Oklahoma City's Whelen System Curiosity

[Brendan Ahern]

You are halfway right about the home position on whelens. If you run the sirens in any tone, they will stop wherever they are facing when they shut down. When you use the SI-Test feature, they will return to a home position after the test. This is because there are 2 trip switches on the rotator. It will rotate clockwise, hit the trip switch and stop, then turn counterclockwise, hit the trip switch and rotate the other way again. This is how they operate and this is how the Si-Test feature tests for rotation. Whelens with voice capability will always face north after a SI-Test, or whenever someone at the controller calls for the sirens to return to a home position. As for 2001's, I dont think they have a home position, as it wouldnt matter much for that type of siren. It could just be coincidence, I have seen 2001's stop in the exact same position before, just a matter of chance I guess. Even during weekly silent testing, the 2001's are always facing a different direction.

[woodyrr]

I was driving around Lake Draper this afternoon and I saw one of OKC's Vortexes turning. At first, I thought they were conducting a silent test, although the normal daily test is at 9:00 AM. This siren is located in an area that experienced either very high winds or a tornado a couple of weeks ago. It became apparent that it was actually twisting freely on its rotator in relatively light winds. I've seen OKC's Vortexes in high winds before and I've never seen one twisting. I'll wager that this one's rotator was broken by the high wind load that day.