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Model Forum / General / Railroads / July 2006DCC and running locos from overhead traction wiring
Hi, I've got a couple of loco models that have live overhead traction wiring support through their pantographs and one question which I've raised in forums at my site in these two threads: http://www.railzone.org/phpBB2/viewtopic.php?t=101 http://www.railzone.org/phpBB2/viewtopic.php?t=30 is whether there is any standard for whether the left-hand or the right-hand rail is connected to the pantograph(s) for power collection using DCC. I haven't come across a standard for this, but someone who's more savvy with the NMRA standards may well know what the answer is. Failing that, I will ask the folks on the NMRA DCC working group list since I'm still a member of that list. With the Modelling the Railways of NSW convention coming up, I'm hoping to fathom out what's going on with electric loco and passenger train models. I still have one of Ian Storrie's excellent 86 class kits (unfinished), but wouldn't it be fantastic to have high-quality brass models of the 85 and 86 class NSW electric locos, and perhaps even of the Victorian E-class locos, since that's an ideal medium for modelling electric locomotives in HO scale. Thanks if you can provide a definitive answer to the question. Feel free to comment in the forums at my site too if you'd like to. I'll transfer any information from here to there otherwise. Regards, Craig.  SignatureCraig Dewick - Professional Train Manager (RailCorp) + HO Scale Rail Modeller http://www.railzone.org -- Galleries, Forums, Links, Data, etc.! Send email to craigd@lios.apana.org.au -- RailCorp Train Crew Council: http://www.rctcc.org Oz Rail Safety List: http://lios.apana.org.au/mailman/listinfo/aus_rail_safety > Hi, > [quoted text clipped - 11 lines] > I haven't come across a standard for this, but someone who's more savvy with > the NMRA standards may well know what the answer is. Craig http://www.nmra.org/standards/s-5.html Section 4 provides the answer. In a nutshell appying positive voltage to the overhead should make the model go forward. The negative would be the left hand running rail, as per normal 2 rail practice. A switch (if fitted) would switch the positive connections between RH rail & overhead. Any DCC changes would have to reflect this. SignatureRegards Kevin Martin To reply - delete what is "not required" (Abbrev) from my address. >http://www.nmra.org/standards/s-5.html >Section 4 provides the answer. In a nutshell appying positive voltage to >the overhead should make the model go forward. The negative would be the >left hand running rail, as per normal 2 rail practice. A switch (if >fitted) would switch the positive connections between RH rail & overhead. >Any DCC changes would have to reflect this. Thanks for the info. It doesn't really help much with DCC since there is no such thing as a 'positive voltage' and 'negative voltage' with DCC. It's a pulse-width modulated square wave with an amplitude of between 15 and 20 volts. It could be something that's much more difficult to solve in reality because if the pantographs are connection to one specific power pickup side of the loco, changing direction would require either a shift in 'polarity' of the power feed to the overhead wiring or a device in the loco itself to change which side of the power pick-ups it is connected to. Does that make sense? I'm not sure if it does to me but maybe this is something that's been largely ignored in terms of DCC development. Craig. SignatureCraig Dewick - Professional Train Manager (RailCorp) + HO Scale Rail Modeller http://www.railzone.org -- Galleries, Forums, Links, Data, etc.! Send email to craigd@lios.apana.org.au -- RailCorp Train Crew Council: http://www.rctcc.org Oz Rail Safety List: http://lios.apana.org.au/mailman/listinfo/aus_rail_safety > Thanks for the info. It doesn't really help much with DCC since there is no > such thing as a 'positive voltage' and 'negative voltage' with DCC. It's a [quoted text clipped - 8 lines] > I'm not sure if it does to me but maybe this is something that's been > largely ignored in terms of DCC development. Not really, I can't see why DCC is any different WRT pantographs/pickups. Just liven the overhead so that it is equilavent to the RH rail. If you turn it around you might have an issue though, I haven't thought too much about that. SignatureRegards Kevin Martin To reply - delete what is "not required" (Abbrev) from my address. > Thanks for the info. It doesn't really help much with DCC since there is no > such thing as a 'positive voltage' and 'negative voltage' with DCC. It's a > pulse-width modulated square wave with an amplitude of between 15 and 20 > volts. What scale are you modeling? DCC on my HO club's layout is 14VAC at the booster (with the Digitrax Chief system) with a RMS meter, Tony's RRamp meter. And on my home HO layout, it's more like 12VAC (with my Digitrax Zephyr system). > It could be something that's much more difficult to solve in reality because > if the pantographs are connection to one specific power pickup side of the [quoted text clipped - 3 lines] > I'm not sure if it does to me but maybe this is something that's been > largely ignored in terms of DCC development. To do that so the power pick up doesn't matter, the solution is simple... Wire both rails to the same polarity and use the catenary for the other polarity, just like the prototype. It's what my old club did for 45 years on our trolley trackage, and it worked very well, considering it was live overhead. It also meant that we never had to isolate diamonds and rail frogs. Paul A. Cutler III ************* Weather Or No Go New Haven ************* > What scale are you modeling? DCC on my HO club's layout is 14VAC at the > booster (with the Digitrax Chief system) with a RMS meter, Tony's RRamp > meter. And on my home HO layout, it's more like 12VAC (with my Digitrax > Zephyr system). Yes, but the DCC system runs with square wave and not sine wave current. > To do that so the power pick up doesn't matter, the solution is > simple... Wire both rails to