Peco Small radius Wye (E197) wiring help?

[mogtrains]

Hi all.. tried searching for this and found the same question but not all of the answer :-)

I am building a small layout and using small radius peco electrofrog points (75). I've modified the first three 'straight' points by snipping the tiny isolating bridge jumpers on the back and adding new jumpers across the stock  - point rails.

However, got the small Wye and found that it is constructed differently..no jumpers to cut and the spaces for the new jumpers are closer to the frog. 

 

I'm getting the feeling that I'm going to have to cut the rails in order to isolate, and thus switch, the frog.. however I'm wondering if I can do anything with the wires on the reverse that come off the frog. (or maybe I need to cut these as well as cutting the rail?

 

Any help gratefully received! (except for 'don't use small wyes'.. It's a 'micro' layout and I'll only be running small 040 and 060 tanks - hence the fixes to improve the track power-wise.

[BR60103]

The small wye is a bit different that the other points. There is no prepared separation of the frog from the points. With the jumpers you have created a direct short from one outside rail to the other. It will be very tricky to cut gaps between the jumpers and the frog -- you can see where the wire is that links all the bits of the frog.

I think I just left mine as is and hope that the point-stock rail gap is large enough.

You could add a frog powering switch which would be redundant until the points stop making contact.

Edited February 23, 2019 by BR60103

[kevinlms]

I would cut through the closure rails, immediately above where you have soldered the jump wires & switch the from via a switch.

[mezzoman253]

I'd essentially agree with Kevin, but would have put the bonding wires one place down and cut the rails where you have the bonding wires now. then you are not too close to the frog itself.

 

Rob

[mogtrains]

Current progress. Testing with a battery and a bulb suggests it's worked. Unfortunately the cutting disc cut a little too deep.. however I think that will be disguised easily enough once laid.

[kevinlms]

Not exactly what I had in mind!

[ejstubbs]

I'd be a little concerned about the robustness of those wing rails alongside the frog vee.  I know that they are supported along the whole of the inner face but there are only two clips on the outside face.  However, if the cut in the wing rails had been made further towards the pivot with the closure rail then IMO that would have left the part with the pivot poorly supported.  I also think that a slitting disc is a bit of a clumsy tool to use for the job (which might be what kevinlms was hinting at).  A thin sawtooth disc might have made a neater job and cause less damage to the rest of the point.

AIUI, isolating the wing rails from the closure rails is primarily done to mitigate the risk of shorts between the frog and the wing rail.  If the frog and all the wing and closure rails are the same polarity (which Peco's under-the-sleepers wiring is specifically intended to achieve) then that risk shouldn't exist.  By adding jumper wires between the stock and closure rails you re-introduce that risk, which has to be mitigated some other way, typically by isolating the closure rails from the wing rails.

 

The Streamline short Y is a very compact point that doesn't have as much "real estate" to work with (rail clips/supports in particular) as the physically larger points in the range, even the sort radius left and right turnouts.  I suspect that Peco know that all too well (very likely from bitter experience) which is why the short Y, as supplied, doesn't have the gap between the wing rails and the closure rails - they know that it would weaken the point too much.

 

If you're happy that the stock (and especially the wheelsets that they are fitted with) are good enough to keep the short circuit risk to an acceptable minimum then you probably don't need to isolate the wing and closure rails.

 

If you are concerned about the reliability of the electrical contact between the stock and closure rails then, as BR60103 suggested, a solution that only switches the frog after the point blades have moved (eg some kind of delay timer before the frog switching is triggered?) might be the answer.

 

Again, as per BR60103, I don't bother with separate frog switching for my short Ys (of which I have...well, probably too many, but needs must when space is limited - and of course rule one applies...)

[mogtrains]

On 24/02/2019 at 12:08, ejstubbs said:

I'd be a little concerned about the robustness of those wing rails alongside the frog vee.  I know that they are supported along the whole of the inner face but there are only two clips on the outside face.  However, if the cut in the wing rails had been made further towards the pivot with the closure rail then IMO that would have left the part with the pivot poorly supported.  I also think that a slitting disc is a bit of a clumsy tool to use for the job (which might be what kevinlms was hinting at).  A thin sawtooth disc might have made a neater job and cause less damage to the rest of the point.

AIUI, isolating the wing rails from the closure rails is primarily done to mitigate the risk of shorts between the frog and the wing rail.  If the frog and all the wing and closure rails are the same polarity (which Peco's under-the-sleepers wiring is specifically intended to achieve) then that risk shouldn't exist.  By adding jumper wires between the stock and closure rails you re-introduce that risk, which has to be mitigated some other way, typically by isolating the closure rails from the wing rails.

