Answers 1 and 2
Hi Brian,
- A Set Track turnout is an Insulfrog turnout, just with a tighter radius and a different track geometry. It behaves electrically like an Insulfrog turnout. Provided you follow the installation instructions with either plastic railjoiners or an isolating cut on BOTH rails heading away from the frog, then you should have no problems with wheels electrically bridging the frog area. See NO FROG SURGERY REQUIRED below, copied but modified from elsewhere on here. This applies to BOTH DCC or non-DCC usage.
- That turnout in the photo is a Fleischmann Profi-track turnout with "plastic ballast" pre-installed. The black clips effectively "hot wire" the blades and convert the turnout to a non-route selective turnout. With those clips removed the turnout becomes route-selective with the non-selected route being electrically dead downstream of the blade. See the diagram at the top of the second page at https://www.fleischmann.de/doc/an/2/de/BA_6170_200911.pdf
No frog surgery or modification required
The Peco wiring instructions for Insulfrog turnouts included with the turnouts were available online at https://www.peco-uk.com/imageselector/Files/Instruction%20sheets/HO-OO%20Insulfrog%20Turnouts.pdf but it looks like the Peco website is being re-worked and this link is no longer valid.
The reason for the variation in insulating block width is that Peco changed their Insulfrog design some years ago to reduce the amount of insulated track in their turnouts. This was done to improve running characteristics for short wheelbase 0-4-0 and 0-6-0 steam locomotives more commonly used in the UK. Any turnouts with the larger insulating block and plastic frogs are of the oldest design.
The bold emphasis is mine, but the key point from the Peco instruction sheet is
Quote:
Turnouts and Crossings since they are electrically self-isolating and ready for use. However, some incorrectly shaped metal wheels can cause a short-circuit when crossing an Insulfrog due to the wide tread of the wheel touching both frog rails at the same time. This occurs when a back feed takes place in a continuous loop. To overcome it insert a Peco Insulating Rail Joiner next to the frog rail of the track forming the loop (3). The golden rule of two-rail electrification is to ensure that current is fed to the track from the toe end of any turnout(s).
If you have the track down and ballasted already, then the option of using the insulating rail joiners is off the table. But you can replicate this by gapping the track on the two frog rails away from the frog area. This is a far easier fix than "frog surgery". It also has the advantage that it is done on straight rail and can be done far enough away from the frog that you don't have to worry about your thin Dremel cut-off wheel snagging an adjacent rail by accident while cutting.
It doesn't matter whether you are running DCC or DC. As shown in the photo below, gapping these 2 rails ensures that you can't have a short-circuit path in the frog area.
How this works:
Peco Insuffrog turnouts ONLY power the route the turnout is set for. The other track is electrically dead if the turnout is fed from the toe of the turnout. If something gets across the insulation pieces then frog rail on the other route feeds via the wheel and you get a short circuit. The other route frog rail is being powered by the feeders on that other route NOT by the turnout. This is where the short-circuit occurs. By gapping both frog rails you ensure that the other route cannot backfeed the frog area from the route that is not set.. It doesn't matter if both frog rails are different "polarity" while wheels bridge the insulating pieces, because there is no current path across the track gap to short circuit on the 'wrong rail" on the other route. On the route that is not set there is also nothing to bridge across that track gap.If both frog rails are gapped and you have correctly wired feeders.
For the route that is set:
- power through the turnout up to the frog gap cut is being provided by feeders at the toe of the turnout and the turnout blade itself
- power beyond the frog gap cut is being provided by under-track feeders
- power to the frog area to the other route is isolated at the turnout frog by the Insulfrog design.
- power to the frog area from the track feeders on the route that is not set is isolated by the gap in the frog rail for the route that is not set.
With properly coned wheels it should be impossible to bridge over the insulating blocks as designed. BUT some larger steam locomotives and some early smaller fixed-wheelbase diesels had "blind drivers" that had a flat profile and were fitted with un-flanged wheels. This allowed these intermediate wheels to handle tight curves by sliding sideways on the railhead without having to provide sideways slop in drive-rods and axlebox bearings of a model that were in the prototype design. Blind drivers are also a trick that some manufacturers have used that allows us to bend our model trains around scale-dimensioned curves many times tighter than than the prototype was designed to handle. Please check that your most persistent "culprits" are not fitted fitted with blind drivers. Even if they are so fitted, gapping the frog rails at each turnout should fix the shorting problem, as shown below in the red boxes. Those nickel-silver track joiners should be isolating track joiners. Then there is no reason to do any frog modification.
But to be really sure, you might like to move the location of the missing isolation gaps shown in the above photos to a distance from the frog that is longer that the length of your longest locomotive. This ensures that any single electrically conductive locomotive unit or wagon cannot bridge across the insulation..It also make sure that only 2 axles of any really short-wheelbase locomotive can be isolated at once and reduces the chances of a short wheelbase loco stalling near the frog area.(Note: stalling is a different problem that needs to be addressed differently than any short circuit problems)
If you want to make both blades simultaneously electrically live by "hot-wiring the blades under the turnout, then isolate all 4 rails heading away from the turnout. Just like you would have to do on an all-metal hand-laid turnout. for both DC or DCC to prevent shorting at the turnout..
Later Additional comment - the current design of the frog area minimises the dead area of the Insulfrog (both Set-Track and Streamline) turnout to maximise a locomotive's electrical performance when passing through the turnout. The requirement to isolate both frog rails to prevent electrical shorting is far easier to achieve than the requirement to install additional switches to switch the frog polarity on any live-frog turnout. Either 2 plastic rail joiners or 2 small cuts with a razor saw or thin Dremel cut-off wheel will fix your problems with no modifications to the frog area being required.
That ought to do for this post.
