It's been covered before but here's the catalog page:

http://www.jmarcoz.com/sirens/sc7.pdf

This is from Wikipedia: (Sometimes not the best source of info) After the 1941 attack on Pearl Harbor, concerns surfaced that the American public should be notified in the event of air attacks. The United States Department of the Army granted the company a contract to manufacture outdoor warning si...

The first two Mobil Directos were made in October 1942 and tested around the city of Milwaukee. It was not until 1944 did Biersach & Niedermeyer Co. get permission from the OCD to produce more sirens. The Milwaukee Mobil Directos were not permanently installed until 1951-1952. There are many arc...

Could the mystery 30 HP siren be a rebranded ACA Hurricane?

Yes, it was a Hurricane.

It doesn't explain how it projects the sounds above people that are 400 feet or closer, though.

Their job was not to explain how the product works but to sell it to you.

Always good to have fun on the job.

That is an Erick siren. Erick sirens have the legs fastened onto the bottom of the motor and the shroud paneling is mesh screen like a window. The siren head is always directly coupled to the motor. There used to be several of these Erick sirens across Minnesota and much of the Midwest in the past. ...

Going through the Wisconsin section for sake of perspective... 1. Fond du Lac had 3 Thunderbolts at the time, with others being added later on. 2. Clintonville was only using a Thunderbolt 1000 at the time because their famous Red Arrow Model 12 got plastered by lightning and was down for a while be...

Short intakes and lack of valve covers reveal a two signal Soundmaster core. The two Soundmasters in Henry and Cottage Grove were from Wisconsin and were refurbished years ago. They did not come with discs so each town decided to do what they could. The other one in Henry is mounted horizontally - n...

Interesting... didn't know that. Is it true that these are really as loud as a T-128 facing you? I see that all the time in youtube comments but that seems kind of unlikely. I wonder if this is still active. It isn't anywhere near me so I can't record it anytime soon. The Red Arrows are very loud s...

This is a 2 horsepower Decot Engineering Works siren. It is smaller than the 3 horsepower (Monessan, PA) and 5 horsepower (Seattle, WA). The one brochure I've seen from this company goes back and forth calling it a 'Two Tone Siren' and simply a 'Decot Siren'. It is most likely 10-15 ports which was ...