 

The Streamline short Y is a very compact point that doesn't have as much "real estate" to work with (rail clips/supports in particular) as the physically larger points in the range, even the sort radius left and right turnouts.  I suspect that Peco know that all too well (very likely from bitter experience) which is why the short Y, as supplied, doesn't have the gap between the wing rails and the closure rails - they know that it would weaken the point too much.

 

If you're happy that the stock (and especially the wheelsets that they are fitted with) are good enough to keep the short circuit risk to an acceptable minimum then you probably don't need to isolate the wing and closure rails.

 

If you are concerned about the reliability of the electrical contact between the stock and closure rails then, as BR60103 suggested, a solution that only switches the frog after the point blades have moved (eg some kind of delay timer before the frog switching is triggered?) might be the answer.

 

Again, as per BR60103, I don't bother with separate frog switching for my short Ys (of which I have...well, probably too many, but needs must when space is limited - and of course rule one applies...)

 

Much appreciated. I suspect that this will be a 'learning event' for me! I will see how I get on with connectivity/shorts etc. 

 

(I used a thin sawtooth disc, made a first very neat cut and then on testing realised that I needed to go a smidge further to go through the rail.. that 'smidge' involved a slip, hence the gash!

 

I may order another as as a standby with no alterations in case this one has fallen victim to my bodgery!

 

[Nigelcliffe]

By cutting right on the knuckle of the rails, you've altered the geometry through the crossing area, which is a fairly critical part for smooth running.  Not where I'd have cut - I would be somewhere away from that knuckle no matter what else needed doing to support the cut rails. 

 

I'd have gone almost one sleeper towards the bridging wires and cut just before the sleeper.  You'd not loose any support as the number of chairs hasn't changed (its one better than you currently have, with the destroyed chair on the knuckle).  I'd have cut with a piercing saw blade, by hand, with the turnout suitably supported whilst cutting.    If any of the rails appear to move after cutting, then fix with some adhesive - I'd use a fairly free flowing epoxy, but some of the thicker super-glues may be adequate. 

 

- Nigel

 

[ejstubbs]

13 hours ago, Nigelcliffe said:

I'd have gone almost one sleeper towards the bridging wires and cut just before the sleeper.  You'd not loose any support as the number of chairs hasn't changed (its one better than you currently have, with the destroyed chair on the knuckle).

 

The OP also appears to have removed the factory-fitted jumper wires linking the wing rails to the frog - the cause of the short pointed out by BR60103.  Unless I'm very much mistaken, cutting where you suggest will then mean that he'll have a dead section of running rail ahead of the frog on each route through the turnout.  That would seem rather to negate the point of using electrofrogs in the first place - especially since the OP says he's only going to be using small tank engines so he probably wants all the live rail (of the correct polarity) that he can get under their wheels.

 

One of the factory-fitted jumper wires seems to be bonded to the rail underneath the sleeper you suggest cutting on the frog side of.  So, cutting where you suggest but leaving the out-of-the-box jumper wires in place will result in a dead short when the frog is switched the other way.  A possible solution to that would be to remove that jumper wire bond, cut away a bit of the plastic under the wing rail and re-bond the jumper there.  But that would seem to risk weakening the support under the wing rail that cutting the rail where you suggested was supposed to help with.  A bit of a no-win situation?

 

I think your suggestion has merit from a structural point of view, but it comes at the cost of creating potential electrical issues - which can then only be solved by compromising the structural integrity of the point in another way

 

There's really no getting away from the fact that the short Y is a very compact point (one of its attractions when space is tight) which offers very little wiggle room for the kind of modifications that are more easily accommodated on physically larger points.  Other solutions may thus be preferable - if they are actually required at all.  Arguably, on a 'small' layout, how much work is involved in making sure that the switch-stock rail contact points are kept clean enough for reliable power switching?  (I don't know enough about the risk of wheelset-induced shorts to be able to make any statement about whether they can or cannot be ignored - I note that the OP is using code 75, which may also be a factor to be taken in to account).

[Nigelcliffe]

1 hour ago, ejstubbs said:

 

The OP also appears to have removed the factory-fitted jumper wires linking the wing rails to the frog - the cause of the short pointed out by BR60103.  Unless I'm very much mistaken, cutting where you suggest will then mean that he'll have a dead section of running rail ahead of the frog on each route through the turnout.  That would seem rather to negate the point of using electrofrogs in the first place - especially since the OP says he's only going to be using small tank engines so he probably wants all the live rail (of the correct polarity) that he can get under their wheels.

 

 

Agreed,  with my cut, the two short bits of knuckle rail would need electrically connecting to the crossing (frog). 

 

 

- Nigel