Reversing loop in DCC, Baseboard joints and Couplings

[Smileyjon]

Advice and help needed on three subjects please !

 

1 How do I wire a simple return loop in DCC and I cannot understand how it can handle a two engine setup like a Garratt or a double header.

 

2 What is the easiest way to join two baseboards together to ensure the track is perfectly aligned.

 

3 I have just bought some lovely Bachmann coaches but they use complicated hook type couplings, a little like the old Triang ones.  Easy to couple up but how on earth does one uncouple on the layout. And the coaches have rubbery corridor ends but they seem a long way apart !

 

That's all for now folks 

 

Any help to a complete novice would be most welcomed   

 

Thanks

 

Jon

[johnb]

On item 2 you really need to use pattern makers dowels fitted on the ends of the board, these will ensure that the boards always line up.

The boards then need to be held together, I use toggle clips, others use bolts, and some use the plain straightforward clamps/cramps.

Plenty of information to be found on here in a variety of threads.

 

On double heading there are two options for individual locos, the very simple one is to give the chip on each loco the same id, or to do consisting, that is bit more complex, but should be covered in your controller manual.

 

As for the Garrett, don't know the power arrangements on those, but one way would be to use two chips, one per motor each with the same id, or if the internal wiring is common to use one chip for both motors, again this should be in the loco instructions.

 

Reverse loops are a dark secret to me as I just have end to end layouts!!! Others will be on here soon to tell you about those, again plenty of threads on here, just do a search for 'reverse loops'.

 

Bachmann coach couplings, well I take them off and use the NEM version Kadees

 

Search around on here you will find a lot of information for these queries

 

John

[HLT 0109]

Jon,

 

Reversing loops occur when you turn track back on itself (or create a triangle), thereby having to join two rails of opposite polarity.  You must therefore isolate the length of track that causes the short (ie the whole of the reversing loop (or side of the triangle) and provide it with an independent, switchable power supply.  Isolating the track is by use of insulating rail joiners at both ends of each rail, thus preventing the power supplied to the rest of the layout from feeding the length of track in question. The best way to provide switchable power to the isolated track is via a reversing loop module ("RLM");the module takes its power from the power bus (ie from outside the reversing loop) and feeds it to the isolated track.  As a loco crosses the isolated rail joiners on entering the reversing loop, the RLM may detect a short - if it does, it will immediately reverse the polarity of the power it supplies, allowing the loco to continue its journey.  When it gets to the end of the isolated section, the same thing happens and you don't notice the change in polarity.  I say "may" in the previous sentence because, either on entry to or on exit from the isolated section, the polarity will be correct.  The point to note is that it is only the power supply to the reversing loop that is switched - the rest of the layout is not affected.  You must however ensure that your length of isolated track is long enough to accommodate all pickups in any given train.  Double heading or banking is no problem (given compliance with the previous sentence).

 

I understand that some DCC controllers detect a short too quickly for some RLMs but I have had no problems with Hornby RLMs and NCE PowerCab.

 

I hope this is clear.

 

Harold.

[Smileyjon]

John . . .  many many thanks.  I'm off to look up pattern makers dowels and as for NEM version Kadees (something from a starship I'm guessing) . . they all look slightly different some with gear boxes, some magnetic, whiskers and dozens of variants and I wouldn't know where to begin.  More research I suspect  

 

Harold . . . I have discovered that mine will be a reverse loop but as loco's have 'pick ups' on various wheels including tenders I'm trying to get my old head around how a little box of tricks controls, for example, the front wheels shorting and the short is detected and polarity changed whilst the rear wheels have yet to leave the the original polarity part of the track . . .  drives me mad thinking about it . . .

 

Thanks to both for your time and help.. Jon

[Chimer]

Bachmann/Triang couplings (aka tension-locks) - the usual uncoupling device is a sprung ramp (e.g. Peco part SL 29 or a strip of bendy plastic) which when the tension is unlocked (i.e. the vehicles are pushed together) lifts the hooks meaning they can be separated by the train loco pulling one bit away from the other.  So you pull the couplings you want to split over the ramp, stop, back up fractionally (to release the tension) and pull away - in theory!  Or push the couplings onto the ramp, stop and back away - in theory!  You will gather from my use of "in theory" that this is not an exact science, and I have about a 50% success rate, which is highly frustrating when doing a shunting puzzle.  I believe the situation can be improved by being meticulous about aligning the heights of the couplings, and I really must get around to it.  Many on here recommend alternatives (often Kaydees) which can be fitted into the coupling pockets, and offer more realistic shunting manoeuvres, but I gather these equally require careful setting up to work successfully.

 

Cheers

 

Chris

[BR60103]

Jon: the reversing section has to be long enough to take your entire train. This may mean that you have to put the insulating gaps right at the end of the points. If you have a "loop" that is more complicated than a single track, there are extra complications that will require thinking.* If you often run trains that take up the full loop, you may end up stopping them to change the points for exit.

