Shaft and Coupling nightmare

[Sandrine]

Good afternoon all.

I was wondering if any of you had a magic receipe: I have tried to remove the shaft this weekend, the prop went OK, but inside the boat, the coupling seems to have a firm grip on the shaft.

I can see there is a key, and I removed 4 grab screws (2 on top on each other)
I cannot see anything else (pin???), and its not moving

It is bathing in WD40, poured some boiling water on it
I have tried a puller, but did not move
I have tried bolting it back to the gearbox with a nut in between, but that did not pull the shaft out from the coupling either

I have been suggested to use a blow torch but I am not great at that because of the proximity of the diesel tank (and probably the fact that there is old oil a bit everywhere)


any suggestions ?
Cheers

BTW, boat is HUSTLER 35 (1971)
Engine is Perkins Perama

 

[ShipsWoofy]

Can you provide a better description of the coupling?

A photograph perhaps.

 

[macd]

Just a thought: two pairs of grub screws, one on top of the other. Are you sure it's not a PSS shaft seal you're trying to pull apart?

 

[Sandrine]

I am clearly not great at drawing, but maybe this may give you a better idea:

http://uk.geocities.com/pagan_maid/img/coupling.gif

Cheers

 

[macd]

Drawing looks clear enough to me. I take it there isn't room to unbolt the flange from the gearbox and withdraw the shaft forwards?

 

[BobOwen]

I'd try the puller again. Once its really tightened, whack the coupling with a hammer, turn puller half a turn, whack and repeat.

Heat can really help too - can you cut up an old can or something to use as a heat shield? Used in conjunction with the above 'surgical' technique, it should come off.

 

[Sandrine]

I am afraid I have no space indeed to withdraw the shaft fwd

Sound like I'll play with hammer and puller, just read elsewhere that sometimes, the only way it to cut the shaft ...

scary, I'll try the rest first
Cheers

 

[supermalc]

When I took my coupling off, one of the grub screws was over the key. I'm sure you've looked but is there a thirds grub screw on your coupling.....under some paint for instance.

Years ago I worked as an agricultural engineer, and remember a similar experience where a similar coupling had been loose, resulting in a step in the keyway. Strugging in a field for hours on a cold day is one even my bad memory retains /forums/images/graemlins/smile.gif Probably one of the reasons I left the job a few months later.

 

[sequena1]

Hi. Had a similar problem dismantling my shaft and coupling a couple of years ago as part of a major refit.The two hadn't been parted for a decade or so. Spent hours as you have working up in profanity levels and brutality. The only thing that worked eventually was to drill two holes in a half inch steel bar corresponding to two holes in the half coupling and to bolt them together with a nut in between--- as you did. tighten the bolts hard then use a lump hammer to thwack the steel bar END-ON over the nut. Retighten and wallop again. It took two hours and the only thing holding them together was
dirt and corrosion. Good Luck

 

[capsco]

Are you sure there is not a big nut inside the coupling holding the flange onto a taper

 

[JAYEL]

Bet there is a nut on the end of the shaft burried down in the boss of the coupling, there was on my trapper. I had to lever up the engine on to blocks and pull the shaft out forward.

 

[Birdseye]

one old engineers trick when you get something corroded inside a fitting (eg the pin in a shackle) is to take 2 hammers and hit opposite sides of the fitting simultaneously. Using this technique I have never yet failed to undo the shackle pin on my moorings.

Failing that I would clean out the bilge and insulate the diesel tank and then use a hot air gun on the coupling.

Or split the coupling, slide it forward and then hammer out the shaft from the gearbox end.

But try loosening up the coupling wwith the hammers first - it works wonders

 

[billcowan]

When you are certain that there is NO reason it wont come off other than just stuck.

heat it up with a propane torch (mask off any nearby flammable things like rubber pipes and GRP hull etc. with bent bits of metal sheet.

when realy hot - whack it with a BIG hammer (can use lump of oak inbetween to avoid damage.)

a big Arc welder used to run a big weld down the side of the boss is another way to make it lose the will to grip. (flange has to be steel not cast iron though)

 

[Spyro]

Sandrine
I have sent you a PM

 

[Sandrine]

Thanks all for the answers and advices.
The nightmare is over. After 2 week-ends of banging and bashing the couplig, I eventually decided to cut the shaft and replace both coupling and shaft.
I am now 350 pounds poorer, but 've got brand new coupling, easily taken away from the shaft this time...

P.S.: Spyro, never received your PM...