Answering a private communication: By the time I got to them, the Baltimore and Philadelpia Brilliners (City System, not cars 1 - 10 on Red Arrow) had identacle track brakes and motors used for dynamic braking, of course) that the St. Louis and Pullman PCC cars had. But this may not be the original equipment on these cars. There were differences in the control system, butg not as great as the Boston GE-Pullman "Picture Window" PCC cars, which reverted to the older cam-control system and were air-electric, not all-electric. I never did get to the "Miss America Fleet" in Atlantic City before buses took over, so I cannot speak about the only Brilliner success, but they were air-electric, not all-electric. Incidentally, the Atlantic City streetcar system was a PRR subisdiary, and the Brilliners and older cars had PRR classication letters and numbers!
You have a right to be proud of your son, and yes, I am a veteran.
The DART LRT's actually have a combined braking. They have track brakes and dynamic brakes. The operator can not choice which one he wants. If he is braking then the train is using both track and dynamic brakes.
The only time both are not used is when the train is put into emergency. The dynamic is cut out automatically at that time.
The Cleveland RTA Rapid Transit Shaker Trains use a track braking system where the brake pads hit the tracks rather then the wheels. The claim is that it reduces wear on the wheels.
I am also sure that most LRT and subways use retro-gen braking already.
Conversion of the entire N. A. freightcar fleet to electrically-controlled air-brakes IS possible. The system would be set-up with each car having a reliable microprossessor with reduncancy. If all cars on a freight train were set up for electric braking, the conventional locomotive brake-stand would control varying frequencies to determine the brake setup on each car via the electrical train line. But if no electrical train line with a constant rest signal was present, the brakes would operate conventionally through reduction and recharging of air train line air pressure. The electric brake feature would operate only if all cars were so equipped or if just a few air-only cars were attached to the rear with brakes deactivated (not on a mountain division, obviously).
Concerning Presidents Conference Commission (PCC) cars. Most had air brakes for the final stop and holding, a mechanical parking brake, the dynamic brakes using the motors for most of the braking effort from speed, and magnetic track brakes for emergency stops. I the post-WWII period, most, but not all, were "all electric", with dynamic brkaing extended into lower speeds, parking and final braking combined into one mechanical brake, and the magnetic track brake retained. As far as I know, the first all-electric cars and the first with magnetic track brakes were the 1912 center-door West Penn interurban cars wherein the final braking was by a conventional brute force handbrake. On those cars, magnetic track brakes got their power from them motors serving as generators, sort of a cross between regenerative and dynamic braking, and were used for service as well as emergency applications.
Both air electric and all electric PCC's were available as mu cars with electrical control between cars.
.....Peter: I'm sure retarder use is becoming common now and has been for a while. Our experimenting with them I mentioned in an above post was 40 - 45 years ago. Did it in the Pennsylvania and Arizonia mountains. Our trucks had automatic trans. too {Also experimental}, during the tests....Semi size and smaller 26,000 GVW. Smaller size was targeted for units such as school buses, wreck trucks, emergency vehicles....and all sorts of uses within that size.
Quentin
phbrown wrote: jchnhtfd wrote: However, electrically operated brakes, in which an electrical signal operates the conventional air brakes, are definetly on their way. Passenger equipment in some areas already has them. In freight operation, it's a bit difficult, as every car in a consist has to have them (otherwise, you could get some pretty horrible in-train draught and buffer forces) which will limit them to unit trains for a while -- probably quite a while. The stopping difference is significant, but it's also a lot easier for the engineer to control the train in general. One might note that the regular air brakes would still work in the regular way as a back up.Seems to me that using wireless, rather than wired, communication could perhaps go a long way to get rid of that requirement that every car has to be equipped with the electrically-controlled brakes. Radio reception is naturally a problem, but if it can be solved for EOT's, it's not insurmountable for wireless communication among cars. It's not clear to me why the in-train forces are worse with brakes being applied from several locations in a train than with brakes being applied from front and rear (as currently with EOT's). Could you explain that further?Peace,--Peter
jchnhtfd wrote: However, electrically operated brakes, in which an electrical signal operates the conventional air brakes, are definetly on their way. Passenger equipment in some areas already has them. In freight operation, it's a bit difficult, as every car in a consist has to have them (otherwise, you could get some pretty horrible in-train draught and buffer forces) which will limit them to unit trains for a while -- probably quite a while. The stopping difference is significant, but it's also a lot easier for the engineer to control the train in general. One might note that the regular air brakes would still work in the regular way as a back up.