the same polarity and use the catenary for the > other polarity, just like the prototype. Correct - until you want to run a diesel/steam loco... Klaus SignatureModelbane Europas hjemmeside: http://www.modelbaneeuropa.hadsten.dk Modeltog, internet, gratis spambekæmpelse, elektronik og andet: http://home6.inet.tele.dk/moppe Turbogrilstarter: http://home6.inet.tele.dk/moppe/tgs.html According to Lenz (who developed DCC), several more European modelers, and myself, the reason not to run with live overhead is fairly simple and has been referred to indirectly in some of the answers. The small contact area of the pan/wiper as compared to the contact points of the wheels. Also, in our experience, more arcing takes place with pans and pantograph wipers which the highly sensitive control unit interprets as a short and then shuts down. Unless your layout will receive fairly heavy use to keep the overhead wire clean and arc free, I would suggest running normal rail to rail. It can be done, as I have done it (European prototype), however, it was found that the rail to rail solution was more reliable. Signature+GF+ SURGEON GENERAL'S WARNING: Books may introduce unfamiliar or confusing ideas. In the event of uncomfortable self-reflection, heat to 451° Fahrenheit ( 232.78° Centigrade or 505.9 Kelvin ) and seek television immediately. www.internationalrailfair.com www.ete.org > Yes, but the DCC system runs with square wave and not sine wave current. Ok...but I have to tell you that our transformers powering our boosters are using the 14VAC taps. Are you saying that the voltage is higher than that after it goes through the booster? > > To do that so the power pick up doesn't matter, the solution is > > simple... Wire both rails to the same polarity and use the catenary for the > > other polarity, just like the prototype. > > Correct - until you want to run a diesel/steam loco... You could simply use a toggle to switch between the two (live overhead vs. normal 2-rail)...unless you want to run diesels/steam with the electrics. Was that common in Austrailia? Paul A. Cutler III ************* Weather Or No Go New Haven ************* > Ok...but I have to tell you that our transformers powering our boosters > are using the 14VAC taps. Are you saying that the voltage is higher than > that after it goes through the booster? 14 volts AC becomes 18VDC when it is rectified. After that is is beeing chopped into squares. > Was that common in Austrailia? I don't have a clue. But I can tell you that here in Denmark a lot of diesels rund undeneath overhead wire..... Klaus SignatureModelbane Europas hjemmeside: http://www.modelbaneeuropa.hadsten.dk Modeltog, internet, gratis spambekæmpelse, elektronik og andet: http://home6.inet.tele.dk/moppe Turbogrilstarter: http://home6.inet.tele.dk/moppe/tgs.html >> Ok...but I have to tell you that our transformers powering our boosters >> are using the 14VAC taps. Are you saying that the voltage is higher than >> that after it goes through the booster? >14 volts AC becomes 18VDC when it is rectified. And regulated properly. >After that is is beeing chopped into squares. Sort of, but the duty cycle isn't fixed. It's a variable duty cycle signal. The timing of the voltage transitions is what conveys data to the decoders. >> Was that common in Austrailia? >I don't have a clue. But I can tell you that here in Denmark a lot of >diesels rund undeneath overhead wire..... Same here. There are almost no electric locos now. Only about 4 are insured for live use but they're owned by a freight company (Silverton) which is partly-owned by the chairman of Pacific National and that company only runs diesel locos. We've got many electric suburban and intercity passenger trains at CityRail running off the 1500 VDC overhead traction system system. The 46, 85 and 86 class electric locos ran off that as well. I was a trainee driver at Enfield in the early 1990's when all three classes of electric loco were still being used. I was rostered for the electric locomotive school the same week I had a call about transferring from freight over to CityRail in late 1994. 8-) Craig. SignatureCraig Dewick - Professional Train Manager (RailCorp) + HO Scale Rail Modeller http://www.railzone.org -- Galleries, Forums, Links, Data, etc.! Send email to craigd@lios.apana.org.au -- RailCorp Train Crew Council: http://www.rctcc.org Oz Rail Safety List: http://lios.apana.org.au/mailman/listinfo/aus_rail_safety > And regulated properly. Not allways. My Roco "lokmaus" just makes DC from the AC and chops is into squares. > Sort of, but the duty cycle isn't fixed. It's a variable duty cycle signal. > The timing of the voltage transitions is what conveys data to the decoders. It is a powerfull serial data transmission :-) > Same here. There are almost no electric locos now. Only some lines i Denmark is electrified, so mainly all traffic is done by diesel. Except for transit trains between Swenden and Germany and a lot of local traffic on Sjælland (a large island, containing Copenhagen) Klaus SignatureModelbane Europas hjemmeside: http://www.modelbaneeuropa.hadsten.dk Modeltog, internet, gratis spambekæmpelse, elektronik og andet: http://home6.inet.tele.dk/moppe Turbogrilstarter: http://home6.inet.tele.dk/moppe/tgs.html > > Ok...but I have to tell you that our transformers powering our boosters > > are using the 14VAC taps. Are you saying that the voltage is higher than [quoted text clipped - 3 lines] > > After that is is beeing chopped into squares. I have to disagree with that. For starters, DCC is only rectified in the loco's decoder. After it comes from the transformer and goes through the booster, it's still AC. Digital square wave, but still AC. Secondly, I recently had to test exactly how much DC volatage was produced by a Digitrax DH123 decoder for a semaphore signal installation I was doing. Using our 14VAC booster and a Digitrax Chief for a "brain", my DH123 produced approx. 