DCC Electrofrog ladder crossings

[Kallaroonian]

 

I looked back and was literally  horrified to find I posted about this in 2010. Admittedly that was very extremely pre-emptive but even so..................

 

 

Anyway I am only now doing wiring. I need to up the priority on the layout or it won't be done before I'm gone if we're honest. The trackwork is all electrofrog using ADS8 accessory decoders and ECoS controller. 

 

I am struggling with frog polarity on a ladder with more than one exit point. I don't see how this is possible and worse I have a significantly more complicated ladder elsewhere on the layout. 

 

Look at the "straight" file attachment. 1 and 4 are LH turnout, 2 and 3 represent a single slip and there are two diamond crossings. The question remains, how to set the frog polarity. Note also that A and B are joined to the RH side not shown on the sketch. This means that when the ladder is in use its possible for a train to go 1 then 3 and 2 while theoretically at least another loco could be on track B and heading through point 4.

 

So with all roads straight one might set the ladder polarities using the entry points.  Then if you look at the "long" file this shows the polarities when the full length of the ladder is used. Again set by entry points now they have been thrown. In both cases I'll ignore the SS polarities because...

 

... we also have the configuration where the ladder is shorter and the loco enters at 1 but exits at 2 via the SS rather than going to 4 for the full length of the ladder per the "short" dia.

 

This is where it all falls apart. Looking at the "straight" diag then Slip point 2 and 3 are set straight and 2 needs to make the opposite polarity red while 3 needs to make its frog black. But in long ladder mode the slip points are still not thrown but the frog polarities need to be the other way around. Perhaps a solution is to set the slip frog polarities using the entry points and that works where we are considering the long ladder 

 

But when we look at the short ladder then a) both slip frogs need to be black and b) point 4 need to be set to straight since its not part of the ladder in the short configuration. 

 

I don't think this is do-able and the only solution must therefore be a frog juicer for the SS.

 

All thoughts welcome, thanks

 

mark

 

 

 

[Dagworth]

What point motors are you using and do they have built in polarity switches?

 

The slips are easy to wire if so, each point motor controls the polarity of the frog at the other end of that slip.

 

Andi

 

Edit: Sorry, I was thinking double slips not single. Single slips will need polarity tied up with the routes so yes frog juicers may be the answer

Edited January 1, 2023 by Dagworth

[Izzy]

The basic problem with a single slip is that while you can use the point motors to set the frog polarity both 'straight' routes cannot be set togther because you will get conflicting and opposite polarities for both routes. Some form of interlocking, or route setting as would occur with a double-slip is required to prevent this happening. So only one of them is set at a time. If this cannot be done then, as you say, using frog juicers is a simple alternative answer.

 

Bob

[Grovenor]

Points 1 & 2 should be operated together as a crossover, off one switch/lever, say 1.

Points 3 and 4 should be operated together as a crossover, off one switch/lever, say 4.

Then the interlocking required is 4 released by 1. ie you can only reverse crossover 3 & 4 if crossover 1 & 2 is reverse.

This can be simply achieved by using a 3 position switch.

Position 1, all point normal (Straight)

Position 2,  points 1& 2 reverse, points 3 & 4 normal

Position 3, all points reverse.

Point 1 will set polarity for frogs on 1 and the left side of the two diamonds, which will always switch to same polarity.

Point 2 will set polarity for frogs on the right side of the slip and the two diamonds, which will always switch to same polarity.

Point 3 will set polarity for the frog on the left of the slip and

point 4 will set polarity for the point 4 frog.

[newbryford]

7 hours ago, Izzy said:

The basic problem with a single slip is that while you can use the point motors to set the frog polarity both 'straight' routes cannot be set togther because you will get conflicting and opposite polarities for both routes. Some form of interlocking, or route setting as would occur with a double-slip is required to prevent this happening. So only one of them is set at a time. If this cannot be done then, as you say, using frog juicers is a simple alternative answer.

 

Bob

 

Agree - although "both straight" is mechanically valid for a single slip, it isn't electrically for frog polarity.

It needs to be operated as though it were a double slip.

 

If you set a single slip so both routes are straight - imagine if it had double slip blades - there would only now be one valid straight route.

 

Also - IIRC, the prototype railway works in a similar way.

 

There is a single slip not too far from me, combined with a trailing point that is used regularly. (Hourly as a crossover and daily as access to a siding.

They are interlocked so that "both straight" cannot be set.