However, electrically operated brakes, in which an electrical signal operates the conventional air brakes, are definetly on their way. Passenger equipment in some areas already has them. In freight operation, it's a bit difficult, as every car in a consist has to have them (otherwise, you could get some pretty horrible in-train draught and buffer forces) which will limit them to unit trains for a while -- probably quite a while. The stopping difference is significant, but it's also a lot easier for the engineer to control the train in general. One might note that the regular air brakes would still work in the regular way as a back up.
Seems to me that using wireless, rather than wired, communication could perhaps go a long way to get rid of that requirement that every car has to be equipped with the electrically-controlled brakes. Radio reception is naturally a problem, but if it can be solved for EOT's, it's not insurmountable for wireless communication among cars.
It's not clear to me why the in-train forces are worse with brakes being applied from several locations in a train than with brakes being applied from front and rear (as currently with EOT's). Could you explain that further?
Peace,
--Peter
Well, let's see here... first off, wireless problems have not been solved for EOTs or mid-train units; they all have a default mode which allows them to coast for a bit until communication picks up again. Which happens quite often in mountainous territory, which is exactly where you need reliable brakes!
The problem with in-train draft forces exists with EOT applied brakes, too, and must be taken into account by the engineer. It's usually not too bad. The problem I envision (and maybe I'm creating too much of a thing) is a fast applying electric or wireless brake on a couple of light cars -- say empty tanks -- ahead of a dozen heavy conventional cars (say hoppers). I can't think that the results would be pretty... In the present setup, you do have considerable tension in the back end of the train (not a problem usually) and some slack take up in the front, but no odd action in the middle.
As a comment to some of the posts on retarders: they are very common on large trucks and some busses. They have to be used with caution, as it is quite possible to jack knife your rig on wet or slippery pavement with them (been there, done that, didn't like it much).
Several series of PCC streetcars and rapid transit cars were all-electric and did not use air to activate the brakes. I believe that all of CTA's current rapid transit fleet is so equipped.
jchnhtfd wrote:However, electrically operated brakes, in which an electrical signal operates the conventional air brakes, are definetly on their way. Passenger equipment in some areas already has them. In freight operation, it's a bit difficult, as every car in a consist has to have them (otherwise, you could get some pretty horrible in-train draught and buffer forces) which will limit them to unit trains for a while -- probably quite a while. The stopping difference is significant, but it's also a lot easier for the engineer to control the train in general. One might note that the regular air brakes would still work in the regular way as a back up.
Jock,
I'm a Clerk with NJ Transit RR. All of our newer equipt. and newly rehabbed equipt. have
"Dynamic Braking" which is , I think, what you're referring to. This occurs when the the
circuitry in the traction motors is reversed to turn the motors into generators. This in turn
creates a load on the main traction (propulsion) generator, causing a braking action. This
is similar to the action of "jake brakes" (Jacobs Engine Brakes) on heavy trucks.
Hope this helps.
Jim Swank
NJ Transit RR.
http://www.telma.com/en/index.php
With these we could save millions in have to replace and dispose of railroad car break pads a year not to mention labor savings of car inspectors
Jock Ellis Cumming, GA US of A Georgia Association of Railroad Passengers
jockellis wrote:...virtually no more brake work ever worth the extra cost and weight?
I have yet to see a mechanial system which elimanates maintenance requirements...typically, you are exchanging a low tech, mechanical system for a high tech, electro-mechanical system which requires a different skill set to trouble shoot and repair...more training, more specialized equipment...