12.5VDC to the motor leads... So I don't know where you are getting 18VDC from. > > Was that common in Austrailia? > > I don't have a clue. But I can tell you that here in Denmark a lot of > diesels rund undeneath overhead wire..... It's also very common east of New Haven, CT today on the NEC. Connecticut runs diesel powered commuter trains called "Shore Line East" to Old Saybrook, and the MBTA runs diesel commuter trains between Providence, RI and Boston, MA...all under the wire. Historically, however, it was more the exception than the rule. Paul A. Cutler III ************* Weather Or No Go New Haven ************* > I have to disagree with that. For starters, DCC is only rectified in > the loco's decoder. You just vrote that you had a 14VAC transformer. If you rectify that voltage (and you do that inside the booster) you get 18 volts DC. This voltage is chopped into squares by the booster. Have you ever seen a circuit diagram of a bosster, or even looked at the components inside a booster ? (been there done that - got the t-shirt) Klaus SignatureModelbane Europas hjemmeside: http://www.modelbaneeuropa.hadsten.dk Modeltog, internet, gratis spambekæmpelse, elektronik og andet: http://home6.inet.tele.dk/moppe Turbogrilstarter: http://home6.inet.tele.dk/moppe/tgs.html Klaus D. Mikkelsen spake thus: >> I have to disagree with that. For starters, DCC is only rectified in >>the loco's decoder. > > You just vrote that you had a 14VAC transformer. If you rectify that > voltage (and you do that inside the booster) you get 18 volts DC. This > voltage is chopped into squares by the booster. OK, OK: "chopped into squares" = converted to AC. The DCC signal is AC, just a square wave instead of a sine wave. Still AC. SignatureAny system of knowledge that is capable of listing films in order of use of the word "f.ck" is incapable of writing a good summary and analysis of the Philippine-American War. And vice-versa. This is an inviolable rule. - Matthew White, referring to Wikipedia on his WikiWatch site (http://users.erols.com/mwhite28/wikiwoo.htm) > OK, OK: "chopped into squares" = converted to AC. The DCC signal is AC, > just a square wave instead of a sine wave. Still AC. You can call it AC. If you call datatransmission on a RS485 network for AC too. Klaus SignatureModelbane Europas hjemmeside: http://www.modelbaneeuropa.hadsten.dk Modeltog, internet, gratis spambekæmpelse, elektronik og andet: http://home6.inet.tele.dk/moppe Turbogrilstarter: http://home6.inet.tele.dk/moppe/tgs.html > > OK, OK: "chopped into squares" = converted to AC. The DCC signal is AC, > > just a square wave instead of a sine wave. Still AC. > > You can call it AC. If you call datatransmission on a RS485 network for > AC too. I have no idea what RS485 is...but DCC is still Alternating Current...otherwise it wouldn't work. To quote from Digitrax.com: "Each bit is divided into two halves, which are "mirrored" around zero volts. The bottom half of the signal (below zero volts) is a mirror image of the top half, but shifted over half a bit width." Also: "The DCC signal is symmetric around 0 volts." If that doesn't describe AC, I don't know what does. Sure, it's not a sine wave AC, it's a square wave...but then DC has no wave at all. The booster does not rectify the AC to DC. Honest. At least, not for NMRA DCC. Paul A. Cutler III ************* Weather Or No Go New Haven ************* > I have no idea what RS485 is... Serial communication. Klaus SignatureModelbane Europas hjemmeside: http://www.modelbaneeuropa.hadsten.dk Modeltog, internet, gratis spambekæmpelse, elektronik og andet: http://home6.inet.tele.dk/moppe Turbogrilstarter: http://home6.inet.tele.dk/moppe/tgs.html > You could simply use a toggle to switch between the two (live > overhead vs. normal 2-rail)...unless you want to run diesels/steam > with the electrics. Was that common in Austrailia? On the railway that Craig is modelling, yes - but mostly in an earlier period than he is probably interested in. All the best, Mark. (Self-Confessed Rivet Counter) <snip> > To do that so the power pick up doesn't matter, the solution is > simple... Wire both rails to the same polarity and use the catenary for the [quoted text clipped - 4 lines] > > Paul A. Cutler III Paul, while I don't have any practical experience with this, I would think that a single point of pickup (the pantograph) would be somewhat unreliable. Even with both pantographs up, that is only 2 contact points. Most 4-axle locos have 4 contact points on each rail when used in the conventional way. Peteski Your point is well taken with the older pantograph designs.... However, most modern pantographs have two or three contact points. Signature+GF+ SURGEON GENERAL'S WARNING: Books may introduce unfamiliar or confusing ideas. In the event of uncomfortable self-reflection, heat to 451° Fahrenheit ( 232.78° Centigrade or 505.9 Kelvin ) and seek television immediately. www.internationalrailfair.com www.ete.org > > <snip> [quoted text clipped - 18 lines] > > Peteski > Paul, while I don't have any practical experience with this, I would > think that a single point of pickup (the pantograph) would be somewhat > unreliable. Even with both pantographs up, that is only 2 contact > points. Most 4-axle locos have 4 contact points on each rail when used > in the conventional way. While it is a single point of contact for a pole, the shoe on the pole, IMHO, has a much bigger contact area than even 4 wheels. Think about it. How much surface area is a round wheel going to have on a piece of rail...even a flat head rail and a non-tapered wheel? Not much. A shoe, on the other hand, has a v-notch that slides along the wire. The main problem we'd have is dirt build up on the wire. What we'd usually do is run a trolley with both poles up to "scrub" the wire a bit, then drop the front pole. It'd usually run well, after that. Paul A. Cutler III ************* Weather Or No Go New Haven ************* > > Paul, while I don't have any practical experience with this, I would > > think that a single point of pickup (the pantograph) would be somewhat [quoted text clipped - 12 lines] > Paul A. Cutler III > ************* Hmmm... I think that we are discussing different pantographs. I'm thinking of a standard electric loco pantograph, not a trolley pole. Standard pantographs have flat pickup shoes (no notches) as