Peco Insulfrog Single Slip - not self-isolating?

[ejstubbs]

I've never used a slip of any kind before.  My current collection of track is code 100, and my layout plan requires a single slip, which must perforce be the insulfrog (SL-80) variety as they don't do an electrofrog one in Code 100.  I have no room in my plan for the Code 100 to Code 75 adaptor.

 

I've just been experimenting on an SL-80 with a multimeter and as far as I can tell it's not self-isolating like the ordinary turnouts are - every rail is always live, regardless of how the switch blades are set.  Is that correct?  I have read the Peco instruction leaflet but it's not completely clear on the matter IMO.  All it says is that the the Single and Double Slips are "already wired", whatever that is supposed to mean.  I get the next bit, about having to isolate the slip completely if you want to use it to cross two separate power sections.  That's not the issue in my case, but it does suggest that my findings are correct.

 

In my layout design, one leg of the slip is a siding.  I had naively assumed that the siding would be isolated if the switch blades were set so that there was no access to the siding from any of the other routes, but it appears that this is not the case.

 

So am I right to conclude that, if I want to stable a loco on that siding while another loco is running on one of the other roads emerging from the slip, then I will need to have a switched isolating section for that siding?

[caradoc]

Yes; The Peco single (and double) slip insulfrog points are not, and never have been, self isolating; Presumably due to the complexity of the items ?

[johnb]

Yes, I isolate the slip on all exits, make it a separate section all on it's own.

[ejstubbs]

Thanks both, that confirms my suspicions.

 

I don't intend to isolate the slip on all exits.  It's primarily there as a space-saver, to replace two toe-to-toe turnouts.  The divergent route from each turnout was isolated since it led to a separate power section.  Power for the section they were in was fed to the common toe between the two turnouts.  Looks like I can apply power for that section to the switched exit from the slip on the same section, and isolate it from the sections either side same as the turnouts were going to be.  I will have to add an isolating section for the siding where I want to stable the loco.

 

That might be simpler to explain with a couple of diagrams:

 

Toe-to-toe turnouts

 

Single slip

[kevinlms]

Yes, I isolate the slip on all exits, make it a separate section all on it's own.

No, best if switched by an accessory switch connected to one of the other points, with gaps all round. Drive it off one of the points, say the blue one in the later diagram posted by ejstubbs and make the slip a sub block of either the blue block or purple one, depending on point setting.

That makes it automatically connected to either track & does away with a switch. Its too short on its own to be useful.

 

Edit to add.

 

Yes, put an isolating switch to hold a loco in the short spur.

Edited May 1, 2017 by kevinlms

[DCB]

I would use isolators all round except one rail of the stub spur, treat it as a separate section and switch it from adjacent points through an accessory switch and relay or pair of accessory switches.  I drive 1 amp rated micro switches directly off point tie bars to change polarity in DC where the point is hand operated, obviously not an option for DCC as a 4 amp one is far too ugly.   The stub spur looks like it needs an isolator switch if you want to stable engines there.

Half the battle is understanding which way is "normal" and which point should control from which way the point is fed.  The arrangement looks a bit odd in that it is a facing crossover,  a mirror image trailing crossover would be more usual

[eastglosmog]

Just as a matter of interest, you don't have to use the Code100 to Code 75 adapter to change from one to the other, Peco do special rail joiners, (SL112), which will do the job without any intervening track.  I got some from Antics in Gloucester. They are insulating or conducting depending on whether you put the metal insert in.

 

[MickkyL]

I am not sure if I am missing something but I have just received my sl 80 and see the wiring diagram on the back. I plan on using servos to control my points but cannot understand where and how I attach the wires to the underside of the slip. Any help would be appreciated but as simple as possible please.

[MickkyL]

I am using dcc by the way.

[njee20]

Why a single slip, rather than double? Surely that compromises the available moves compared to the toe-to-toe turnouts?

[MickkyL]

Cant really answer that, I never gave a double slip a thought. I am not really familiar with railway type movements so sadly it may seem I am doing it as I go along. But no matter a single slip it is.

[njee20]

But you know that means trains cannot go from blue-purple in your diagram? As long as that's not a move you'll ever want to do, and all trains taking the diverging route on the blue end up on the green, then that's fine!

[friscopete]

I bought a" used" ,though  in fact brand new,Peco   code   75 double  slip insullfrog  for a  single point  price to try out  on my US code 83 and possible code 70  dead frog layout .Despite being dead frog it works fine with my  DCC /DC brass steam and plastic diesel switching layout .No isolating whichis  sad as I use a MRC Tech 6  which only runs one loco at a time and rely on isolating locos via points isolation.i will install a few switches to isolate the tracks but it all works well  . I use Woodland scenic underlay and foam cement so its eesy peezy to alter track layout .I though maybe i would need fancy point motors and wiring but it just lays there working and solving a track  layout problem .Pleased I didnt pay full price though .

[Hroth]

3 hours ago, njee20 said:

Why a single slip, rather than double? Surely that compromises the available moves compared to the toe-to-toe turnouts?

I bought a SL80 single slip because the prototype location uses one.

 

Its been sitting in the box for months as I'm completely flummoxed on how to wire it!

 

( Obviously a track element designed for "Expert" modellers )

[njee20]

I’ve just realised there are now 3 people asking questions. 

 

Clearly my comment was to the (rather old) OP.

 

That said which element are you both struggling to wire? Where to put feeds, or polarity switching?

[DCB]

It might be easier to change to a Double slip   A Double slip is much easier to wire than a single slip or indeed a live frog diamond, It just needs two wires to the bus from half way along the outside rails and isolators on every rail joint.  I use a four pole changeover relay operated by a point motor switch for route selection on live frog diamonds so the difference in wiring/ hassle is immense.

[ejstubbs]

On 11/07/2019 at 21:27, njee20 said:

I’ve just realised there are now 3 people asking questions. 

 

Clearly my comment was to the (rather old) OP.

 

In which case: duh, yes I do know the difference between a single and a double slip.

 

As you say, I started the thread over two years ago.  I have worked out how to wire it in the intervening years.

[newbryford]

On 21/07/2019 at 11:51, DavidCBroad said:

It might be easier to change to a Double slip   A Double slip is much easier to wire than a single slip or indeed a live frog diamond, It just needs two wires to the bus from half way along the outside rails and isolators on every rail joint.  I use a four pole changeover relay operated by a point motor switch for route selection on live frog diamonds so the difference in wiring/ hassle is immense.

 

Not much use when as mentioned by one poster above that the prototype uses it.

There is no difference in wiring a double or single slip - the motor/switch feeds the opposite frog - simples.

 

It's how you use a single slip that causes problems.

 

A single slip and point used as a combined crossover and access to sidings was/is a very common way of doing things to avoid facing point blades on the main line. Virtually every station on the Settle-Carlisle route used such an arrangement. Other Midland routes and the L&Y were also common users.

There are many such configurations still in use today.  Peak Forest Jn and Horrocksford Jn are two examples that I am quite familiar with that still operate this way daily.

 

Train is on the down line and passes over the slip, then stops. The prototype will change one half of the single slip and the point to make the crossover.

Train reverses from down line to up line over the crossover.

Then once crossed over, the other half of the slip will be moved to allow access to the sidings.

Train goes forward from up line - across the slip and down line  - into the sidings.

 

If  the frogs are wired as one motor on the slip powers the opposite end frog, and the points are operated as above, then there will be no problem whatsoever.

 

 

 

Edited July 28, 2019 by newbryford