Cincinnati Metropolitan Area Sirens

[Chriswg]

Now a question for you. I've noticed some people refer to Cincinnati's T-bolts are being 'reverse wired' and 'don't pack as much punch as a result'. Can anyone elaborate?

Having trawled through some videos I note some sound more like a 2001 and there are others which of course have that Thunderbolt sound.

Can someone educate me as to what causes the difference in sound on these?

[Stormsetter4]

Now a question for you. I've noticed some people refer to Cincinnati's T-bolts are being 'reverse wired' and 'don't pack as much punch as a result'. Can anyone elaborate?

Having trawled through some videos I note some sound more like a 2001 and there are others which of course have that Thunderbolt sound.

Can someone educate me as to what causes the difference in sound on these?

Normally, when a Thunderbolt is correctly hooked up, the air is pulled in from the blower cabinet, into the top of the roots blower and then out the pipe on the bottom, then up to the head. When two of the three phases get switched (Like when a building gets a new electrical service, most common cause)
it reverses the blower, and instead pulls air in through the siren horn, down the standpipe and out the top of the blower. This causes a large loss of sound output and creates a vacuum inside the chopper motor, thus making the siren have a longer wind-up and wind-down, and it also significantly raises the pitch of the siren.

Examples:

Normal Thunderbolt, same Chopper tap (5)


https://www.youtube.com/watch?v=YVmK4_FLhjY

Reversed Thunderbolt, same Chopper tap (5)


https://www.youtube.com/watch?v=05U4jjZYGzk

Hope this helps.

[Chriswg]

I see where you are coming from. I was concerned that the 'reverse wiring' was in actual fact something like the polarity being reversed on the motor itself.

However in regard to the different tone see this video - it sounds nothing like a T-Bolt.

https://www.youtube.com/watch?v=j--kCHqKpsg

[Chriswg]

Ah problem solved - It appears to be the difference between a 1000 and 1000T. Is there a quick way to tell the difference other than pulling the chopper apart?

[coastalsyrolover]

Also note though, just because a thunderbolt is high pitched doesn't mean it has a reverse wired blower. The thunderbolts motor does have adjustable speed thus making the pitch higher or lower depending on how you set it. But yes usually if the bower is reverse wired, it ends up sounding like a screaming weasel.

[Chriswg]

I gotcha now!

Well I'm looking at obtaining from Cincinnati next week at some stage for this project. Would prefer a dual tone - Can anyone advise of a location for one? I have free choice of the surplus range and obviously won't be able to test their functionality.

Whilst it doesn't particularly matter is there a visual way to determine whether it is a single or three phase siren just by looking? (Other than via a plate).

[coastalsyrolover]

I gotcha now!

Well I'm looking at obtaining from Cincinnati next week at some stage for this project. Would prefer a dual tone - Can anyone advise of a location for one? I have free choice of the surplus range and obviously won't be able to test their functionality.

Whilst it doesn't particularly matter is there a visual way to determine whether it is a single or three phase siren just by looking? (Other than via a plate).

Without removing parts? (Side paneling, the panel on the RCM, the plate on the siren) not really... But looking at the plate there is a pretty simple way to tell... I'm on my phone and can't slap a picture of the plate up so maybe someone can slap one up for more visual detail... Telling if it's a single or dual tone... Only way I know how to do that is run it up or look at the chopper which you can do by taking the horn off. Be careful of course not to stick your fingers in the port with the chopper moving.

[Stormsetter4]

Just bump the chopper a little bit if it's still hooked up, that's the easiest way to tell.

[Hannah]

if there on the ground and disassembled i would look in the chopper port on the chopper cap , if the horn is still on it shine a light down the throat of the horn. if you can visually see in the chopper slot look to see if it doesnt have a dividend in the magnesium chopper assembly, if not and it has a large port then its single tone. if it has a dividend in the chopper it self and two seperate ports then its a duel tone. Like everyone else said if its still assembled and on a pole and still hooked to power bump the chopper just a bit in the rcm panel to see if it is single or duel tone.

these are pictures from my collection of some 3 phase siren stuff that came from around the cincinnati area and what you might run into.
here is what a mid 1950's 3 phase RCM panel looks like..



here is what a 3 phase 1950s A1 blower with 3 phase motor looks like


here is what a 1960s 5m blower with 3 phase motor looks like, blower needs to be degreased and not sure of motor brand.

[Chriswg]

Is Cincinnati's system typically dual or single tone?