Step-by-Step Telephone Switch Line Finder HD

Some various short video clips from a Western Electric Strowger telephone switch from a telephone office. I'm working on a video of my switch, and thought I'd upload a few sample clips.

Category:

Science & Technology

Tags:

• telephone
• strowger

[darrellw82]

Are these connecting actual calls or connecting the numbers that someone would being using like in a rotary phone?

[westernelectric]

@darrellw82, this is connecting the numbers that would be dialed using a rotary phone. For this video, I used a modern computer to simulate calls (it generated the dial pulses that would normally be created by a rotary dial). But, there are several rotary phones connected to it that can be used to call one another.

[HappyDiscoDeath]

@westernelectric what software do you use to generate the pulses?

[westernelectric]

@HappyDiscoDeath For the portion of the video that has multiple calls being processed at once, I'm using the open source PBX Asterisk to generate the calls. When it's a single call, it's just a plain old rotary telephone.

[andyvalve100]

Great! How did you get it to behave like that? Are you using a routine tester?

I notice that at 0:48 the vertical wiper rotates, is that normal on US strowger is is it simply that it is trapped by the wiper cords? On UK strowger the vertical wiper is double sided and remains in contact as the shaft rotates.

[westernelectric]

The Line Group has a built in test function that sends each Line Finder to the top level and last position.

The vertical wiper is designed to rotate off of it's contacts when the switch rotates. It's only used to find the level requesting service. I know that this is standard behavior for Western Electric switches. I'm not that familiar with others.

[dan2kxyz]

Thanks a lot for posting this!

[MarcF444]

Yes, it has to perform mechanical processing for every digit dialed during a call.

[MrJivePirate]

@sixxstringsteeeve Would one of these machines have to work for every call made? Thanks.

[sixxstringsteeeve]

This takes me back....I used to maintain a couple of these with my father in a couple of schools in california.

It was great that I was able to find footage of a working step by step.

Thanks for sharing.

[Arabhacks]

Yes, a line finder would normally hunt for a vacant pair and stop.

If one could not find one from the first layer it would go up one and try again, 1000 attempts, before dropping out,

So it should be a click, than ten clicks, drop and two clicks, and ten clicks, etc.

Several companies produced a unit that gave most of the features of an ESS office to a step office.

This was done by placing the line finder under electronic control.

In that case you would have heard a faster buzz only.

[MarcF444]

@Arabhacks, I'm guessing you're referring to the Line Finders at the beginning of the video. They are running a test that steps them to the top level then to the 10th position then hits the release magnet. They wouldn't do that in normal call processing.

At one point in the video you can see multiple calls being handled at once. Those calls are being generated by an Asterisk switch. That Asterisk switch actually allows this mechanical switch to talk to others. Check out ckts.info .

[Arabhacks]

Why is it that the step selectors promptly drop out?

A call placed should select another and another.

And, although I do agree that electromechanical switches have charm, the Asterisk switch can handle hundreds of calls in the time that the stepper can handle 2 digits and in the same space.

[usrkzh]

This is an old Western Electric 355A type allotter linefinder group. I think used also in WE35E97 additions.

[kiwipreacher]

My father worked in our local telephone exchange. I sometimes used to viist him at work aftrer school in the early 70s and spend ages mesmerised by the selectors.

[Xerox6085I]

@westernelectric ...and just think, all the ESS equipment has to be in Air Conditioned rooms whereas before the old mechanical switching did not require it. You wonder why it cost's so much to operate this equipment these days?