 

If the reversing section is shorter than the train, metal wheelsets at the end will reset the reversing module to entry, then the wheelsets at the front will set it for exit, entry, exit, lather, rinse, repeat.  I have heard the reversing module go click clack click clack as this happens.

 

* if you have a set of sidings inside the loop, or a station.

[BR60103]

Kadee couplings:

There are 4 NEM types (Nos. 17-20) of different lengths. Different coaches require different lengths -- try a few until you like the look.  If you don't have the device that separates more on curves, you may have to leave a bit of space.

One of the manufacturers didn't grasp the idea of a standard height for couplings -- they have 3 variation of shank from flat to cranked. Flat is at the correct height and there are no Kadees that fit the others.

The other 40 types of Kadee are for assorted applications, usually American, where the coupling has to be mounted on the floor of the car or in a box that was provided. Kadee website has mounting height specifications for all their products.

 

For the Triang type couplings, you can make a hand uncoupler out of a piece of strip metal, with a bend at the end, or a flat sheet of plastic with a handle. Put under the couplings and lift.

[Yardman]

Advice and help needed on three subjects please !

 

1 How do I wire a simple return loop in DCC and I cannot understand how it can handle a two engine setup like a Garratt or a double header.

 

2 What is the easiest way to join two baseboards together to ensure the track is perfectly aligned.

 

3 I have just bought some lovely Bachmann coaches but they use complicated hook type couplings, a little like the old Triang ones.  Easy to couple up but how on earth does one uncouple on the layout. And the coaches have rubbery corridor ends but they seem a long way apart !

 

That's all for now folks 

 

Any help to a complete novice would be most welcomed   

 

Thanks

 

Jon

Check out this page on DCC wiring.

http://a19modelrailwayclub.org/tonys-dcc-workshop/balloons-wyes-reversing-modules/

[big jim]

how about using a gaugemaster dcc reverse loop module, ive got one on my fiddle yard as it is sandwiched between the up and down lines of my layout, as the leading wheels of the loco pass over the insulating joint into the yard it detects a short and throws the polarity of the whole yard to suit, a simple 2 wire connection too

 

so easy to use and works everytime

 

http://www.gaugemaster.com/item_details.asp?code=DCC40

[melmerby]

Jon,

 

 

I understand that some DCC controllers detect a short too quickly for some RLMs but I have had no problems with Hornby RLMs and NCE PowerCab.

 

 

Harold.

The LDT reverse loop module does not create a short so can be used with any DCC system. You do have to have a detection zone each end though (long enough for the loco/locos)

 

Keith

[34theletterbetweenB&D]

... as loco's have 'pick ups' on various wheels including tenders I'm trying to get my old head around how a little box of tricks controls, for example, the front wheels shorting and the short is detected and polarity changed whilst the rear wheels have yet to leave the the original polarity part of the track ...

 In case it isn't clear from the above answers, the method whether using switching by reverse loop module or from points, is that the supply is matched either side of the one of the two isolating breaks in the track over which the train is running at the time. The reverse loop module does this very quickly when the short is detected as those front wheels go over the isolating break at the entry to the reversing loop, so there is no shorting after that as the track supply is then in phase both sides. When the same train exits the reverse loop the module again quickly 'flips' phase in the loop so that there is now a match either side of the isolating break at the exit. (DCC supply does not determine movement direction, so changing the phase to match does not affect movement.)

 

For this to work, the train needs to be no longer than the isolated section of the reversing loop, so that only one of the isolating breaks is traversed at a time. If the isolating breaks are made immediately on the diverging roads of the point that creates the reverse loop, then this condition is automatically satisfied; as an overlong train will mechanically foul on the point, what with there usually being some overhang of 20mm or more from wheel contact to vehicle end.

[Smileyjon]

I responded to everyone yesterday and now it's vanished . . . .  weird.

[Smileyjon]

Kadee's arrived today . . .  tools required list included, 10 year old eyes and dexterity, endoscope, 20 times magnifier light and clockmakers tool set!

 

They's Magne-Matic metal ones . . . . H0 scale !

 

Scared now  no idea where to start . . . so many little bits !

[HLT 0109]

I'm trying to get my old head around how a little box of tricks controls, for example, the front wheels shorting and the short is detected and polarity changed whilst the rear wheels have yet to leave the the original polarity part of the track . . .  drives me mad thinking about it . . .

 

Jon,

 

In the case you site - the tender wheels are on track where the polarity remains unchanged but the front wheels having entered the reverse loop, cause the polarity in the loop to change. The whole loco is now using the same polarity.  When the loco reaches the other end of the loop, the front wheels detect a short and cause the polarity in the loop to change back and the loco proceeds.

 

I should stop worrying about it and accept that it just works - as I do with most things electronic!

 

Harold.

[BR60103]

Jon:

My little tip for Kadees. If you have to put a spring back in the knuckle, run a length of fine thread through the length of it first (6" should do). Pick it up with either Kadee's tool or an X-Acto knife a couple of coils from one end (probably the right end). put on the first prong, compress, the put over second prong.

Without the thread, add to the instructions "search fruitlessly for spring over a 10-foot radius".

