stuck linear actuator

[dave.zap]

Hi, I'm new to the forum.

Pictures below are of a linear actuator from a large satellite dish - hence posting this in this group I'm not sure where it should go.

It is driven by an electric motor that I've removed. The gear housing is the large box on the right and the threaded shaft is canvas cover on the business end but not the back end. It's here I think perhaps dirt has entered? But what ever the case it will not in and out when I manually turn the drive. It has been sitting in place (outside) without being serviced or used for about 10 years.

So I've pulled it apart and found that the main 'screw' thingy (I'm going to struggle with the correct names for things here) is frozen to the main shaft. This is shown in the second picture.

I've sprayed a lot of CRC into both ends but I can't make it budge.. No idea if the thread on the inside is damage or if it's just crime or what's going on. But I would really like to fix this.. what are my chances please help. All advice is welcome.

I'm in LOCKDOWN in New Zealand !!!

 

[Vetech63]

I would figure out a way to drop it in diesel or atf and let it soak in it for a week.

 

[DMiller]

That appears a Acme thread screw, it does not have a recirculating ball system in the geared head by chance?

 

[John C.]

What turn against that worm wheel? I'm guessing that a long soak and then working that center piece back and forth on the thread with a lot of force is what is needed to break it loose. You might have to put the monster back in the case and use what ever turned it to have enough force. It might also need to be heated up a bit. Good Luck!

 

[joe--h]

My go would be tap the bearings off, work around them with a punch tappy tap and they'll come off.
Then remove the gear and apply heat .
Get a piece of 1/4" strap as wide as the flange the gear bolts too and cut a notch in it to fit around next to the flange. Drill it for a couple bolts and attach to flange. Bang it with a hammer both ways and eventually if it just crud it will come loose.
As it looks like a bronze gear I'd think the teeth would strip before it buggered the threads.
Joe thoughts for the day.

 

[dave.zap]

Thanks All,

Yes I can tap the bearings off. Incidentally the left bearing spins freely while the right one does not and feels a bit rough, this bearing has been taking the weight of the dish for 10 years to this is not surprising. The bronze gear also slides off once you undo all those bolts.

So I'll disassemble further, soak for a while, then heat and wiggle. I'm also worried about damaging the other gears if I try to apply force that way.

@DMiller : I don't think it has a recirculating ball system ( I had to google that ) but I've not pulled the rest of the gearing apart as it is moving freely. But it is driven by something like the picture below.

 

[DMiller]

Could very well have been that rough bearing, under load they only get tighter and harder to rotate.

 

[dave.zap]

I would expect to be able to budge the worm wheel on the shaft at least.

 

[56wrench]

just don't wreck anything brass or bronze. they will be hard to find and expensive

 

[cuttin edge]

Must be the dish that tracks the international space station

 

[dave.zap]

Yes how rude of me, here are some pics.. The dish is 4.6m diameter - If it were tracking anything I think it would not be stuck now it was pointing at geostationary satellite so never moved except for calibration alignment but I don't have a record of when that was done last.

Last picture is of the stuck actuator with motor attached drives vertical elevation.

Thanks again for the ideas, I'll put some effort in to it this weekend.