This is a typical arrangement that was (and still is!) common on the Midland and Lancashire & Yorkshire Railway lines - as well as others.

 

 

[Kallaroonian]

 

Thanks for the feedback all, keep it coming :-)

 

Updates and responses :

 

The point motors are basic solenoids – Peco PL10.

 

The DCC accessory decoder is an ADS8sx; for anyone who is unaware this provides frog polarity switching and so it is this unit that provides this function rather than any mechanical switches attached to the motors. Control by ESU ECoS.

 

The possible routes across this network are :

-          Left to right independently for all tracks and vice versa. In reality as drawn the top two tracks are Up, the next two are Down and the bottom one through point 4 is a Down Relief/bypass whereby there is a turnout connecting A to B off picture to the right

-          Ladder from 1  to 4 (long ladder) and vice versa

-          Ladder from 1 to 2 (short ladder) and vice versa

 

The purpose of this ladder in RL must have been to get St Albans or Harpenden trains onto the KX Up line. The layout represents Hatfield Herts

 

Grovenor – thanks for those thoughts. I sketched this out again and initially thought it was still a problem.  However the trick is to have point 3 set to curved when all roads straight is required and point 2 set to curved when the long ladder is required.  This is counter-intuitive because you would expect both slips to be set straight when either all roads are straight or when the slip is used as a diamond to get to point 4.

However I believe this does solve the problem electrically.

 

The possible issue that remains is that with the DCC control I have no idea whether interlocking conditions are possible; I didn’t think they were? Certainly 1 and 2 can be operated together and the polarities arranged accordingly. Likewise 3 and 4.  The issue is keeping them mutually exclusive.

 

Do you know how that is done with ECoS? Is it solvable by establishing and using Routes?

 

Thank you so much for that input though because it will basically solve the problem I think.

 

He he he he…. that said it was kind of and hors d’oeuvres. Hatfield of the 50s ish being what it was, elsewhere I have the main ladder and another medium ladder which intersect.

 

The main one goes 3way-SS-SS-SS-SS-SS-DS-LXing-RH-SXing-DS-LH. You might argue it sort of finishes at the first DS. Or you might not.

And then the other one goes RH-DS-same SXing-DS-SS-DS-RH

 

Anyone fancy the challenge of thinking about all that? Or shall we all just say frog juicers together in unison?

[Kallaroonian]

Also, interestingly, it does mean I won't be using the ECoS single slip icon since the two halves will be operated separately and in conjunction with others points.

[ITG]

Why not specifically ask DCC Concepts (manufacturer of the ADS8) for their input? I’ve always found them very helpful, even when, as in this case, other manufacturers’ products are involved. A phone call or question on their own forum is usually responded to fairly quickly.

[Izzy]

10 hours ago, newbryford said:

 

Agree - although "both straight" is mechanically valid for a single slip, it isn't electrically for frog polarity.

It needs to be operated as though it were a double slip.

 

If you set a single slip so both routes are straight - imagine if it had double slip blades - there would only now be one valid straight route.

 

Also - IIRC, the prototype railway works in a similar way.

 

There is a single slip not too far from me, combined with a trailing point that is used regularly. (Hourly as a crossover and daily as access to a siding.

They are interlocked so that "both straight" cannot be set.

This is a typical arrangement that was (and still is!) common on the Midland and Lancashire & Yorkshire Railway lines - as well as others.

 

 

 

That is almost exactly how the track layout on my small 2FS layout Priory Road exists, except I added in the complication of an obtuse crossing and traps. This is why I suggested mechanical or electrical interlocking would be needed as I've been there with both .....  Being simple it took a while for the penny to drop that for electrical track power supply the S/S needed to be treated exactly the same as a D/S and then how to achieve that on a practical basis alongside the obtuse crossing polarities ......

 

 

1 hour ago, Kallaroonian said:

Also, interestingly, it does mean I won't be using the ECoS single slip icon since the two halves will be operated separately and in conjunction with others points.

 

Yes. Not quite sure how this could be set up using point control via DCC as I use hacked servos with a handheld switchbox with DPDT switches so which way they are thrown controls whether others work etc. Very simple electrical locking.  Route setting is probably the answer for your situation.

 

Bob

[Kallaroonian]

Yes I ad further thoughts this afternoon.  It will not be possible to drive two motors off one outlet unless their frog polarities are always to be the same. The problem is they aren't - when 1 is red, 2 is black; and when 3 is black 4 is red.