the pantograph's position is fixed but overhead wire is not always centered. V-notches are present only on trolley poles as they can swing laterally to follow the overhead wire. Peteski > Hmmm... > I think that we are discussing different pantographs. I'm thinking of > a standard electric loco pantograph, not a trolley pole. True. Sorry about that. > Standard pantographs have flat pickup shoes (no notches) as the > pantograph's position is fixed but overhead wire is not always > centered. Also true. However, many pans have double shoes so there is two points of contact there. > V-notches are present only on trolley poles as they can swing laterally > to follow the overhead wire. Yep. Fun to watch... Paul A. Cutler III ************* Weather Or No Go New Haven ************* > > Hmmm... > > I think that we are discussing different pantographs. I'm thinking of [quoted text clipped - 15 lines] > > Paul A. Cutler III I suppose that we could beat this to death Paul... What you stated about dual shoes on a pantograph is true. But the shoes aren't the only place of intermittant contact. Unlike the real pantographs, models do not have a bypass wire at every mechanical joint. So, there is no solid connection between the overhead pickup shoes and the base. Every movable joint can be a source of intermittant contact. I rest my case. :-) Peteski > I suppose that we could beat this to death Paul... Isn't that we are supposed to do? ;-) If no one ever argued any point, we might as well give up and surf the 'net for train pics. > What you stated about dual shoes on a pantograph is true. But the > shoes aren't the only place of intermittant contact. Unlike the real > pantographs, models do not have a bypass wire at every mechanical > joint. So, there is no solid connection between the overhead pickup > shoes and the base. Every movable joint can be a source of > intermittant contact. Well, yeah. However, it's never been a problem for my club's old layout. Or let me put it this way... If we had a trolley that wouldn't go, first we'd clean the wheels. If that didn't do it, we cleaned the track. If that still didn't work, we'd clean the wire. If we still had intermittant contact, then we'd open up the model to see if there's anything internal that's wrong before we'd check the pan. IOW, the mechanical connections of the pans were never a problem on our RR. I even used a NH brass EF-1 under our wire that I custom painted. I sprayed right over the brass pans that were on the model, and I never had a problem with intermittant contact with them. Sure, I had problems with the model staying on the rails (mainline electrics don't like trolley curves), and the pan staying on the wire, but if the wheels, track, and wire was clean, my engine ran without stalling. Besides, I thought that the while point here was that a pan has only (at most) two points of contact to an outside power source vs. the 4 or more for the equivalant wheels that one would be replacing. Since when did this become a discussion about the internal mechanical/electrical connection of a pan? BTW, most if not all of our trains rely on a mechanical connection at some point for electrical contact, and I'm talking above the wheel-to-rail contact. Athearn BB relys on nothing but, from the wheel journals to the commutator. Kato uses end bearings to carry current, and on some of their models use wipers from the motor to the trucks. Overland uses bent pieces of wire to rub on the backs of the wheels to pick up the juice, while every P2K I can think of uses mechanical "clips" to force the bare wire against the circuit board. Doing trolley right (and that means live overhead) is part of the challenge of it. It's why I like it. You may as well tell some narrow gauger to broaden his rails because it's easier... LOL Paul A. Cutler III ************* Weather Or No Go New Haven ************* > > I suppose that we could beat this to death Paul... > > Isn't that we are supposed to do? ;-) If no one ever argued any point, > we might as well give up and surf the 'net for train pics. <major snip> > Paul A. Cutler III Paul, I couldn't ignore this nice writeup. You're right of course. Some peple like things easy and simplified, others like a challange. Enjoy running the trolleys! Peteski > Hi, > [quoted text clipped - 29 lines] > > Craig. With DCC , this is my personal opinion, I see NO NEED to use the overhead, as there is no advantage. Under DC yes, it's a great way to have a seperatly controlled lcoo on a layout. But DCC where you have total control of the individual locos, I would model the overhead, ensure the pantographs spring and do not fould, and leave it unpowered. -unless you really really really want the spark of the panto to be replicated ! You can do it, lets say all powerfeeds on the track are a red and a green wire. You could make the overhead wired say for the red wire and connect the overhead to the red track pickups. Won't achieve anything really control wise at all. My two cents. David Head >With DCC , this is my personal opinion, I see NO NEED to use the >overhead, as there is no advantage. Under DC yes, it's a great way to >have a seperatly controlled lcoo on a layout. But DCC where you have >total control of the individual locos, I would model the overhead, >ensure the pantographs spring and do not fould, and leave it >unpowered. >-unless you really really really want the spark of the panto to be >replicated ! There's something to be said for the 'arcing and sparking' aspect of electric traction, but I wonder how good that is for long-term operation. After all model overhead wiring is nowhere near the physical and electrical capabilities of the real thing. >You can do it, lets say all powerfeeds on the track are a red and a >green wire. You could make the overhead wired say for the red wire and >connect the overhead to the red track pickups. Won't achieve anything >really control wise at all. True, but it's an extension of DCC which doesn't seem to have been given much attention. In reality there may be RFI/EMI issues relating to doubling up of one 'rail' of the power feed from the booster which may