Reversers

[Toolbelt]

Newby in the planning phases here. I understand the general rule is for the reversing section to be longer than the entire train passing over it, however, assuming only my loco is picking up track power at both ends, and my freight trucks are plastic (and won't conduct electricity between each pair per truck) and the metal Kadee wheels have plastic non-conducting axles, can I cheat a little? In theory, with my setup, could the reversing section just be slightly longer than my loco (assuming I won't be consisting)? I'm contemplating adding a short wing with a wye section to my 4 x 8 layout to enable reversing the direction of a loco. I've also read about staggering the track ends slightly (1/8"?) where the insulated joiners are installed. If I take the loco out of the equation, would a reverser section even be required if it only saw freight car duty only, provided the track has a pair of insulated joiners separating the two power phases?

 

[strobelight]

well, if it's a reversing loop, the engine would run into the back end of the train.

if the engine gets power from pickups on both trucks, as soon as one truck clears the insulated point you'd get a short.

for wye's, if all you're doing is reversing the engine, seems to me you'd be pushing the train unless there's a siding longer than the train so the engine can get to the other end, but I'm a newbie too, just thinking out loud.

 

[ctclibby]

Newby in the planning phases here. I understand the general rule is for the reversing section to be longer than the entire train passing over it, however, assuming only my loco is picking up track power at both ends, and my freight trucks are plastic (and won't conduct electricity between each pair per truck) and the metal Kadee wheels have plastic non-conducting axles, can I cheat a little? In theory, with my setup, could the reversing section just be slightly longer than my loco (assuming I won't be consisting)? I'm contemplating adding a short wing with a wye section to my 4 x 8 layout to enable reversing the direction of a loco. I've also read about staggering the track ends slightly (1/8"?) where the insulated joiners are installed. If I take the loco out of the equation, would a reverser section even be required if it only saw freight car duty only, provided the track has a pair of insulated joiners separating the two power phases?

Toolbelt: It is not about the plastic ( or metal for that matter ) between the two of the wheels on an axle. It is all about the metal of one wheel which touches ( shorts ) between the reversed and non-reversed section of that rail if the logic is backwards/inverted ( needs reversing ).

Staggering is a choice, doesn't matter to the reverser; which ever single wheel hits the reversing section first, it reverses the section if needed.

Taking the engine out of the equation does not change the fact of the single metal wheel rolling between the reversing and non-reversing sections. I guess that if those wheels are moving at a good clip the booster may stay operational when the quick short happens. What about if the wheel just happens to be sitting between the two sections? Booster shuts down to prevent max current and the wheel from melting.

Note: if it is a metal axle, one wheel is insulated from the other.

L8r

 

[timlange3]

It takes a non-zero length of time for the auto reverser to work. Depending on the loco speed it could go more than its length before polarity is switched.

 

[Toolbelt]

Toolbelt: It is not about the plastic ( or metal for that matter ) between the two of the wheels on an axle. It is all about the metal of one wheel which touches ( shorts ) between the reversed and non-reversed section of that rail if the logic is backwards/inverted ( needs reversing ).

Staggering is a choice, doesn't matter to the reverser; which ever single wheel hits the reversing section first, it reverses the section if needed.

Taking the engine out of the equation does not change the fact of the single metal wheel rolling between the reversing and non-reversing sections. I guess that if those wheels are moving at a good clip the booster may stay operational when the quick short happens. What about if the wheel just happens to be sitting between the two sections? Booster shuts down to prevent max current and the wheel from melting.

Note: if it is a metal axle, one wheel is insulated from the other.

L8r

I'm not sure what the tread-to-track surface contact area of a small HO wheel is, but it must be smaller than an insulated track joiner is? Are insulated joiners available with different gap sizes? Or is it more an issue of flange bridging? Would the nail polish method solve that?

 

[Toolbelt]

non-zero length of time

I heard it was measured in thousands of a second?

 

[jjames25]

I heard it was measured in thousands of a second?

How long does it take for electricity to go from the light switch to the bulb? Auto reversers are cheap and most have adjustments for speed of activation to guarantee cooperation with circuit breakers/protectors.
Back to your original question. I have two reversing sections on my layout which are much shorter than my typical train, I have no electrified rolling stock other than locos and have run this successfully for many moons.

 

[Toolbelt]

How long does it take for electricity to go from the light switch to the bulb? Auto reversers are cheap and most have adjustments for speed of activation to guarantee cooperation with circuit breakers/protectors.
Back to your original question. I have two reversing sections on my layout which are much shorter than my typical train, I have no electrified rolling stock other than locos and have run this successfully for many moons.

I was also thinking that, even if I had a lighted caboose, by the time it entered the reversing section, the loco would be back on the mainline, so it shouldn't be an issue. Totally different scenario if a lighted passenger train was being used, but I never intend on running longer cars on my tight-curve layout in any case. I'm just trying to avoid as many "oh crap" moments in the future as I can here.

 

[Toolbelt]

Lots of interesting info on this link, including some fairly deep reverser detail options. https://wiringfordcc.com/track_2.htm

 

[wright]

If the tail of the wye is not connected to anything else and that is the only reversing section on the layout, just make it the reversed section. You will need 4 insulated joiners. You could use an auto reverser or a DPDT switch to correct the polarity. You could be extra fancy and use a 4PDT switch and throw the switch with a stall motor switch machine and polarity at the same time. Technically, you could use the auxiliary contacts on the switch machine (Tortoise) but they sometimes burn out when switching track voltage.

 

[Toolbelt]

If the tail of the wye is not connected to anything else and that is the only reversing section on the layout, just make it the reversed section. You will need 4 insulated joiners. You could use an auto reverser or a DPDT switch to correct the polarity. You could be extra fancy and use a 4PDT switch and throw the switch with a stall motor switch machine and polarity at the same time. Technically, you could use the auxiliary contacts on the switch machine (Tortoise) but they sometimes burn out when switching track voltage.

I will likely go with an auto reverser. My plan is to use a curved turnout off my mainline down into 3-4 dead end ladders(? ) on my layout wing, with the thought of using the last turnout to drive forward back onto the main track, heading in the opposite direction of when I first exited the main. I suppose i could isolate all the wing track (ladders, switches) from where they leave, to where they return to the main line.

 

[Canalligator]

Technically, you could use the auxiliary contacts on the switch machine (Tortoise) but they sometimes burn out when switching track voltage.

I wired the second switch to a relay. That eliminates burning out the contacts in the switch machine. It’s been working flawlessly for six months now, I even forget that it’s a reversing loop.