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  1. #1
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    Default Does Your Q Siren Not Coast Down Like it Used to?

    After a few times of having this phenomenon, and alot of tinkering, I have found the most common cause for Q siren issues. Being responsible for the maintenance on 8 trucks that have them I've had a chance to take them apart a few times and I thought I'd share my expierences with everyone so that you can easily fix a very simple problem.

    If you have a Q siren and it winds down very quickly after you let the pedal go, the following is the most likely cause and repair. If you arent sure, try comparing the coast down times of two different sirens. A well trained ear can tell the difference. Essentially, you should be able to lightly tap the button and get about 30 seconds to a minute of coasting befire the siren stops completely.

    The following contains terms that you might not find 100% mechanically correct, but hopefully you get the ideas!!

    First, understand the basic operating principle of the siren. A very high powered motor that spins a rotor and creates the siren noise. The rotor is mounted on the motor shaft and has a closed bearing assembly that it sits on. Attached to the outer face of the rotor is what I would call a cork type of disc. At the very end of the shaft is a brass wheel (clutch) mounted on a worm gear. When you press the siren button, the spinning (centrifugal force) of the motor draws the clutch wheel into the disc and "bites" down, turning the rotor and producing the increase in siren pitch. When you release the siren button, the clutch wheel is supposed to release and "float" back on the worm gear to allow the rotor to continue free spinning on the downward pitch until you either depress the button again or it stops. The bearing that the rotor is mounted on allows a smooth and long downward spin.

    What happens when you abuse the siren, is that the clutch mechanism freezes to the rotor, and instead of the siren winding down on the smooth rolling bearing, it winds down with the electric motor. Even if you have a nice clean motor, it doesnt take long for it to wind down and stop spinning. Abuse is when you pin the siren button down and allow it to scream at peak rotation for more than a few seconds. Some people think this is an effective siren use. In reality it only damages the unit.

    Here is the simple fix.

    1. Remove the 4 screws on the front of the siren that hold the face plate on. This is the part with the "F" on it. Take the face plate off.

    2. Remove the 3 screws that hold the back housing on. Take the cover off.

    3. Remove the 3 screws that hold the small cover on the siren shaft, these are inside the rotor on the front of the unit.

    4. You shold now see the brass clutch mechanism mounted on the motor shaft. Spin the rotor and see if the clutch mechanism is stuck to the rotor mechanism. When you spin the rotor, it should spin free and easily and coast nice and smoothly. The brass clutch wheel should sit free of the rotor and not spin.

    5. If the brass wheel is stuck to the pad on the rotor, try a few taps with a hammer to loosen it. If this is unsuccessful, utilize large channel lock pliers or a pipe wrench to turn the brass wheel. On the back of the motor is a piece you can attach a vise grip or other wrench to keep the shaft from spinning while you perform this trick.

    6. Once free, test the siren by tapping the pedal a few times to see if the clutch wheel sticks to the rotor again. If it still gets stuck, use a VERY SMALL amount of multipurpose oil or WD40 to lubricate between the front face of the clutch wheel and the end of the motor shaft. DO NOT get any oil or grease between the clutch wheel and rotor. Doing this will cause the clutch pad to get slippery and the clutch mechanism will not grab properly. This will cause the siren to not wind up. Each time you tap the siren, it should wind up and when you release the pedal it should let the brass wheel spin free so the rotor can coast down.

    7. Reassemble and promptly beat the worst offenders of Q siren abuse.

    Hopefully this helps. If needed, I can take pictures of this process for anyone whl may need additional insight. Its a 10-15 minute fix in most cases. I encourage you to examine the components closely before banging and messing with stuff. As always, the manufacturer probably has some liability statment and maintenance booklet you should read first as well.

    To prevent this problem, don't pin the siren at its peak for more than a few seconds at a time. It's designed to be wound up and coast down at varying levels. Continuous operation at peak rotation causes the clutch to "weld" to the rotor and decreases the performance of the unit.
    Last edited by MG3610; 12-30-2005 at 06:03 PM.


  2. #2
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    Default

    I need more information from "those who know" about the Q...

    The brakes on some seem really good while the brakes on others seem really lousy.

    Seems like the bumper mounts are worse than the grille mounts. Why? They seem the same to me.

    I have checked the pad material and really don't know what else to look at... what else could make a siren brake just not work right?

    On 2 of our 4 trucks, the brake will take the siren from peak to stopped in like 15 seconds or less.

    On the other 2 (bumper mounted), it takes forever. Minutes. Perhaps the bumper mounting is coincidence, just thought I'd mention it.

    Ideas?