affect decoder performance. I'm not an RF expert though so it's all speculative at the moment. Regards, Craig. SignatureCraig Dewick - Professional Train Manager (RailCorp) + HO Scale Rail Modeller http://www.railzone.org -- Galleries, Forums, Links, Data, etc.! Send email to craigd@lios.apana.org.au -- RailCorp Train Crew Council: http://www.rctcc.org Oz Rail Safety List: http://lios.apana.org.au/mailman/listinfo/aus_rail_safety > With DCC , this is my personal opinion, I see NO NEED to use the > overhead, as there is no advantage. Under DC yes, it's a great way to > have a seperatly controlled lcoo on a layout. But DCC where you have > total control of the individual locos, I would model the overhead, > ensure the pantographs spring and do not fould, and leave it > unpowered. Have you ever run a trolley? There's a darn good reason to use the live overhead if you are going to put the poles and pans up: What happens to a pan or a pole that falls off the wire? It snaps straight into the air as high as it will go. If you have dead overhead, it will now hit every catenary bridge, tunnel, guy wire, signal bridge, RR or highway bridge, etc. and either stop the whole thing in it's tracks, break the obstruction, or break off the pan/pole. This gets expensive as poles and pans ain't cheap. If you have live overhead, the trolley will stop...probably instantly as few trolley models that I've seen have flywheels. This is a great safety device and allows one to run a trolley with confidence that if a pole or pan falls off the wire, you're not going to have to fix it all the fricken' time. > -unless you really really really want the spark of the panto to be > replicated ! [quoted text clipped - 3 lines] > connect the overhead to the red track pickups. Won't achieve anything > really control wise at all. Control is not the point at all with live overhead. Most trolleys that I've ever seen are seperate RoW's from the mainline anyways, and at my old club, both trolley rails were the same polarity. Paul A. Cutler III ************* Weather Or No Go New Haven ************* > is whether there is any standard for whether the left-hand or the right-hand > rail is connected to the pantograph(s) for power collection using DCC. It depends on, how you turn the loco around. But standard is right-hand, since left is "common". > Thanks if you can provide a definitive answer to the question. Feel free to > comment in the forums at my site too if you'd like to. I'll transfer any > information from here to there otherwise. There is really no idea of using the overhead wire when running DCC. It will only cause you more problems. You have to make sure that the loco is placed correctly, Otherwise tho loco will not run. The current pickup from overhead wire is not as effective af from many wheels. You can off course use _both_ track and wire, but then a loco on the track, that is turned around, will cause a short circuit. Using overhead wire for supply makes it impossiple to do a reverse loop. Klaus SignatureModelbane Europas hjemmeside: http://www.modelbaneeuropa.hadsten.dk Modeltog, internet, gratis spambekæmpelse, elektronik og andet: http://home6.inet.tele.dk/moppe Turbogrilstarter: http://home6.inet.tele.dk/moppe/tgs.html >> is whether there is any standard for whether the left-hand or the right-hand >> rail is connected to the pantograph(s) for power collection using DCC. [quoted text clipped - 16 lines] > >Klaus Essentially if you want to mix overhead and 2-rail electrification by using only one rail for return you have to accept that your locos running on overhead are never turned with respect to the track, ie they don't use turntables or reverse loops. There is no benefit from using the overhead with DCC so why give yourself these problems. This is why DCC suppliers warn against using overhead. If you have an all electric layout using overhead with return through both rails then you have no problems, no special wiring for reverse loops, cheap and simple track circuiting etc. DCC will be Ok in this scenario. Keith > It depends on, how you turn the loco around. But standard is right-hand, > since left is "common". But it won't matter if both rails are the same polarity, which is what my club's old trolley layout was like. > There is really no idea of using the overhead wire when running DCC. It > will only cause you more problems. You have to make sure that the loco > is placed correctly, Otherwise tho loco will not run. The current pickup > from overhead wire is not as effective af from many wheels. You can off > course use _both_ track and wire, but then a loco on the track, that is > turned around, will cause a short circuit. Again, wire both rails the same polarity, and it won't matter which way the loco is pointing. Certainly, a pole or pan is not as good as 4 wheels, but then that is why one models trolleys anyways...to have that wire, to watch that pole run in and out, to watch that pan go up and down. It's what makes trolley modeling different from the rest. And if you don't use the overhead for power, be prepared to fix a lot of pans and poles over the years as they will hit obstruction after obstruction when they fall off the wire. > Using overhead wire for supply makes it impossiple to do a reverse loop. Shows what you know. If both rails are the same polarity, there is no reverse loop wiring at all! Paul A. Cutler III ************* Weather Or No Go New Haven ************* > Shows what you know. If both rails are the same polarity, there is no > reverse loop wiring at all! Shows what you don't know. If you have read what Craig wrote here: http://www.railzone.org/phpBB2/viewtopic.php?t=30 Qoute: "Hi everyone, My new layout design is coming along well. Something I've decided to do is make it an industrial setting with lots of general industry serviced mostly by rail, and I'd like to have the 'main line' feeding into the area electrified so that I can run my electric locos (Ian Lindsay 86's and brass 46's) as well as diesels." Unqoute How do you want to run diesels, with both rails beeing the same polarity ? Klaus SignatureModelbane Europas hjemmeside: