Help Please - DC Wiring Problem - Reverse Loop ?

T

twojags

Registered
26 Nov 2009
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I am in need of help and advice regarding the installation of Analogue DC power to my layout and would be very grateful for any assistance from members.
I am attempting to create a G Gauge garden railway loosely based on the popular narrow-gauge railroads of Colorado (especially the Durango & Silverton and Cumbres & Toltec lines).

Track laying is virtually complete apart from the connecting section on the right indicated by the trestle bridge on the attached plan.
The layout is roughly 24’ x 16’ and incorporates elevations from ground level (“Durango Wells”) rising to around (“Crystal Springs”) to a maximum height of around 10” in the central mountain section (Lumber Camp). The grades are pretty steep, but I am hoping that that my powerful Bachmann Spectrum and LGB locomotives will be able to surmount them with short passenger or freight trains.

I am using Analogue DC power and my problem is how best to wire up the layout in ‘blocks’ to permit two trains to operate simultaneously, one on the lower oval and the other on the mountain section.

My more immediate concern is that whilst initial test runs using my trusty Stainz loco worked fine, but since connecting the last section of curved track on the loop to the right of the Lumber Mill trains refuse to run. I used my newly acquired multi meter and established that whereas there was a healthy 18 volts DC reaching the track it suddenly dropped to zero.

I was a little perplexed but with the help of my cousin we were able to isolate the problem by disconnecting the track as shown on the simplified plan. However, future operations will be severely restricted to the outer oval until the problem has been corrected.

I suspect that by connecting the final piece of sectional track I had inadvertently created a reverse loop thereby opposing polarities (not immediately apparent from the plan). As you can gather my electrical knowledge is fairly basic (well just enough to stop me from electrocuting myself so far) but in studying the plan a reverse loop does appear to be the likely cause of the problem.

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I have acquired a S/H LGB 1015K Reversing Loop Set but am unsure where to actually locate this as I understand that you can only run trains into a reverse loop from one direction? I am thinking that it might be best, even at this late stage, to try and eliminate the reverse loop altogether but this will necessitate a major reworking which I am anxious to avoid.

Advice please?
 
dunnyrail

dunnyrail

DOGS, Garden Railways, Steam Trains, Jive Dancing,
25 Oct 2009
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St.Neots Cambridgeshire UK
You can use a Switch to Control the Reverse Loop.

The set you have relies on Diodes to change the +-. You drive a Train into the loop which needs the sections at each end, reverse the Controller and the Train keeps going the same way thus as you say meaning you can only go round it one way.

If you use a DPDT Switch you drive the Train inside the loop with Double Isolations each end. DPDT must be set for the end you drive into, stop the train change the DPDT reverse the Controller and drive train out still going the same way.

Schematic below shows how the DPDT is wired. Logic suggests that if you mount the Switch such that for a Train going into the loop the switch points that way or out of the loop that way you should have few issues with running.

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Though if you were to go DCC the LGB Reverse Loop DCC Box would do it all for you automatically. This link shows it in action though on a Triangle, the concept is similar.

 
Neil Robinson

Neil Robinson

Registered
24 Oct 2009
9,353
39
N W Leicestershire
When using analogue DC somewhere in the middle of the layout between the two red lines you will need to either always stop a train or only ever run in one direction.
Obviously the latter isn't an option with the siding! Is the distance between the Apple Tree Lumber siding turnout and the nearest red line long enough to hold the longest train likely to run over it?
 
T

twojags

Registered
26 Nov 2009
92
0
You can use a Switch to Control the Reverse Loop.

The set you have relies on Diodes to change the +-. You drive a Train into the loop which needs the sections at each end, reverse the Controller and the Train keeps going the same way thus as you say meaning you can only go round it one way.

If you use a DPDT Switch you drive the Train inside the loop with Double Isolations each end. DPDT must be set for the end you drive into, stop the train change the DPDT reverse the Controller and drive train out still going the same way.

Schematic below shows how the DPDT is wired. Logic suggests that if you mount the Switch such that for a Train going into the loop the switch points that way or out of the loop that way you should have few issues with running.

View attachment 255359

Though if you were to go DCC the LGB Reverse Loop DCC Box would do it all for you automatically. This link shows it in action though on a Triangle, the concept is similar.

Thank you for the helpful advice. Converting all my locos to DCC is likely to be beyond my purse at the moment even though I may have to go that route in the future. The research I have done so far suggests there is far more than simply connecting two wires to the track! I will investigate the Analogue DPDT solution first as I would have plenty of room for the longest train I envisage running on this section.
 
T

twojags

Registered
26 Nov 2009
92
0
When using analogue DC somewhere in the middle of the layout between the two red lines you will need to either always stop a train or only ever run in one direction.
Obviously the latter isn't an option with the siding! Is the distance between the Apple Tree Lumber siding turnout and the nearest red line long enough to hold the longest train likely to run over it?
Thanks Neil. There would certainly be room to accommodate the longest train I envisage running on this section of the track. but I am not clear as to how I might operate the siding if at all?
 
maxi-model

maxi-model

UK/US/ROW steam narrow gauge railways 1:1
27 Oct 2009
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146
Bucks/Oxon/Northants area
If you place your isolators at a point after passing the points to the siding and before where the red line on the left is and interpose a DPDT switch to control the polarity of the power fed into the isolated section then you will be able to use the siding. Just throw the DPDT switch to suit the direction you are travelling and the polarity required, either side of the isolated section, so you can pass. That's the way I do it on my turning Y. Max
 
dunnyrail

dunnyrail

DOGS, Garden Railways, Steam Trains, Jive Dancing,
25 Oct 2009
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St.Neots Cambridgeshire UK
If you fit your reverse loop Isolations as I have indicated below in Red you should be able to run the Circuit over the Bridge giving you 2 Circuits as I believe you would like.

The Isolation after you have just passed under the Bridge will give you some flexibility for Shunting Durango Wells.

The other Isolation on the line just to the left of the Bridge would allow access and shunting to the Lumber Mill on the Reverse Loop but this may problematical as I imagine there would be a Gradient to the Bridge here?

As for length of Train, so long as you do not have vehicles with connected metal wheels in the Train, the length using a DPDT would not be restricted by the distance between the two Isolations, though if you went DCC it would be.
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