    Jon

  3. #3
    MembersZone Subscriber krg1401's Avatar
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    Default

    Chiefeng7 -
    Is there much of a difference in age between the two groups? On the B/C model and D model Federal Signal improved the entire brake assembly. Try going to the website fedsig.com and check there. Hope they can help.
    IACOJ

  4. #4
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    Default

    Yeah there is. The old ones stop fine! The (second) newest one in the batch, a Y2K, is the one that is lousy to stop.

    Jon

  5. #5
    Forum Member IronsMan53's Avatar
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    Hey MG3610. The other day I noticed our Q winding down fairly quickly and I remembered your thread on here with a smile. I worked on a Q2B "C" model a few years ago to correct the problem that you have illustrated here. So I shouldn't have any problem fixing this siren right??? wrong...

    It seems that we have a "D" model on our current engine. This siren has a one way bearing instead of a worm gear clutch. The one way bearing was frozen solid. I was able to break it loose and exercise the bearing a little bit but every time we would spin the motor up to test the siren the bearing would lock back up and not coast at all. I believe our only recourse is to put a new $50 bearing assy in.

    BTW, I don't like these new "D" model Q's. Even when the one way bearing is operating properly they still spin down quicker than the older clutch operated models.
    I can't believe they actually pay me to do this!!!

    One friend noted yesterday that a fire officer only carries a flashlight, sometimes prompting grumbling from firefighters who have to lug tools and hoses.
    "The old saying is you never know how heavy that flashlight can become," the friend said.
    -from a tragic story posted on firefighterclosecalls.com

  6. #6
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    Default

    I wasn't aware of the various models out there, but its good to know someone got some use out of the advice (or tried!)....anybody else try the repairs yet?

  7. #7
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    Can someone tell me if the Q2B has to be mounted horizontally? Can it be mounted downward at a 45 degree angle?? Thank you

  8. #8
    Forum Member Dave1983's Avatar
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    Question

    Hmmm, we have Q's on all our rigs. On the newest rigs (an '01 and two '02s) the Q's not only wind down faster, but they wind up faster then the others ('93 and older). The "pitch" doesnt sound the same either.

    I just assumed this was a change in the design of the sirens. I say this as there was a similar difference in the Q on our '54 LaFrance tiller that we used to have. It reacted/sounded different then any of the ones we have now (old or new).

    Oh, and I noticed this difference as soon as the new rigs were in service. I find it hard to belive they needed a repair right out of the box.
    Last edited by Dave1983; 01-10-2006 at 11:27 AM.
    Fire Marshal/Safety Officer

    IAAI-NFPA-IAFC/VCOS-Retired IAFF

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  9. #9
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    Dave,

    Yes, I also noticed this new Q siren phenomenon. I should have been more specific with the vintage of the units. I really can't though since I'm not sure when these new ones came out. They sound alot more what I'll call "electronicy" than the old ones.

    My post applies only to older models (pre 2001-ish)

  10. #10
    Forum Member IronsMan53's Avatar
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    Our "D" model Q is on a 2000 model engine. I noticed these sirens winding down quicker than the older models immediately, but it has gotten worse lately. The one-way bearing was definitely frozen. A new one is on order.

    I think that the newer ones slow down quicker because one-way bearings aren't as efficient as standard bearings. Why did they change from the worm gear clutch to one-way bearings? It can't be reliability. We've never really had any problems with our older Q's. It's just the opposite... In fact, I found out after talking to maintenance that there are several of our new sirens with frozen one-way bearings in them. I believe they changed the design as a cost saving measure because they thought the could get the same action out of one bearing instead of having brass clutch assembly (which is obviously more expensive).

    I believe that the "D" model Q is a step backward and is probably the worst Q that Federal Signal ever released.
    I can't believe they actually pay me to do this!!!

    One friend noted yesterday that a fire officer only carries a flashlight, sometimes prompting grumbling from firefighters who have to lug tools and hoses.
    "The old saying is you never know how heavy that flashlight can become," the friend said.
    -from a tragic story posted on firefighterclosecalls.com

  11. #11
    capfiremedic
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    Default

    There's a guy named John Dorman www.sirenman.com who rebuilds old sirens and lights for a living. As far as I know, he's worked with most if not all the old electromechanical sirens that have been built. He put an e-mail addy in his site and could prolly offer some advice as to those brakes.

  12. #12

    Join Date
    Jun 2007
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    1

    Default Q Siren Repair

    Has anyone experienced a Q siren that winds Up slowly? I think my clutch is slipping. I have an OLD OLD Q siren. This thing doesnt have the brass clutch. It seems to have two clutch pads that lock by centrifugal force. My q siren also doesn't have the pasrt on the back to secure the shaft. I have a cover and some ball bearings. How would I remove the clutch assembly safely?