http://www.modelbaneeuropa.hadsten.dk Modeltog, internet, gratis spambekæmpelse, elektronik og andet: http://home6.inet.tele.dk/moppe Turbogrilstarter: http://home6.inet.tele.dk/moppe/tgs.html > How do you want to run diesels, with both rails beeing the same polarity > ? I'd put in a toggle to switch between live overhead and normal 2-rail operation for each track so equipped...unless you are going to be running eletrics AND diesels on the same train (most times when that happened on the prototype, at least in the USA, it was for pulling trains through long tunnels...not something that one would normally need reverse loops to accomplish). In which case, you would be out of luck if you wanted reverse loops, too. If it was a case where you'd never switch the electric around, you could rely on only picking up one rail with the wire for the other polarity. I don't know much if anything about Austrailia rail (other than they got some New Haven G-4a 4-6-0's during the war) and how they operated their electric service. But on the New Haven, in the electified zone, diesels (and steam) were the exception, not the rule...unless one counts New Haven, CT where they changed locos. But, if I wanted to model an electrified mainline, a toggle switch or relays based on occupancy would be my answer for solving the problems of live overhead. Either way, it is not "impossible" to have a reverse loop with live overhead. My club, the South Shore Model Railway Club (www.ssmrc.org) had two reverse loops for 45 years...and there were no gaps, no toggles, not much of anything, really. Just rail and wire and a bunch of scenery. In fact, in one of our loops that was under the scenery, the trolley wire was replaced with a brass trough (or "C" section beam) which made it nigh impossible for the pole to lose contact while in the tunnel. Worked well, too. It even had a ramp on each end for pans... Paul A. Cutler III ************* Weather Or No Go New Haven ************* > I'd put in a toggle to switch between live overhead and normal 2-rail > operation for each track so equipped... But why all the extra work, when all locos can run without modifications on simple 2 rail ? > Either way, it is not "impossible" to have a reverse loop with live > overhead. My club, the South Shore Model Railway Club (www.ssmrc.org) had > two reverse loops for 45 years... I guess you didn't run DCC and mixed diesel/electrics. Klaus SignatureModelbane Europas hjemmeside: http://www.modelbaneeuropa.hadsten.dk Modeltog, internet, gratis spambekæmpelse, elektronik og andet: http://home6.inet.tele.dk/moppe Turbogrilstarter: http://home6.inet.tele.dk/moppe/tgs.html > > I'd put in a toggle to switch between live overhead and normal 2-rail > > operation for each track so equipped... > > But why all the extra work, when all locos can run without modifications > on simple 2 rail ? Because that's why you model trolley in the first place. Why do people insist on modeling narrow gauge? It's so much easier (and cheaper) to simply model standard gauge. But they do it *because* it's narrow gauge...because it's different. Same with trolley. > > Either way, it is not "impossible" to have a reverse loop with live > > overhead. My club, the South Shore Model Railway Club (www.ssmrc.org) had > > two reverse loops for 45 years... > > I guess you didn't run DCC and mixed diesel/electrics. No, we didn't. Our old club was DC analog all the way. We did have a diesel under the wire, but it used a pole, as well, and yes, there's a prototype for it. On the real thing, the trolley used the wire for their signalling detection, so all diesels under the wire also needed poles to trip the signal detection system. On our new layout, we do plan to mix the two, but not at the same time. We plan to have a switch between overhead DC and 2-rail DCC...or maybe DCC with the overhead (we haven't figured that one out yet). Paul A. Cutler III ************* Weather Or No Go New Haven ************* > No, we didn't. Our old club was DC analog all the way. We did have a > diesel under the wire, but it used a pole, as well, and yes, there's a > prototype for it. On the real thing, the trolley used the wire for their > signalling detection, so all diesels under the wire also needed poles to > trip the signal detection system. And I'm rather sure that that is a common used system in Aussie ? Klaus SignatureModelbane Europas hjemmeside: http://www.modelbaneeuropa.hadsten.dk Modeltog, internet, gratis spambekæmpelse, elektronik og andet: http://home6.inet.tele.dk/moppe Turbogrilstarter: http://home6.inet.tele.dk/moppe/tgs.html >> No, we didn't. Our old club was DC analog all the way. We did >> have a diesel under the wire, but it used a pole, as well, and yes, [quoted text clipped - 3 lines] > > And I'm rather sure that that is a common used system in Aussie ? Common enough on our tramways! ;-) > > No, we didn't. Our old club was DC analog all the way. We did have a > > diesel under the wire, but it used a pole, as well, and yes, there's a [quoted text clipped - 3 lines] > > And I'm rather sure that that is a common used system in Aussie ? Not at all. Just saying that is what *we* did to get a diesel under our old DC analog live overhead wire...and that as silly as it sounds to have a diesel switcher with a pole on it, that really happened on the prototype in the USA. Paul A. Cutler III ************* Weather Or No Go New Haven ************* >My club, the South Shore Model Railway Club (www.ssmrc.org) had >two reverse loops for 45 years. And then? -- Ray >>My club, the South Shore Model Railway Club (www.ssmrc.org) had >>two reverse loops for 45 years. > > And then? > -- > Ray And then, if you look at the web site, they're building a new layout. J. Bright >>>My club, the South Shore Model Railway Club (www.ssmrc.org) had >>>two reverse loops for 45 years. >> >> And then? > >And then, if you look at the web site, they're building a new layout. Thank goodness. I had this nasty feeling that they had been stolen or something. Close call, eh? -- Ray > >>>My club, the South Shore Model Railway Club (www.ssmrc.org) had > >>>two reverse loops for 45 years. [quoted text