R1830 Reduction Gear Cover Removal Help

[Tumbawhere]

Long term viewer first time poster, apologies if this query is not in the correct section. I'm hoping that someone here with round engine expertise can assist or point me in the right direction.

I'm a volunteer at the Darwin Aviation Museum as part of the workshop team. We have an R1830 that we would like to section, with the aim of providing a full motion display for museum visitors to view the inner workings of a radial engine. Basically push the button and be amazed at the technology as the engine turns, big kids Lego.

The large slotted nut on the prop shaft, securing the dome covering the reduction gearing, is proving to be immovable. We have applied force, heat (lots of it), ATF/Acetone, more force, violence etc, but the thing remains immune to our efforts. No sign of movement at all.

Drawings that we can find on the web show the prop shaft with a short thread where the nut is located but no mention of the nut itself. There doesn't appear to be any pins, screws or other obvious devices securing the nut.

Does anyone here know if there is a trick to removing the nut? We presume it is a standard RH thread (righty tighty, lefty loosy), exploratory attempts at turning it in the opposite direction have not been successful.

Thanks in advance.

[Uplinker]

I don't know the answer but I would be very surprised if this nut was not locked in some way. It must have something to stop it coming undone in flight - and that something is obviously working !

There might be a grub screw hidden in a longuitudinal drilling between the nut and the shaft at one end of the nut, rather than a radial drilling on the side.

I am not an aircraft engineer but a photo might be helpful. Are you sure the nut is a discrete item and not part of the cover - in which case the locking device might be located elsewhere.

Secondly, I think this question would be better posted in Tech Log or Engineers & Technicians. :ok:

[Tumbawhere]

Thanks for your thoughts, much appreciated. All input helps as we are pretty stumped.
At this stage I can't put up a pic until my post count gets up to 8.

I agree that posting in the tech forum may reach a more specific audience, the rules around non-pros posting in the professional forums looked pretty clear though. Certainly happy for the mods to move it over though if they consider it appropriate.

I agree that there may be a pin/screw some place but we have been all over the thing. As the nut incorporates what appears to be a spiral oil slinger we'll run a sharp probe around the grooves to see if there's something hidden in there.

Thanks again, cheers.

[treadigraph]

NutLoose or tonytales might well know, I seem to recall that Tony worked on many of the classic propliners in the 1960s, so DC-3s may have benefited from his ministrations.

[Jhieminga]

Ideally, you would have access to a R-1830 overhaul manual or something similar, as that would provide the best information on how to take one apart (this place (https://app.aircorpslibrary.com/aircraft/pw-r-1830-twin-wasp-jr) could help. I haven't tried them myself though). That being said.... engines that have not been looked after for a while may not respond as you would like to regular disassemble practices. I too think you could try the Tech Log or E&T section. Other options are the WIX forum (http://www.warbirdinformationexchange.org/phpBB3/index.php) or the Historic section on UKAR (https://forums.airshows.co.uk/) as you may well find several spanner wielders in those places. The original Flypast forums were always a good place too, before Key butchered it.

Edit: some manuals here (https://ww2aircraft.net/forum/threads/pratt-whitney-r-1830-twin-wasp-maint-manual-r-1830-service-inst-manual.38038/) as well, but not the overhaul one.

[NutLoose]

You are sure it is not a right hand thread as opposed to a left hand one?

Cannot see it in here, but will help you.

https://ww2aircraft.net/forum/threads/pratt-whitney-r-1830-twin-wasp-maint-manual-r-1830-service-inst-manual.38038/

scroll down to link to download

https://ww2aircraft.net/forum/threads/p-w-r-1830-92.16570/


https://app.aircorpslibrary.com/aircraft/pw-r-1830-twin-wasp-jr

https://ww2aircraft.net/forum/threads/1946-navy-aircraft-engine-maintenance-manual.29428/

https://www.aircraft-reports.com/pratt-whitney-r-1830/

[Tumbawhere]

Thank you all for your replies, the links have been very helpful and we'll look at purchasing an overhaul manual. Just got to figure out which model the engine is as the data plate is missing, hopefully there may be something stamped on it somewhere.

Thanks to the links I've now identified the troublesome thing as the Thrust Bearing Nut, so it has a name rather than some of the other colourful descriptions it has been called recently...

As we have had no success in attempting to undo the nut in the traditional RH we may as well have a crack at applying some more robust force in the opposite direction, nothing to lose. The engine had been in the weather sitting on its back so rain would have collected around the prop shaft, no doubt there would be corrosion between the nut and shaft by now.

Again thank you to all who have responded, any other input or useful tidbits from those who may have had experience with these engines would be most welcome.

[Uplinker]

Since the engine is being prepared for display - never to run again - could you not simply cut the nut off ?

Using a small disc cutter, you could cut slots down two opposite flanks from the top to the bottom of the nut almost into the threads, then split the nut with wedges hammered in.

[BTC8183]

Some browsing revealed this 'nut removal' image.
https://cimg3.ibsrv.net/gimg/pprune.org-vbulletin/532x412/screenshot_20240316_131121_2_014708_01_2f4fc6f72462f3759f82c 6c52858985ac91c9248.jpeg

[Tumbawhere]

Oh thank you for the photo, that certainly clarifies the thread direction. A picture is indeed worth an abundance of words.

Cutting the nut off is definitely now part of the equation, though on removing the crankshaft we have discovered that all the rear timing gear and cams missing plus missing chunks of gear teeth.

Our idea of animating the engine will also require some further thought as our original plan of modifying the starter gear to run off an external electric motor has been scuppered by the absence of a lot of vital connections at the rear. All good fun.

Once again thank you all for your input.

[NutLoose]

Try?

https://www.liveabout.com/using-heat-to-remove-a-stuck-bolt-281713

[421dog]

What is the 1830 off of?
I have a plethora of radial mechanics in my circle who should be able to tell you exactly what is needed for nothing more than a smile…

[Tumbawhere]

Thanks for the link Nutloose, we did introduce the thing to Mr Oxy-acetylene, got it red hot and quenched it, then applied an electric jack hammer to no avail.
Not sure what the engine came off, no data plate. Best guess is either a B24 or C47.

If we can't get the nut off we may explore cutting into the dome insitu.

[sycamore]

Just spoken to a mate ,who has just been working on a c47 in France.He reckons there should be a small hole that has a small rubber `bung`,to prevent water ingress,but occasionally forgotten,so it corrodes,Best advice,use lots of dispersant/penetrant overnight,then try again ; if it wont budge,then a small disc cutter,down to the threads,rinse ,repeat...if you cut another one ,you can possibly spot weld the nut back `together`,if you need it again..(with a bit of filler)..

[Tumbawhere]

Given the state of the innards and missing bits of the engine it seems to have suffered a major failure and been donated to us after being ratted for salvageable parts. A fair chance the bung would have gone missing in the process, a few years out in tropical weather has certainly taken a toll.
Testament to the engineering that the reduction gears and front row (sans cylinders) turn fairly freely.
Thank you for the tip on cutting down through the nut, it's certainly worth a shot.