Cheers.

[Chimer]

Hi Jon

 

Posts #6 to #16 pretty well sum up why I'm sticking with DC and tension locks .....

 

Chris

[knitpick]

Jon:

My little tip for Kadees. If you have to put a spring back in the knuckle, run a length of fine thread through the length of it first (6" should do). Pick it up with either Kadee's tool or an X-Acto knife a couple of coils from one end (probably the right end). put on the first prong, compress, the put over second prong.

Without the thread, add to the instructions "search fruitlessly for spring over a 10-foot radius".

Cheers.

 

OK slightly off topic but . . .

 

Thanks for that BR60103.  Using thread is a very neat idea, though to date (touch wood) I've not had problems replacing the coiled spring - albeit I have threaded the spring longwise on a small diameter screwdriver. 

 

The next question is - anyone any good ideas for replacing the "L" shaped spring behind the knuckle on NEM style Nos 17, 18, 19 and 20 couplers?  I've used small pliers for this but have bent the odd spring such that it is ineffective.

[DAVE1562]

Hi jon,... had a psx-arsc reverser on my last layout (gwr exe valley.... on this rm web) on a return loop... do not worry about double headers or garratt.. as long as the loop is longer than the train length the polarity switches with the correct orientation on entry or exit of the loop.....

[ejstubbs]

Kadee's arrived today . . .  tools required list included, 10 year old eyes and dexterity, endoscope, 20 times magnifier light and clockmakers tool set!

 

They's Magne-Matic metal ones . . . . H0 scale !

 

Scared now  no idea where to start . . . so many little bits !

 

 

Did you get the height gauge (Kadee #206)?  It's pretty much essential if you want to use the magnetic uncouplers.  If you are using the Kadee NEM fitting couplings it can also highlight any stock which has the NEM pocket at the wrong height (usually earlier NEM_fitted Bachmann stock).

 

I've found that Kadee NEM couplings work best on my stock with a shim of 10thou plasticard slipped in on the underside of the NEM shaft - it removes any tendency to 'droop'.  (Although not all NEM pockets need this: if you can't get the shim in, it's probably not needed.)

 

If you are using any of the other types of Kadee coupling (eg the apparently ubiquitous #5, or the whisker couplers which I personally prefer) then you will find yourself having to be a bit more creative.  Useful tools for this include the Kadee #246 2-56 drill & tap set, and a selection of 2-56 button head machine screws (I get mine from modelfixings.com - you need to get the 1.3mm hex key to fit as well).

 

The other tools I have found useful are fine tweezers, and a magnifying visor like this one.  The Kadee #237 trip pin pliers can be useful to tweak trip pins which just won't clear the uncoupling magnet, although I haven't had to use mine in anger yet.

 

It may seem a bit fiddly but the end result looks miles better than tension lock couplings IMO - and I love being able to just lift a vehicle out of a train without having to faff about getting the TLCs unhitched.

 

There's quite an extensive thread about Kadees here.

 

(I wouldn't worry too much about the tiny springs on the coupling knuckles - I haven't had to replace one on any of my stock yet.  And you do end up with plenty of them, since Kadee always put spares in with each set of couplings!  Just make sure you keep them somewhere safe 'just in case'.)

[BR60103]

The next question is - anyone any good ideas for replacing the "L" shaped spring behind the knuckle on NEM style Nos 17, 18, 19 and 20 couplers?  I've used small pliers for this but have bent the odd spring such that it is ineffective.

I've had to replace a couple of these. I don't have a good solution; I tend to add extra bends to them (not on purpose!)  I think one side of the mount has a little recess that the little prong goes into.  I have some rather sharp tweezers (sprung closed) that I use and I think this is what gives the new bend. They seem to move a bit sideways when holding the fine wire. Anything bigger won't fit in the space.

I've seen very few instances where these springs have come out, so the supplied spares last a long time.

[Smileyjon]

Thanks Harold, but . . . . my loco has two motors, six coupled pairs at the front and the same at the back.  But on your advice I'll assume it will okay 

 

And big thank you to Dave as well 

 

And . . .  a big thank you to everyone else regarding the Kadee's . . .  there were some spare springs in the pack but one escaped . . . boy do they go.  Gone forever I guess.  Anyway, they assemble quite neatly and the Bachmann ones were easy to remove (one little screw) but the screws were too short to attach the Kadee's so I'm unable to report back on the results until I source slightly longer ones !

 

Such fun 

[HLT 0109]

Jon,

 

The point is that, once the polarity in the reverse loop has changed, it will stay in that polarity until a short at the other end of the loop makes it change back.  So it doesn't matter how many pickups or motors there are crossing the initial entry point - until the one that crossed it first, tries to exit the other end of the loop.

 

Harold.

[Smileyjon]

Thanks for that reassurance Harold . . I expected the rules would be different for a loco with two motors.  What do I know eh !

[Smileyjon]

Well it seems to work okay . . just had a quick test, but the sound stutters momentarily which is a shame but I'll live with it.