 

So the only solution here is to consider every switch as separate, arrange the polarities accordingly and then look at co-ordinating via ECoS Routes. I'm not sure if that will work or not but sounds promising

 

ITG - I have asked DCC Concepts actually. Just awaiting their return from break

 

No-one up for the mega ladder challenge?

 

 

[Grovenor]

I would always use a hard control panel or JMRI so can't really help with your ECoS. It does illustrate the problem of relying on commercial products designed for control of toy train pointwork and not allowing for models of real railways.

A standard crossover needing two sets of frog switches should be a normal provision in any design. But I would expect the ECoS to allow the two outputs of the decoder to be switched with one command, rather than trying to put two motors on one output.

If the ECoS has route setting then you just need 3 routes, all straight (normal), 1&2 reverse with 3 & 4 normal, and all reverse.

 

It helps when drawing the plans to show point in the normal position and where they form crossovers and work together label them as A and B. Here I've tried to show the frog switching as well.

Edited January 3, 2023 by Grovenor

[Phil Bullock]

We are discussing two seperate issues here.

 

Firstly interlocking. Speaking from experience Routes work well in ECoS and if set up logically will prevent conflicting moves.
 

And then Frog polarity… juicers are the easiest solution to the frog polarity issues with the polarity of each frog being determined by a train following the selected route.

 

HTH 

 

Phil

Edited January 3, 2023 by Phil Bullock

[Grovenor]

Juicers might be easiest but they are a lot more expensive than using the switching already built in to the decoder and/or point motor which Kallaroonian already has available.

 

[Kallaroonian]

Toy train pointwork is it? I think the ECoS is somewhat more advanced than that ;-)

 

I tried it today and the method worked. I haven't tried the route setting aspect yet but can't see how that would not address the issue fully. I did hit a snag in that one polarity of one of the frog switching functions didn't work hence a Cl08 test loco can only traverse that point in one orientation. Will raise with DCC Concepts but a bit of a worry as I have heaps more yet to install.

 

I have three other low grade epiphanies :

1. I thought I had ordered too few decoders because I based the use of SSlip on the idea that one output could drive both motors. Which is of course correct in principle

2. The complexity of the other ladders mentioned above is highly likely to make clever frog switching and allocation akin to the current works very difficult indeed. Given the preceding point also then I think frog juicers are going to be the solution

3. The other obvious use of one output driving two motors is a plain standard crossover. I can't see how this would be as convenient as people sometimes mention though - sure the ADS could drive two motors but the fog polarities are opposite so it would never be a solution

 

/sigh. I suppose tomorrow I swap out the ADS with the fault and wire another one in its place

 

cheers for the help, very helpful and much appreciated 

 

[Phil Bullock]

23 hours ago, Grovenor said:

Juicers might be easiest but they are a lot more expensive than using the switching already built in to the decoder and/or point motor which Kallaroonian already has available.

 

That may indeed be the case but I suggested them in the context that the OP was apparently struggling to align frog polarity with route setting. Using juicers separates the issues.

[55020]

Given that most DCC circuit breakers and Autoreversers do not react quick enough when using an ECoS, resulting in the ECoS short circuit protection kicking in, would there be a similar issue with using frog juicers given the basic functionality is the same?

 

 

Steve

[jpendle]

27 minutes ago, 55020 said:

Given that most DCC circuit breakers and Autoreversers do not react quick enough when using an ECoS, resulting in the ECoS short circuit protection kicking in, would there be a similar issue with using frog juicers given the basic functionality is the same?

 

 

Steve

Yes.

 

That's why you would need to use a solid state juicer such as the ones made by Tam Valley, rather than relay based ones such as the Digitrax offering.

 

Regards,

 

John P

[Phil Bullock]

15 minutes ago, jpendle said:

Yes.

 

That's why you would need to use a solid state juicer such as the ones made by Tam Valley, rather than relay based ones such as the Digitrax offering.

 

Regards,

 

John P

Spot on John … the Tam valley juicers worked brilliantly with ECoS on the old Abbotswood layout. 

[KingEdwardII]

20 hours ago, Kallaroonian said:

one output driving two motors is a plain standard crossover.

I do this with my DR4018 decoders and MTB MP1 motors - but there is 1 motor for each turnout in the crossover and each motor has its own switch for handling the frog polarity, so this is handled naturally for each turnout. So both turnouts operate at the same time using a single command to one channel on the DR4018.

 

Yours, Mike.