The Siren Board

Hello everyone

I am working on a Thunderbolt project, and I can't get the stator to separate from the chopper housing assembly. Won't budge at all. Also, the rotation will not go by hand, will only rotate when pulling on the belts. Not sure if that matters or not for this particular issue. Any of you professional experts have any suggestions? They stopped making these when I was three years old, this unit is my parent's age haha.

Thanks for stopping by :D

I believe the rotator gearbox is not backdriveable, IE you cannot rotate the siren by pulling on the siren head itself, but you can rotate it by moving the belts.

Huh. Ok. Haha
The one sitting next to it can be moved by hand, so I assumed there was something wrong with this one. Never knew there was any difference from one to the next. Even the manual says it should be able to be spun by hand. Guess I will just accept what it is.

Do you have any idea what I should try doing to pry apart the stator & chopper housing? Doesn't want to budge at all. Even with a pry bar

Thunderbolts do have a clutch between the gear drive and the chopper tube to allow it to spin in the event of high winds or some sort of mechanical problem, so yours must either be seized or extremely tight. If you get a look inside it sits right above the large spur gear.

As for the chopper cap, penetrating oil is your best friend. There are a few bolts (4 I believe?) and some metal dowels that hold it to the chopper tube, so if you let the hardware soak for an hour or so it should loosen up nicely. Just don’t code things if you can avoid it. A broken/stripped bolt is another nightmare you want to avoid if you can. I hope this helps!

I have poked at the clutch, loosened it as much as it would go without removing it completely, and she still won't turn by hand. It's not very rusty at all. I will remove it completely and see what happens. If that works I will order a new one

I have all the bolts removed from the chopper cap, they are nice stainless fasteners. Those aren't the problem this time, she still won't separate from the chopper housing for some reason. Won't budge in the least

Chicagosiren-hunters you earned 5 bonus points for the clutch issue. Got that dealt with
Still stuck on the chopper cap not wanting to come off the housing. It appears the chopper itself is seized, won't turn when I poke at it with a screwdriver. Not sure if that has anything to do with the cap not coming off

fr4ie2nd0ly wrote: ↑

Fri Jul 30, 2021 3:15 am

Still stuck on the chopper cap not wanting to come off the housing. It appears the chopper itself is seized, won't turn when I poke at it with a screwdriver. Not sure if that has anything to do with the cap not coming off

What are you calling the "chopper housing", do you mean the steel tube, or the aluminum chopper casting that holds the brushes and field coils inside? The problem here is that there are (usually) three different metals sandwiched here: steel housing, aluminum motor frame, bronze stator cap. Aluminum in particular oxidizes to the dreaded "white rust", which can grow around bolts and edges of parts and bind things together with incredible resilience. But... the three metals also have very different thermal expansion rates, which means if you heat the thing with a torch, the parts will expand to different diameters and very possibly pop apart for you. Obviously you need all the fasteners out before you apply any heat. Also, no oil or solvent is likely to help much if the cause is oxidation, but if you've already tried this, heating is going to make LOTS of smoke, so gotta work outdoors if you aren't already.

Also, the "dowels" Chicagosiren-hunters mentioned are actually taper pins used to align the stator with the motor frame, and as such can only be tapped out from underneath. If you tap them from the top, you wedge them in even tighter and risk cracking the aluminum casting if you really overdo it.