Must be lightly used

[MD2020]

LOL ! :)

I recognize "Harmon" there. LOL :)

Trying to remember the electronic systems names maybe over the next week or so
they'll come back to me.

AFO Audio Frequency Overlay with its cables tacked down to the ties to form a loop,
kinda like the automobile traffic signals use. I always got a kick out of that one for
some reason. :)

Marquart's (right?) Predictors and Motion Sensors. I didn't like Predictors because
they were all the time messing-up and leaving the gates down. Dangerous, that!

There was an ATAK(?) that used a diode that didn't short out the track circuit but
would transmit half the AC signal.

I was always more interested in the mechanisms and relays and that sort of stuff
and especially the train signal systems and not so much into the crossing stuff. ;)

Oh heck, gotta go. TTYL

AlvininAZ

Well, not exactly. An "AFO" does not use inductive loops. AFO (Audio Frequency Overlay) is used over an existing track circuit. It is transmits and receives over the rails just like other track circuits. Also, an "AFTAC" is not an AC/DC track circuit, it is an "Audio Frequency Train Activated Circuit" system, much like an AFO. You may be thinking of an SCX-1, which is an AC/DC system that combines 2 approaches and an island into an integrated control unit.

Just factual FYI.

[AlvinAZ]

Also, an "AFTAC" is not an AC/DC track circuit, it is an "Audio Frequency Train
Activated Circuit" system, much like an AFO. You may be thinking of an SCX-1,
which is an AC/DC system that combines 2 approaches and an island into an
integrated control unit.
Just factual FYI.

Cool. :)

I told you I wasn't into electronic crossing stuff. ;)

Relay logic circuits and DX-13s were fine for crossing bells, it's when them stinkin'
gates came along, then the electronic stuff was needed. YMMV on all that? LOL :)

Well, not exactly. An "AFO" does not use inductive loops. AFO (Audio Frequency
Overlay) is used over an existing track circuit. It is transmits and receives over the
rails just like other track circuits.

Yeah, but. ;)

They used the same name-and-initials for their new system that didn't use the
cable but the older system used the loop of multi-conductor cable and it was also
called AFO. No kidding. :) Many of them were used with Electric Locks and they
outlasted those that had been used for crossings.

Alvin in AZ

[MD2020]

Are you sure that system you're thinking about was an AFO? AFO's have been around for a really long time. I have some AFO transmitters and receivers that Julie Johnson had sent me that were from the 60's. Could you be getting the letters confused? I'd like to see what this system you speak of is. I actually have almost every type of train detection device used for grade crossings, with the exception of some of the older short lived stuff, and the really new stuff.

Here is exactly what a US&S AFO is: http://gsee.sdf-us.org/signals/docs/pdf ... s_6414.pdf

This is an example of a (modern) inductive loop track circuit as you speak of: http://railroadcontrols.com/products/In ... ochure.pdf

-Not impressed with RCL in the slightest, by the way. I have never seen such poor planning and quality of materials and installation with crossing installations on such a broad level before.

[AlvinAZ]

Here is exactly what a US&S AFO is:
http://gsee.sdf-us.org/signals/docs/pdf ... s_6414.pdf

...(modern) inductive loop track circuit...

I need to look through my old books and see if I can find a book on the old AFOs for
us, it'd be cool to turn it into a PDF but I'll have to learn how to make PDF's first tho. ;)

Check it out, the earliest revision is 1988 on that AFO's book.
That's about the time the new style AFO came out that didn't have the cable. :)

The cable loop was between the rails and on top of the ties on the old AFO and the
cable's wires were cut and sliced onto another wire so the electrical path went round
and round. I never installed one so don't remember how many conductor the cable
was. :/

Only trouble I ever had with them was from lightening striking and running up the
rail and that was just a couple times. The rest of the time they worked good for me.
Guys in the office complained they weren't reliable and that always made me wonder
if they weren't being blamed for trouble that wasn't their fault by the other signal
maintainers.

Alvin in AZ

[MD2020]

AFO's (Audio Frequency Overlay) circuits (True AFO's, = Track based) have been around since the 60's. Rather old technology. I have several units that are 1960's and 1970's era.

I am interested in anything you can show me that has an AFO that doesn't require a track circuit. (Inductive)