It may reduce, but I doubt it would eliminate, brake work.
And, typically, the dynamic type brakeing is less effective as the speed decreases...and it need power to work at all, so when you want to come to a complete stop or cut out a car and park it at a siding, you are still going to need your friction brake...
....Additional braking....or retarding is not a recent thought....Our company {a major one}, in the automotive field experimented with retarding the drive train 45 or so years ago.
Ours was a design that was hydraulic in concept.....Parts running in a space with min. clearance and filled with pressurized oil when retarding was required on a down hill run. We did our experimental runs and testing in Arizona and Pennsylvania. It never went into production but it did do the job of holding a load at a certain speed on a downgrade....Tremendous heat would build but using a heat exchanger took care of the heat build up as the bottom of the grade was attained. It really did a good job....Perhaps just a bit ahead of it's time. Experiment was with truck power trains.
samfp1943 wrote: jockellis wrote:G'day, Y'all,An auto mechanic today was telling me about electric retarder brakes currently on our city's newer firetrucks and the trend of the future in automotive braking. Will such brakes, which I understand are like an electric motor, be used in trains? I could be more specific about this, but I don't know what I'm talking about.Jock: What you are referring to are brake retarders and driveline retarders, not too common in this country, but long used in Europe; inter-city buses and long haul trucks use them pretty heavily over there. The use of these components did increase the weight of the user vehicle, but they were waived by various countries which would allow the added weight to the vehicle without a penalty, because of the safety benefit. Retarders can be electro-mechanical, as well as hydraulicly operated. They are used in applications where much braking and stopping are requiered, such as garbage trucks [ waste collection, or fire apparatus. Mostly on larger trucks rather than lighter, smaller vehicles. A couple of manufacturers/suppliers are Bendix and Telma, of France.. Search truck retarders,or brake retarders for more info. Hope this helps.
jockellis wrote:G'day, Y'all,An auto mechanic today was telling me about electric retarder brakes currently on our city's newer firetrucks and the trend of the future in automotive braking. Will such brakes, which I understand are like an electric motor, be used in trains? I could be more specific about this, but I don't know what I'm talking about.
Jock:
What you are referring to are brake retarders and driveline retarders, not too common in this country, but long used in Europe; inter-city buses and long haul trucks use them pretty heavily over there. The use of these components did increase the weight of the user vehicle, but they were waived by various countries which would allow the added weight to the vehicle without a penalty, because of the safety benefit.
Retarders can be electro-mechanical, as well as hydraulicly operated. They are used in applications where much braking and stopping are requiered, such as garbage trucks [ waste collection, or fire apparatus. Mostly on larger trucks rather than lighter, smaller vehicles. A couple of manufacturers/suppliers are Bendix and Telma, of France.. Search truck retarders,or brake retarders for more info. Hope this helps.
Not sure about other parts of the US, but all of the transit buses here in Dallas have the retarders on them. Most of the 18 wheelers also have the retarderes, but not called retarders they call them an engine brake.
Can't really be applied to trains but, as samfp1943 says, pretty much a standard on European buses.
The electric retarders on trucks etc. sound to me like dynamic brakes on engines, and they've been used for years. They are beginning to be used, in a somewhat different way, on road vehicles: the 'hybrid' cars and trucks coming out use their electric boost motors to recharge their batteries when they are slowing down. Given intelligent drivers, the mechanical brake life can be tripled and the fuel mileage improved as much as 20 to 30 percent.
Regenerative or electric brakes on each car would be a maintenance nightmare; I don't see that happening. However, electrically operated brakes, in which an electrical signal operates the conventional air brakes, are definetly on their way. Passenger equipment in some areas already has them. In freight operation, it's a bit difficult, as every car in a consist has to have them (otherwise, you could get some pretty horrible in-train draught and buffer forces) which will limit them to unit trains for a while -- probably quite a while. The stopping difference is significant, but it's also a lot easier for the engineer to control the train in general. One might note that the regular air brakes would still work in the regular way as a back up.
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