  13. #13
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    Default

    Yeah, our Q takes forever to build up to full db. Ours is in a '96 Ferrara/Spartan program truck. Our mechanic says there's nothing wrong with it, but I'm thinkin I'll take a look see after this thread.
    FTM-PTB-EGH-RTB

    Stay low, keep pushing in, and stay safe.

  14. #14
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    Im experiencing a problem with grinding noise with the Q. When you start to wind it out and it winds down you hear a grinding. ANy clue to what this might be and how to fix it?

  15. #15
    Forum Member GonzaloBravo's Avatar
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    Default

    Quote Originally Posted by MG3610 View Post
    After a few times of having this phenomenon, and alot of tinkering, I have found the most common cause for Q siren issues. Being responsible for the maintenance on 8 trucks that have them I've had a chance to take them apart a few times and I thought I'd share my expierences with everyone so that you can easily fix a very simple problem.

    If you have a Q siren and it winds down very quickly after you let the pedal go, the following is the most likely cause and repair. If you arent sure, try comparing the coast down times of two different sirens. A well trained ear can tell the difference. Essentially, you should be able to lightly tap the button and get about 30 seconds to a minute of coasting befire the siren stops completely.

    The following contains terms that you might not find 100% mechanically correct, but hopefully you get the ideas!!

    First, understand the basic operating principle of the siren. A very high powered motor that spins a rotor and creates the siren noise. The rotor is mounted on the motor shaft and has a closed bearing assembly that it sits on. Attached to the outer face of the rotor is what I would call a cork type of disc. At the very end of the shaft is a brass wheel (clutch) mounted on a worm gear. When you press the siren button, the spinning (centrifugal force) of the motor draws the clutch wheel into the disc and "bites" down, turning the rotor and producing the increase in siren pitch. When you release the siren button, the clutch wheel is supposed to release and "float" back on the worm gear to allow the rotor to continue free spinning on the downward pitch until you either depress the button again or it stops. The bearing that the rotor is mounted on allows a smooth and long downward spin.

    What happens when you abuse the siren, is that the clutch mechanism freezes to the rotor, and instead of the siren winding down on the smooth rolling bearing, it winds down with the electric motor. Even if you have a nice clean motor, it doesnt take long for it to wind down and stop spinning. Abuse is when you pin the siren button down and allow it to scream at peak rotation for more than a few seconds. Some people think this is an effective siren use. In reality it only damages the unit.

    Here is the simple fix.

    1. Remove the 4 screws on the front of the siren that hold the face plate on. This is the part with the "F" on it. Take the face plate off.

    2. Remove the 3 screws that hold the back housing on. Take the cover off.

    3. Remove the 3 screws that hold the small cover on the siren shaft, these are inside the rotor on the front of the unit.

    4. You shold now see the brass clutch mechanism mounted on the motor shaft. Spin the rotor and see if the clutch mechanism is stuck to the rotor mechanism. When you spin the rotor, it should spin free and easily and coast nice and smoothly. The brass clutch wheel should sit free of the rotor and not spin.

    5. If the brass wheel is stuck to the pad on the rotor, try a few taps with a hammer to loosen it. If this is unsuccessful, utilize large channel lock pliers or a pipe wrench to turn the brass wheel. On the back of the motor is a piece you can attach a vise grip or other wrench to keep the shaft from spinning while you perform this trick.

    6. Once free, test the siren by tapping the pedal a few times to see if the clutch wheel sticks to the rotor again. If it still gets stuck, use a VERY SMALL amount of multipurpose oil or WD40 to lubricate between the front face of the clutch wheel and the end of the motor shaft. DO NOT get any oil or grease between the clutch wheel and rotor. Doing this will cause the clutch pad to get slippery and the clutch mechanism will not grab properly. This will cause the siren to not wind up. Each time you tap the siren, it should wind up and when you release the pedal it should let the brass wheel spin free so the rotor can coast down.

    7. Reassemble and promptly beat the worst offenders of Q siren abuse.

    Hopefully this helps. If needed, I can take pictures of this process for anyone whl may need additional insight. Its a 10-15 minute fix in most cases. I encourage you to examine the components closely before banging and messing with stuff. As always, the manufacturer probably has some liability statment and maintenance booklet you should read first as well.

    To prevent this problem, don't pin the siren at its peak for more than a few seconds at a time. It's designed to be wound up and coast down at varying levels. Continuous operation at peak rotation causes the clutch to "weld" to the rotor and decreases the performance of the unit.
    That's great hint.

    Would you please post pictures of it? My Q2B seems to have the "ball & ramp" clutch type, and can not find how to disenble it.

    thanks in advance

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