Contrary to what NPS Ranger stated, the 70 series, or Doubletones (not Dualtones) were coasters as well as the C and Q. They were equipped with clutches and had optional brakes. They did not coast as long as the C or Q simply due to the fact that their rotors did not create as much flywheel effect. I just love the comment that FDNY moved away from electro-mechanical sirens for "noise abatement" reasons. Kind of makes me think of the guy that put his car up on blocks to save on tires.
I have beem contacted by quite a number of FDNY companies who want to replace their peanut whistles with real sirens, and are chipping in to foot the bill for a rebuilt C, Q or B&M .
John Dorgan
QUOTE=NPS Ranger;188041]I'm not the expert here but I'll make a start at it. By the way if you go to the "catalog" sticky above and click on Federal and start at the LAST page working backwards you'll find a bunch of old catalog pages for Federal mechanical sirens.
They basically made 5 series, based on the diameter of the rotor. The Q was biggest, then the C. Both of these were coaster models, all the others were non-coaster. The 60-70 series was next, these were described as heavy duty and included the 28. The E-W-X-Y series was next and the smallest was the V series for volunteers.
You could also equip all but the V series with a "Pulsator" attachment which had sort of a flapper valve to vary the sound, in an era before electronic sirens and yelp came on the market. I've only seen these in the 60-70 series in person, it would be cool to find a Q Pulsator and they did list the variation in their catalog. By the way NYPD used the 28 underhood for decades, until the chromed Pulsators appeared on the roof starting in 1964 although unmarked continued to use the 28. The FDNY used the 28 mounted on the bumper or cab roof for apparatus and cars until NYC started the switch to electronic sirens in the late 60's for noise abatement reasons.