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HDN
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Model 5 Siren - Motor stuff

Mon Dec 31, 2018 12:36 am

I was playing around with my Model 5 today. My wife got me a new angle grinder for Christmas, so I fitted it with a thick rubber backing pad and used it to spin up my siren. It's the loudest it has ever been since I've owned it! While spinning it up, I noticed that it has a fast wind down compared to other privately-owned Model 5s I've seen on YouTube. I know that one reason is that it was about 35 degrees F outside when I spun it up, so the grease was thick. Even in the summer, however, it still has a faster wind down than other units.

The siren's motor has two grease ports: one where the rotor shaft meets the motor, and one at the tail end of the motor. They look like the type where you screw them in to force grease into the motor. Does anyone know how to refresh the grease in a motor like this? Will it involve a complete motor teardown? I don't think bearings are a problem as there is no lateral play with the motor shaft.

If a motor teardown is needed, I would be interested in re-motoring the siren to something that can run on single-phase power, probably 240 VAC. Has anyone done this with a Model 5?
~1950 Federal Enterprises Model 5 - 12-port
1995 AM General M35A3

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Re: Model 5 Siren - Motor stuff

Tue Jan 01, 2019 2:02 am

I have now uploaded a video of my spin-up to YouTube: https://youtu.be/MXrLMZRGBto

Compare its wind-down to this video: https://youtu.be/uiC1ob-5HYU

Hoping I can figure out why the motor is acting like this. Even when it's 70 degrees F outside it will wind down much quicker than the above 6-minute video.
~1950 Federal Enterprises Model 5 - 12-port
1995 AM General M35A3

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Re: Model 5 Siren - Motor stuff

Tue Jan 01, 2019 6:23 pm

I don't own a Mod. 5 but I do have knowledge of the electric motor side....
The grease that was put into those two ports eventually does thin and gets slung around. Yes, to remove all of the grease ,you will have to disassemble the electric motor....the motor frame and end shield or casing and the end piece that is removable.
Use a cleaner designed for electric motors....other grease and oil removers could damage the windings or other electrical components.
The fast wind down could be resistance related....something is keeping the shaft from freely spinning...bushings or bearings needing replaced, an issue with the brush assembly or a loose winding coming in contact with the rotor could be suspect.
If it were me I would first properly lubricate the motor....if it still has the fast wind down then tear it down and find out why...if it seems to have freed it up and there is a longer wind down, problem solved.
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Re: Model 5 Siren - Motor stuff

Tue Jan 01, 2019 6:32 pm

This is a pretty old 5, but not old enough to have the very heavy cast iron rotor! Those go for minutes, not seconds.
As mentioned above something is definitely wrong there. The reason for all the resistance when turning in general is also mentioned above and requires a rebuild. One thing to note here, as yours is older the motor is more exposed and should help you in the long run, however I have no clue as to whether it's a sleeve or a standard ball bearing. I'm assuming it's the latter. When rebuilding it might also be a good idea to clean up the field etc. to make it happier than it was.

Adding thin oil might help it turn better but it definitely sounds like it's wanting some TLC. Of course, when in doubt, call the motor people.
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Re: Model 5 Siren - Motor stuff

Wed Jan 02, 2019 12:54 am

Thank you both for your input. I need to get more pictures of my siren on my computer and post them here so that everyone can get a better look at this Model 5. I was told the siren was installed at its original location in the late 40s or early 50s. I have no idea how often it was run, other than that it was last run in the early 90s.

The chopper looks like it was pressed on or shrunk-fit onto the motor shaft. That's my biggest concern right there, getting it off, which I imagine would make motor teardown easier.

Also, I'm wondering about re-motoring the unit. I will probably have no access to 3-phase power in the future, nor will I be willing to screw around with a phase converter. Has anyone re-motored an old siren? I would try to replace it with a modern single-phase 5 HP motor that would be relatively maintenance-free and be far more energy-efficient. I imagine that the chopper would probably have to be bolted onto the motor shaft if I can't find a near-perfect match.
~1950 Federal Enterprises Model 5 - 12-port
1995 AM General M35A3

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Re: Model 5 Siren - Motor stuff

Wed Jan 02, 2019 4:16 pm

You'd best stay with its current motor and phase for now, after all, that's what the siren core was designed around! Federal played around with their motor ratings but it's safe to assume it's 5 horsepower. It could also be 7 given it's 3 phase but take that with a grain of salt. You're lucky in this case that the stator bolts on to the motor bearing cover and is not part of the motor itself. Federal did make 5Bs that had the exact same arangement but with a repulsion-induction motor instead for single phase. Not sure if it was any more efficient than the 5A's 3 phase motor. Because of how propreitry the siren is you'll have a hard time finding a replacement without getting another siren in itself to fulfill what you want, however you might be able to find a capacitor start-run motor from Baldor or someone that will fit the chopper and work, but you'll need to do some engineering to get it to hold up the stator as well.

The chopper, as I remember, was pressed on with a key for rotation force transfer etc. but since it's so old and corroded a puller and every kind of penetrant will probably be needed for it to budge.
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Re: Model 5 Siren - Motor stuff

Fri Jan 04, 2019 1:26 am

HDN wrote:
Tue Jan 01, 2019 2:02 am
I have now uploaded a video of my spin-up to YouTube: https://youtu.be/MXrLMZRGBto

Compare its wind-down to this video: https://youtu.be/uiC1ob-5HYU

Hoping I can figure out why the motor is acting like this. Even when it's 70 degrees F outside it will wind down much quicker than the above 6-minute video.
I don't generally see anything wrong with your unit, though that doesn't mean it's in perfect condition as it's most definitely time for new bearings. Your siren is an actual Model 5, the 15" rotor and 5HP motor model. The video you compared it to was actually a Model 7, the 18" rotor and 7.5HP model. Many people own Model 7s that Federal falsely stamped as Model 5s. Why they did this beats me, but it is extremely crucial to remember that the Model 5 and Model 7 are nowhere close to the same thing.
My knowledge excels on the Federal Thunderbolt siren and SiraTone EOWS sirens. ¯\_(ツ)_/¯

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Re: Model 5 Siren - Motor stuff

Fri Jan 04, 2019 3:07 am

The Federal Enterprises dataplate on the shroud shows that it's a Model 5 3-phase unit with an input of 208 volts and 40 amps. That's 14.4 kW input anyway.

(Energy Engineer Mode): If the motor output is in fact 5 horsepower, that means the motor's efficiency is about 25%! I'm not sure what efficiency was typical of electric motors at the time this thing was built, but that seems awful low to me.

The chopper itself appears to be made of aluminum. I heard some of these choppers have magnesium in them, but I'm not sure how I can tell, especially if I want to apply heat to the hub to help with getting it off the motor shaft.

I'm working with my local historic truck group to try and find someone who knows more about these old 3-phase motors. If I'm going to have the siren apart, I figure that this would be the time I would decide to keep its original 3-phase motor, or somehow adapt a single-phase motor to it so that I can actually run it on my household 220. If I do decide to go with a single-phase retrofit, I would definitely keep the old motor around. I don't like throwing out original parts to anything unless they're ordinary nuts and bolts.
~1950 Federal Enterprises Model 5 - 12-port
1995 AM General M35A3

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Re: Model 5 Siren - Motor stuff

Fri Jan 04, 2019 4:49 pm

The chopper should be plain aluminium. If there is any Mg content inside it shouldn't go burn as it's proportion to the aluminium will be very low.

The efficiency doesn't surprise me, given it's +-50 years old. I'm sure many motor shops will be able to service the one on your siren.
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