I’ve got a new layout being started, and I’ve got a few questions that I hope someone here can answer.
Here’s a pic of the track plan:
It’s Mike Bell’s N scale Pennsy layout from Great Model Railroading 1991 issue.
We’ll be running DCC, using an MRC Prodigy (original), but only about 1/3 of my motive power is decoder equipped so far. Now, as you can see, the layout has a serious reverse loop. I was thinking about getting an MRC Reversing Module for it. Also, while it’s got that one reverse loop to change direction, once you’ve changed direction, there’s no way to change back without stopping in the tunnel, backing up a ways and then flipping the turnout to the other track and going ahead again. I’d like to add a crossover someplace to get back to going my original direction.
So, here’s my questions:
Is an MRC Reverse Module the way to go?
How many would I need?
Where is the best place to put them?
Just what would happen with them with a non-decoder equipped loco?
Where would be the best place to put the new crossover?
Also, I’ve got a permanently-coupled PA/PB combo sharing a single decoder. Any likely problems for this with a reverse module?
Currently, the only place I see a reverse loop is the inside loop on the lower right. There is only one area that needs to be separated and that is the short section of track that goes under the bridge. IF you iso;ated it on the close side of both turnouts and place the auto reverse module on that section of track, you will be fine.
I’m don’t think MRC allows DC engines to run on their DCC system. With the Digitrax and Bachmann you can do that.
You need one reversing module per reversing loop and with DCC reversing modules are the way to go. No switches needed.
I dont understand your grades and elevations so I don’t know where to put another reversing loop. See if you can pencil in the grades. Where the 0 is, 1", 2" etc so you know where your grades and elevations are. Very important.
I went over the track plan, and added the grades & elevations, doing them color coded. All black track is at 0"; yellow track is a 4% WS incline; red track is at 2". I also added a section of blue track to show the current suggested isolated section for the return loop.
The inclines are set so that the tracks at the top of the layout, where they are closest, just before the bridge, are at the same elevation.
Reverse modules are connected to the “track bus” side of your DCC system, so they all fall under NMRA specifications. Therefore, all reverse modules must behave the same way, so they are all interchangeable. I personally use a Tony’s Trains PS-REV unit, and I love it. The PS-REV has been replaced by a newer model, by the way. The Tony’s units are all solid state, while many others (like the MRC, I think) are relay based. In general, solid state technology is both more reliable and faster-switching than relays.
It looks like you just need one.
You should insulate the longest section of “reverse loop” that you can. It’s OK to include sidings in your “protected” section. The big issue with reverse loops is to make sure that the front of the train doesn’t leave the “protected” section before the last car enters it.
If you are hot-tempered and prone to throwing things, the loco will end up smashed against the wall on the far side of the room. DC-equipped locos do not behave the same as DCC-equipped locos with respect to auto-reversers. You will see them enter the loop correctly, but when they get to the other end, they will ping-pong and go into reverse as the polarity flips. This will happen again at the other end. Sometimes, the engine will simply stall and short out instead, depending on how fast your reverser flips vs. the circuit breaker on your DCC system.
All DCC systems are required to allow one anolog locomotive, or anolog consist to run on address “00” to receive NMRA certification.
With anaolog locomotives, as they enter the reverse loop, no action is needed. When they reach the other end, and the reverse loop changes to match the exit track, you’ll have to change the direction on your throttle or the train will backup back into the reverse track.
The reverse section only has to be as long as your longest consist of locomotives. When I converted to metal wheel sets on my rolling stock, I was concerned they would create problems in the reverse track, but it’s not an issue.
Amazingly, I’ve discovered, that the MRC reverse module costs more than the DigiTrax unit. The DigiTrax unit is easier to install and, I believe, is a higher quality item.
I’m afraid I will have to respectfully disagree on this one. Any time you can simultaneously bridge the gaps at both ends of your reverse section, you will have a problem. The most common situation is a locomotive, with lots of metal wheels wired together, whenever it crosses the gap. You will also have problems with illuminated passenger cars with metal trucks, where at least some of the wheels are wired together. An illuminated caboose will work the same way. You are less likely to notice a problem if you have plastic trucks, because the metal wheels aren’t connected to each other. Also, if you use insulated rail joiners with a piece of insulator sticking up between the rail sections, it may be long enough that it actually rises above the top of the rail, preventing a single wheel from bridging the gap.
I run metal-wheel trains through my reversing-crossover too. The reversing section is only a few feet long, longer than the engine consists but shorter than most trains. Most of the time, I get away with it. The passenger train never fails to short, though, and I get hiccups with the others on occasion, too.
MRC does NOT run DC locomotives on the DCC system. I am PRETTY SURE this is correct. Nowhere on MRC’s website does it say it does. The statement about NMRA cert is misleading even if it is true. What matters is what YOUR system will do.
The MRC DCC systems will run a single non-decoder equipped loco, I’ve done it for a long time on the old layout. But, the MRC Reverse Module says that it will not work with non-DCC locos.
I’m now actually looking at Tony’s PSReverse unit rather than the MRC unit. Pretty much the same price, and Ton’y sounds os tho it’s better and does more.
I was figuring that the area at the top of the layout was best for adding the crossover/reverse loop. But, where would I put the second reverse module for that?
I respectfully conceed your point about the metal truck, we in N scale don’t run into those very often. I forgot to mention the passenger cars, not all are set up for lighting kits. I did have to modify the Kato AmTrack cars to prevent problems with the reverse track.
None of the other rolling stick with metal wheels have been an issue. I assume the brief contact with both rails is insufficient to cause a problem.
Having dealt only with DigiTrax, I guess I made an assumption. I cant believe that the other DDC manufacturers are so derelict as to prevent running older epuipment. It is possible that they aren’t fully certified by the NMRA.
If Im wrong, I appologize, but it seems logical to allow backward compatibility for older equipment.
The MRC Command 2000 and the original Prodigy (the one Bill has) will run an analog engine. The Prodigy Express and the Prodigy Advanced will not.
From the Prodigiy Advanced manual:
Digitrax does allow you to disable analog engine support to prevent slowing the system response. Also, if you are not running an analog loco, as long as you have the speed set to zero for the analog loco, it will not affect the response.
Bill,
If you can move the tracks to get enough seperation at the middle of the top to get a another track between the top two, you could put a turnout at the end of the red passing siding and have it run along beside the bottom yellow line. This would get you little bit of length in the reversing section and then you could have it meet the yellow line near the botoom of the grade. The down side to this is having a turnout on a 4% grade.