clipped - 5 lines] > Thank goodness. I had this nasty feeling that they had been stolen > or something. Close call, eh? Well, the SSMRC was est. in 1938 as the Quincy Model Railway Club, and after a few moves during and after the war, moved to the basement of a small Weymouth, MA shopping plaza in 1953. We stayed there until 1998 (eventually, the layout grew to 2500 sq. ft.) when we moved to a former Naval Ammuntion Depot bunker in Hingham, MA. Our new layout will be over 6300 sq. ft., so one can see why we moved. Just like our old layout, we plan to have Eastern 3' narrow gauge, live overhead trolley, and, of course, standard gauge. Paul A. Cutler III ************* Weather Or No Go New Haven ************* > I'd put in a toggle to switch between live overhead and normal 2-rail >operation for each track so equipped...unless you are going to be running >eletrics AND diesels on the same train (most times when that happened on the >prototype, at least in the USA, it was for pulling trains through long >tunnels...not something that one would normally need reverse loops to >accomplish). http://www.railpage.org.au/pix/diesel/42210-8011-8647-8635-8642_CA16_Engadine_2- 7-99.jpg http://www.railpage.org.au/pix/diesel/42219-42220-8630-8631-8642_CA16_Engadine_M arch-1999.jpg http://www.railpage.org.au/pix/diesel/8021-8011-8609-8612-8614_CA16_Waterfall_8- 7-99.jpg http://www.railpage.org.au/pix/diesel/42213+422xx+86xx+86xx+86xx_Como.jpg --- Difference of Hillary & Panama Canal? Ones a busy ditch, the other's.. --- David Johnson usenet.at.trainman.id.au http://www.trainman.id.au ------------------------------------ These comments are made in a private capacity and do not represent the official view of RailCorp. >> Shows what you know. If both rails are the same polarity, there is no >> reverse loop wiring at all! >Shows what you don't know. >If you have read what Craig wrote here: >http://www.railzone.org/phpBB2/viewtopic.php?t=30 >Qoute: >"Hi everyone, >My new layout design is coming along well. Something I've decided to do >is make it an industrial setting with lots of general industry serviced >mostly by rail, and I'd like to have the 'main line' feeding into the >area electrified so that I can run my electric locos (Ian Lindsay 86's >and brass 46's) as well as diesels." >Unqoute >How do you want to run diesels, with both rails beeing the same polarity >? Thanks for bringing that up Klaus. I could of course decide to make the layout fully-electric traction based and since I'm in Sydney that's almost feasible, but I'm looking at using normal 2-rail power delivery (albeit using DCC instead of straight DC), and was wondering about using live overhead as well because it's sort of a waste of effort to make overhead wiring, etc. if it's just sitting there looking pretty and not doing anything functional. 8-) Craig. SignatureCraig Dewick - Professional Train Manager (RailCorp) + HO Scale Rail Modeller http://www.railzone.org -- Galleries, Forums, Links, Data, etc.! Send email to craigd@lios.apana.org.au -- RailCorp Train Crew Council: http://www.rctcc.org Oz Rail Safety List: http://lios.apana.org.au/mailman/listinfo/aus_rail_safety > I could of course decide to make the > layout fully-electric traction based and since I'm in Sydney that's almost [quoted text clipped - 3 lines] > wiring, etc. if it's just sitting there looking pretty and not doing > anything functional. 8-) Do as the rest of us - leave it beeing pretty :-) "My" model railroad is electrified allmost all over, except for shunting tracks and the harbour. I you look at http://www.modelbaneeuropa.hadsten.dk/over.html you will on the left hand see a rough trackplan showing where the numbered photos are taken. Click on the photos to the right and see them in lager size. Klaus SignatureModelbane Europas hjemmeside: http://www.modelbaneeuropa.hadsten.dk Modeltog, internet, gratis spambekæmpelse, elektronik og andet: http://home6.inet.tele.dk/moppe Turbogrilstarter: http://home6.inet.tele.dk/moppe/tgs.html >Hi, > [quoted text clipped - 29 lines] > >Craig. Craig, the standard answer to using DCC fed through the Catenary is "Don't". It's unnecessary as you have already wired your track up and it exposes you to a variety of additional and unnecessary complications. Keep the overhead as a scenic extra and stay on the track feed. SignatureIan Birchenough > Craig, > the standard answer to using DCC fed through the Catenary is "Don't". > It's unnecessary as you have already wired your track up and it exposes > you to a variety of additional and unnecessary complications. Keep the > overhead as a scenic extra and stay on the track feed. If you have a dead overhead, and you run with the pans and poles up, then what do you do when they fall off the wire? I'd be watching them get slammed into all kinds of obstructions and getting damaged. If I use the overhead as power, I'd be watching my trolley stop instantly and not be damaged. Paul A. Cutler III ************* Weather Or No Go New Haven ************* Are you running electric only and honestly ? If YES make the panto one polarity, and the track the other so reverse loop should never be a problem after that. But you will have to alter your pickups etc. You desire to protect the panto is admirable and it is your railway. Just pay attention to the reverse loop problems. To me a train derailing takes litle time and if the panto get damaged, it would take a decent crash to do so, and if such force does occur, it will not matter if it is powerered or not - a derailment means wheels off the rails, and panto powered or not , the loco will stop and still cause that crash !!! So I would think it is still not needed, and will not protect your trains. Regards, David Head > Are you running electric only and honestly ? If YES make the panto one > polarity, and the track the other so reverse loop should never be a > problem after that. But you will have to alter your pickups etc. Well, yeah. I've done that several times, everything from a Bachmann LRV to a brass steeple cab. Just kinda goes with the territory. > You desire to protect the panto is admirable and it is your railway. > Just