional to the air gap.
What I think Dave has been advocating is the kind of track brake that is suspended by springs, so that when it is activated it 'clamps' electromagnetically down on the railhead. It is faced with material that optimizes friction but also provide minimal wear, 'welding' transfer of shoe material, etc. The braking action is a combination of induced eddy current and straight friction from the clamping between the brake magnet(s) and the steel reilhead.
If his design is similar to what mine was, the 'contact shoe' is somewhat reminiscent of the old 'diamond' composition shoe from the late 1800s (whatever it was called) in that part of the contact area is optimized for friction, and the rest is optimized to carry the magnetic lines of force. So when the brake and shoe are applied, the magnetic field can be taken up as near saturation as possible, without any air gap other than that induced by things like surface-wear mismatch or ablation from the friction material. (I had several versions in which the shoe was made similar to a patterned magnetic clutch, with all the elements separately able to move vertically in a carrying frame, so that independent modulation of the electromagnets and the effective field strength through the magnetic circuit could be done independently.)
Now would be a good time to mention that the 'ideal' place to implement this type of brake is on low-frame or well cars, where the underframe structure itself is close enough to the railhead that the track brake can be carried on the car frame completely independent of the trucks. My system was intended primarily for the same sort of purpose as the hydrokinetic brake on the British APT-E -- very prompt and positive deceleration from comparatively high speed down to 'normal' braking speeds -- without requiring large amounts of energy to be transferred through the small contact patches between wheel and rail, or causing changes to wheel geometry as a consequence of high brake wear. (This was back in the days when everybody 'knew' a train could not be driven above roughly 310 mph with motored wheelsets, because no further energy could be transferred through adhesive contact of wheel and rail for acceleration... and the 'smart action' was on LIMs or similar noncontact propulsion to also provide the high-speed, and even some of the low-speed, braking without compromising either sensitive suspension movement or sensitive wheel structure and tread-profile integrity).
I think I specifically rejected the idea that you could harvest suspension energy to charge the system (on oil trains), in very large part because neither extended nor particularly long range of motion is achievable in a three-piece truck system that has a large ride-height disparity between loaded and empty.
Meanwhile... are not belt- or Spicer-driven generators about to be illegal on passenger cars? And I would sooner stick my hand in a cobra's mouth than say I was going to integrate part of the alternator into the wheelset, or attach it to the wheelset in a way that covers some of the wheel so it can't be immediately inspected for cracks or other incipient damage...
(I'd think the best place to put the alternator -- provided you can make it small enough, and well-enough encapsulated from harsh environment -- would be outboard of the roller-bearing endcap, driven by something like a splined plate clamped by the roller-bearing cap endbolts, and held by a full elastomer mount in a bracket attached to the sideframe, arranged so that if the alternator seizes for any reason it will not impair wheelset rotation. This should incidentally greatly simplify how the connections from the 'generator' to the rest of the car can be made, and is of course as accessible as any alternative, and drop-dead simple to apply to almost any truck or wheelset...)
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