Imagine if the technology existed where each box car had an air grabber on the top. They could use it a second main braking system (in addition to the wheel bakes), or as an emergeny stop brake system.
I would think that if such a technology could be made and perfected, trains could stop very quick. If trains could stop more aggressively then blocks could be made smaller, and trains could run faster on some blocks.
What do you think?
Im not sure I understand what your talking about… Why would it be on top? Is is something like straight air?
It sounds like he’s talking about some parachute or spoiler type device like they use on drag racers.
I would have to believe that the air resistance of such a device would be insignificant compared to the weight of the car. And it would only work up to the point where the next bridge/tunnel knocked it off.
Yes I am talking about a concept kinda similiar to what drag racers use…and from what I see…the braking capacity is tremendous…so imagine adding that to the wheel brakes trains already have.
You have to consider that the drag racer is a lightweight frame, seat, and some tires holding up a really big engine. The weight is miniscule compared to the weight of one freight car, even empty. The chute ot grabber would have to be huge and strong to have any effect.
True Tom…but imagine a few on on each car, and a train with a 100 or more cars…it all adds up. I have no idea, I’m not an aerodynamics engineers…the thought just popped in my head. [:)]
But lets face it,…wheel brakes are not all that great either. We could lock em all up if we wanted to but that would make little difference…the train would still slid on the rails a mile or so…so instread we save the metal and let it ‘ride’ to a stop its mile or so. Tractor trailer trucks are very heavy when compared to a car, and they can stop pretty quickly too. The real limit in trains, IMHO, is the amount of friction available in a metal-to-metal contact.
…that is why the signal system was implemented in the first place…cause trains can’t stop all that quickly.
Do we really need them to stop faster?
And wasnt the signal system implemented to help direct train movement??
He’s talking about this type of thing,
http://www.japantimes.co.jp/cgi-bin/getarticle.pl5?nn20050625a1.htm
the cats ears are deployed when they’re needed.
There may be more pics of the prototype on the net.
…Freight trains don’t travel that fast to make any “air diffuser” brake to work…The size would have to be enormous…and we do have those overhead space restrictions mentioned in above post. Present air applied brake shoes to the wheels are strong and effective but the design of applying them has to consider HOW they are applied and still keep the train on the tracks.
I would imagine that greater minds than ours have contemplated the possibility of doing so long before this, and for whatever reason, decided against it.
Just having “new” ideas is no guarantee that they are brilliant.
There is a perfectly fine approach to faster braking for all railroad trains, and it has been in used on streetcars and interurban cars since about 1912. It is the magnetic track brake. All PCC cars had it and so do most modern light rail cars, including New Jersey’s River Line interurban diesel light rail cars. It permits a rail car running in the street at say 40 or 45 mph to stop as fast as the automobile making an emergency stop directly ahead. The only reason it isn’t applied to regular trains is its cost, both first cost, added complexitiy and added maintenance.
All multiple unit electric trains have electric control of braking with the brake pipe an emergency backup. Most full size electric trains do not have magnetic track brakes unless they have a lot of street running. Applying this technology to freight trains would be very expensvie. But perhaps METRA should consider it as an alternative to grade separation for equipment on certain lines with problem grade crossings.
The Magnetic or Eddy current brake used in heavy rail applications runs havoc on track structure, it does more damage trhan actually help.
This would only be a speed reducer, not a true brake. Below a given speed it would be inefective reguiring two seperate and very complex systems. Most railroads are happy when the air bakes work.
Wouldn’t throwing out an anchor be just as practical![;)]
I’d hate to be on a Metra train if it had to make an emergency stop with that kind of braking system. I think they’d end of with more injuries and deaths ON the train than if they had hit a vehicle on the tracks.
…Who would pick up the anchor…Especially it they are going to one man crews…
Going on with ‘What Ifs’, what if each car had at least one truck with traction motors on it? You could change the gear ratio to where even at a low speed, a lot of electricty were generated, and you could disperse that as heat through dynamic brakes.
The actuating circuit could vary the field current on the coils inside the motor, to get a consistantly high current regardless of train speed.
The costs would still be pretty high, both initial and long term.
But for what? to keep Darwin from using rail crossings to get people? If it were well known that trains could stop very quickly, then, if nothing else changed, then I suspect that the number of people who drive around the gates would increase, along with wrongful death lawsuits.
Smaller blocks would lead to more signaling costs, though those costs could most likely pay for themselves, with higher charges for faster service.
Faster trains are still dependant on the condition of the track bed, which has been pointed out in other threads, isn’t as high on the list of things to fix as it should be.
Faster trains also themselves cost more, as fuel and maintenance costs go up.
Just some thoughts I had on this subject.
James
Air drag brakes won’t work very well at slower speeds. Drag racers usually don’t use chutes to slow down more effectively. The normal brakes do that perfectly fine. They are used to reduce the temperature spike in the rotors. The chutes just reduce the power given as heat to the brakes. It takes a hell of a lot of energy to get up to 300 MPH and just as much to slow down. The rotors used would warp if requrie to stop the care solely… Airplanes do the same thing. They use reverse thrusters built into the jet engines to reduce the load on the brakes. I’ve been on a flight where one of the engines failed and couldn’t reverse thrust for stability reasons. We had to sit in the plane for over an hour as the brake cooled form over 800 degrees Celcius. The engine that failed apparently had a bird go through it in such a way that blew a compressor blade through the side of the engine. Usually they just get chopped up real good and spat out. The probability is very low that such an incident will occur for a bird. I did thank the pilot on my way out for landing the plane in one piece. (A good landing is one you walk away from)
I’ve personally warped the rotor on my car. It was from driving during spring break. If someone gets pulled over, the cop is busy with them… Slamming on your brakes is a stupid idea. When traffic is heavier going from 70 MPH to 0 is possible. I did it 3 times in 15 minutes.
The wheels on trains used to be ribbed for your pleasure… I mean ribbed for better cooling. Dynamic braking has been able to reduce the need for that. Dynamic breaking relies on resistors to transfer heat. As long as they are cooled with the big fan properly, they will last pretty much forever. Stopping a train on a dime won’t happen. It a huge mass and all that energy must be converted to heat. Eddy brakes damage the rails or rotors as well as friction brakes if used aggresivelly. Dynamic brakes work to a limit then they would just vaporize the resistors. Any type of air brake useabe wouldn’t help
Perhaps some of the emergancy responders could help. Once that anchor gets a good hold on something, some parts of the train are going to brake rapidly.[;)]