The Siren Board

Posted: **Sun Apr 13, 2008 2:39 am**

The air density play a role in the windown and the sound output i believe.

Posted: **Sun Apr 13, 2008 2:41 am**

What!? I thought you never ran power to it.

Posted: **Mon Apr 14, 2008 12:16 am**

Robert Gift wrote:Beautiful Q, Henry.
Was it ever used on a vehicle?

Thanks, also for the different rotors displayed.

The Q rotor is a work of art, too.

Interesting that they "growled" at higher vehicle speeds.
I never noticed ours do that.

Their published inrush and maintenence amps are too conveniently even numbers.
Would like to know the REAL values.

This one did come off one of our units in the early 70's. I had it re-chromed around 1980 and besides some periodic polishing, its held up well through the years.
Free wheeling of the rotors at speed was not uncommon in those days. Not sure if it was because of the ball and ramp clutch. Federal now uses a different type of clutch. In fact that is one reason that B & M manufactures its present day coasters with a brake that is normally on. In other words you apply power to the brake to retract it from the back of the rotor. Our leader did not believe in brakes on any of our coasters which included Fed. model 77's, C5A's, Q's and B & M CS8's, He claimed it was too hard on the coaster bearing, not sure if there was any truth to that.
If any body is interested, those rotors are from a Fed. Model 28, Sterling M30, Fed. Model 77 and of course the Q.
Here is a different pic of the rotors:

Posted: **Mon Apr 14, 2008 12:53 am**

Henry455 wrote: If any body is interested, those rotors are from a Fed. Model 28, Sterling M30, Fed. Model 77 and of course the Q.
Here is a different pic of the rotors:

Neat a sterling M30! Do you have the rest of the siren?

Posted: **Mon Apr 14, 2008 3:25 pm**

Yes, its one Hoss of a siren, large motor and heavy. Its called a "free rolling" M30 but is not a coaster, no clutch.

Posted: **Mon Apr 14, 2008 6:49 pm**

Sterling 30s are my favorite fire truck siren, because they were the first ones I heard on a truck I rode on. The pitch was very clean, a little lower than a Q, and just as loud, at least it seemed it was. This is the siren I wish someone would sample for an electronic version.

Posted: **Thu Apr 17, 2008 7:58 am**

Thanks for the interesting views, Henry.

So, do the sirens whose brakes engage when powered off spin down faster?
I wouldn't like that at all.
I want natural spinning down.
If the Q were direct-coupled to its motor shaft, would it slow noticeably faster?

Years ago, I spoke with someone at Federal about making Q sirens with half the ports so they would speak an octave lower.
They thought it an interesting idea.

I wonder what % sound output is reduced by all those stator protective ribs.
If I had a siren like that, I'd remove them and file the ribs smooth with the stator port edges.

On the M30 above, is there a sound quality difference if you remove the front cowling?
Would it not be.tter if exponentially flared intake?

Posted: **Thu Apr 17, 2008 2:20 pm**

The sirens with normally "on" brakes are wired so the brake is released when the siren arming switch (allows power to the siren relay/solenoid) or the emengency lighting switch is activated. Thus the brake retracts from the rotor and stays retracted until the arming switch or the emergency lighting is turned off. The brake is not wired to the siren motor circuit so the rotor will coast when power is switched off by the foot switch/horn ring/or push button. Here is suggested wiring diagrams from B & M.
B & M wiring diagrams

I do not have an answer regarding the M30 intake, I plan on recording all of my sirens in the near future and will see if removing the intake makes any difference.

Posted: **Thu Apr 17, 2008 2:33 pm**

Henry455 wrote:... Thus the brake retracts from the rotor and stays retracted until the arming switch or the emergency lighting is turned off. The brake is not wired to the siren motor circuit so the rotor will coast when power is switched off ....

Oh. Thanks.
It's whole purpose must be to prevent growling from ram air and it could also be used to stop the coasting siren upon 10-23.

Posted: **Mon Mar 26, 2012 9:39 pm**

Robert Gift wrote:Thanks for the interesting views, Henry.
Robert: Mars made a direct-drive large siren, the same size as a Q. It was their GD10 "Commander" siren; and yes, it rolled down very quickly. What a waste.By comparison, Sireno's ED10: their answer to the Q, was just slightly larger than a Q and would outroll it. Check out Henry's YouTube site, he has one of the big Sirenos that you can hear! My question: why would you want a siren that rolls down fast, you want all the sound you can get to get you thru traffic, if you have one in actual use.
So, do the sirens whose brakes engage when powered off spin down faster?
I wouldn't like that at all.
I want natural spinning down.
If the Q were direct-coupled to its motor shaft, would it slow noticeably faster?

Years ago, I spoke with someone at Federal about making Q sirens with half the ports so they would speak an octave lower.
They thought it an interesting idea.

I wonder what % sound output is reduced by all those stator protective ribs.
If I had a siren like that, I'd remove them and file the ribs smooth with the stator port edges.

On the M30 above, is there a sound quality difference if you remove the front cowling?
Would it not be.tter if exponentially flared intake?

The Siren Board

Forced air intake for a Q siren.