pay attention to the reverse loop problems. Um, what reverse loop problems? There aren't any with both rails being the same polarity. > To me a train derailing takes litle time and if the panto get damaged, > it would take a decent crash to do so, and if such force does occur, it > will not matter if it is powerered or not - a derailment means wheels > off the rails, and panto powered or not , the loco will stop and still > cause that crash !!! So I would think it is still not needed, and will > not protect your trains. Have you ever run a trolley? I have, and trust me it doesn't take much to damage some pans and poles. For example, when a pole pops off the wire, it tends to spin a bit. It wouldn't take long for a pole to be flipped over backwards and wedged under a catenary bridge. When a pan pops off the wire, it will hit the next catenary bridge and crash stop the train if it keeps going. Since I've had to resolder a couple over the years, it's no fun. It actually got the point where we detached the roof of our brass steeple cab and applied it back on with a bit of velcro. When it snagged, it only popped the roof off (and this is with live overhead!). But that was when our overhead was built, it was built for poles only. We modified it for pans, but obviously we didn't modify it enough. LOL BTW, derailing was not really a problem. Oh, sure, we had a lot of them (street running and all), but the poles usually stayed on the wire during a derailment. Paul A. Cutler III ************* Weather Or No Go New Haven ************* > Um, what reverse loop problems? There aren't any with both rails being > the same polarity. Or with DCC and dead overhead wire. Klaus SignatureModelbane Europas hjemmeside: http://www.modelbaneeuropa.hadsten.dk Modeltog, internet, gratis spambekæmpelse, elektronik og andet: http://home6.inet.tele.dk/moppe Turbogrilstarter: http://home6.inet.tele.dk/moppe/tgs.html > > Um, what reverse loop problems? There aren't any with both rails being > > the same polarity. > > Or with DCC and dead overhead wire. Well, you still have to have an auto-reverser with 2-rail DCC...just not with live overhead with both rails the same polarity. Put it this way, live overhead with both rails the same polarity is just like old 3-rail Lionel in that reverse loops pose no electrical problems. Why? Because the inside and outside rails never change polarity. Paul A. Cutler III ************* Weather Or No Go New Haven ************* Pac Man, Thankyou for your discussion, I enjoy it. I also appriciate your experiance. You answered my questions proving to me you know what you are doing and not comming in bliond. So I expect your application of DCC will work. I have a 4x8 tramway I were building with another person. It got to the platered street stage. It was to be overhead driven with both rails joined as the one polarity. Buy we have drifted apart, the tramway stored. I have one 4-wheel tram for it, never used. So your situation is very interesting. Wiring this tramway would be easier under DCC. The technical gurus may work out some sort of biased supply tied to the DCC that used the catenary and if you depole a relay cuts the loco's power ( but that adds alot of complexity to the layout, when it is fairly simple to switch the catenary as well as the track , as needed. Wish you well, and do come back to tell us how it goes practically !! Regards, David Head > Pac Man, > > Thankyou for your discussion, I enjoy it. How long has it been for a good ON TOPIC thread on r.m.r? Seems like forever... LOL > I also appriciate your > experiance. > You answered my questions proving to me you know what you are doing and > not comming in bliond. So I expect your application of DCC will work. Your welcome. :-) And it should work *if* you spend a lot of effort on your wire. You should try to get good wire (I think we used Nickle-Silver wire) and stretch it tight when soldering. The NMRA should have a bunch of trolley info in their Standards and RP's on their website (of course, USA practice, but still should be good). > I have a 4x8 tramway I were building with another person. It got to > the platered street stage. It was to be overhead driven with both rails [quoted text clipped - 3 lines] > for it, never used. So your situation is very interesting. Wiring this > tramway would be easier under DCC. Are you going to be running standard equipment under the wire? Ie, steam, diesels, etc.? Or just trolley? > The technical gurus may work out some sort of biased supply tied to > the DCC that used the catenary and if you depole a relay cuts the > loco's power ( but that adds alot of complexity to the layout, when it > is fairly simple to switch the catenary as well as the track , as > needed. Wow. An interesting solution. But I think I'd rather a big toggle, as when the pole pops off by accident, wouldn't it keep the trolley running? Or short it out if you've wired both wheels on the trolley the same polarity. > Wish you well, and do come back to tell us how it goes practically !! OK. We're just getting into the rail laying stage and getting to the point where we can add catenary to our first section. Paul A. Cutler III ************* Weather Or No Go New Haven ************* > Your welcome. :-) And it should work *if* you spend a lot of effort on > your wire. You should try to get good wire (I think we used Nickle-Silver > wire) and stretch it tight when soldering. The NMRA should have a bunch of > trolley info in their Standards and RP's on their website (of course, USA > practice, but still should be good). That why it's stored until I get the other guy back or I sell it. The other guy had lots of trams, I were more interesting in the layout as such. > Are you going to be running standard equipment under the wire? Ie, > steam, diesels, etc.? Or just trolley? Trams & trolly 99%. American or Aussie, the guy had a few models. Todaty it is stored. Until I get reconnect with the guy it is stored, for if I try to sell it, he get 55% as he put money into it as well, ie it is not mine, I'm the custodian. Regards, David Head |
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