if I cut gaps in the rails (HO) for any of the usual reasons, will metal wheels short the gaps? I realize I could fill the gaps with something non-conductive, but is that necessary? It seems like it would be, but I've never seen it mentioned.
- Harry
Other then cutting gaps in the rails for expansion purposes I can't see any viable reason for doing it. If your looking to isolate a siding lets say then I would use insulated rail joiners and make the power to the siding selectable.by this I mean put a small spst toggle in line with one of the track feeders, allowing you to kill the power to that particular siding. It's been suggested here by some that it's a good practice to do that in a yard situation which I haven't done but can understand why some think that way but I have since done it to all my sidings so I can have a locomotive parked there and not be concerned with it.
What your describing by the wheels bridging the gap cut in the rail is not shorting per say but completing the connection
I use Peco electrofrog turnouts. I have to have gaps in my rails at all my switch point ends of my turnouts, or I will have shorts when switching tracks. I understand your question about the metal wheels bridging the gap. I use a DCC system and run metal wheels and use nothing to insulate the gaps. even at slow speeds I have never had a problem. Your question makes me want to go to the garage and bridge a wheel right on the gap and see what happens. I hope someone has a good answer about this I am realy curios now.
Truck.
Thanks, guys.
Truck, I hope you have time to try it. I'm sort of a newbie in the design phase of a layout, and all help is appreciated.
Well I did it. If I bridge the both rails on one track nothing happens But if I bridge the gaps on the track next to the first one while it is still bridged, even one rail. DCC system shut down. But this could never happen while my trains are running, because all of my gaps are close to the point sides of the turnouts. The trains would run in to each other before they could bridge all the gaps at the same time.
Sure, metal wheels will "short" the two rails when they bridge the gap. Anything with track pickups will short the two rails
The gap is to keep the two rails from shorting to each other when they are not the same polarity(DC), phase (DCC). With a switch, that electrofrog can be matched to either rail's polarity. That depends on which way the points are thrown. Since the frog can be either polarity, the two rails that are attached to the frog have to be isolated from it with a gap. Now, if you are going through the route that the switch is set for, there will be no short as the wheels will be connecting two matched rails. If you try to enter the switch from the track that it is not set for, you will get a short circuit, the circuit breaker should trip.
The key to your test is that the booster's breaker did not trip until you intentionally shorted the gap by rolling a wheel across it. Without the gap and resulting short circuit, your booster would never even power up.
Metal wheels will not short the track at the rail gap unless the two rails are of opposite polarity (or phase, in the case of DCC).
If you have everything wired correctly, this should not happen.
This issue is well known and mentioned a lot and goes back many years. Many miss this issue in articles.
Use rail insulators or stick some styrene in the gap with CA. File smooth. If you have a layout on Homasote and have large variations in temperature and humidity, it can be an issue.
In our club, we have that issue.
Switching to DCC, we had to cut gaps with a thin Dremel cutoff wheel. Many places we did not use anything to fill the gap as the gap is quite narrow.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
Rail gaps are needed for a couple of different purposes. One would be on the frog end of an electro frog type turnout where the frog and the rails beyond it are live. If no gap was provided, the track power would short when the route was changed. Another would be to divide a layout into blocks or power districts. Another would be to isolate sidings so they are not powered all the time.
There are two ways for making insulated gaps. One is to use insulated rail joiners when laying your track. The other is to cut a gap after the track is down by using a cutoff disk in a motor tool. If you use the cutoff disk, you don't necessarily need to put an insulated piece of plastic in the gap, but if you don't, the cut rails may expand enough to touch again. If they touch and short the track power out, it may be hard to find.
Now having said that, I use insulated rail joiners if I can find ones that are not overly large. And still sometimes I miss installing some. So I cut them with a cutoff disk. AND, I don't put in a bit of plastic to keep them apart. But that is just me, and I have been in the electronics field for more years than I care to remember and can find the shorts easily when they occur.
Elmer.
The above is my opinion, from an active and experienced Model Railroader in N scale and HO since 1961.
(Modeling Freelance, Eastern US, HO scale, in 1962, with NCE DCC for locomotive control and a stand alone LocoNet for block detection and signals.) http://waynes-trains.com/ at home, and N scale at the Club.
Thanks for the help guys.