Removing shaft from R&D coupling

laika

laika

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Further to my earlier thread on my dripping shaft seal (grease insertion did radically reduce the dripping so thanks all, but it’s 11 years old), boat is now on the hard. pvb identified my Yanmar coupling as an “R&D coupling”. I have never undone this. Is it simply a case of undoing the 4 bolts which are perpendicular to the shaft, possibly prising the “jaws” apart with a screwdriver, sliding out the shaft then reversing the operation, tightening the bolts as tight as possible after the new seal is fitted? Or does this need removal of the coupling from the gearbox then using the shaft puller I don’t have to take it off the shaft?

None of my books seem to reference this coupling and I have form for undoing a load of bolts only to find I’ve misunderstood how a thing is put together.


IMG-0249.jpg
 
The one on my previous boat worked as you surmise, no keyway or key, just clamping friction.
Pulling on the prop blades and waggling after loosening the bolts should be fine.

If recalcitrant, put a spacer on the shaft end and wind in longer flange bolts to expel the shaft.
 
I put one of those on with the new engine last winter. A friend pleaded with me to get some threaded holes drilled so that I would be able to insert bolts and open up the coupling should I need to withdraw the shaft at some point. I didn't but think I should have.

Another thing I should have done was measure the shaft diameter before I bought the coupling. I put it all together and then discoverd the shaft was 25mm rather than 1". Couldn't send it back because there were obvious marks from tightening. So if anyone is looking for a 1" coupling in near new condition ...
 
laika said:
Further to my earlier thread on my dripping shaft seal (grease insertion did radically reduce the dripping so thanks all, but it’s 11 years old), boat is now on the hard. pvb identified my Yanmar coupling as an “R&D coupling”. I have never undone this. Is it simply a case of undoing the 4 bolts which are perpendicular to the shaft, possibly prising the “jaws” apart with a screwdriver, sliding out the shaft then reversing the operation, tightening the bolts as tight as possible after the new seal is fitted? Or does this need removal of the coupling from the gearbox then using the shaft puller I don’t have to take it off the shaft?

It should come apart just as you surmise. Your access looks better than on my Sadler. After slackening off the split coupling bolts , I resorted to separating the flanges at the back of the gearbox, inserting a socket between the two faces and then re-tightening using longer bolts to push the shaft out. In my case it had not been disturbed for a long time and was securely stuck..
David Morgan


View attachment 119335
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laika said:
Further to my earlier thread on my dripping shaft seal (grease insertion did radically reduce the dripping so thanks all, but it’s 11 years old), boat is now on the hard. pvb identified my Yanmar coupling as an “R&D coupling”. I have never undone this. Is it simply a case of undoing the 4 bolts which are perpendicular to the shaft, possibly prising the “jaws” apart with a screwdriver, sliding out the shaft then reversing the operation, tightening the bolts as tight as possible after the new seal is fitted....
Click to expand...

One thing - tighten bolts "correctly", not "as tight as possible".
 
The smaller R&D shaft couplings do not have a keyway, so just releasing the clamping bolts is theoretically all that's needed. Of course, it's likely that removing the shaft will be a bit of a struggle!

I'd be tempted to talk to R&D and ask what the correct tightening torque is for the bolts.

R and D MARINE : Flexible Shaft Couplings
 
I have one of those and remove the shaft every year to clean the crud off from under the cutlass bearing. There is no key, it just clamps. I find it best to remove all the bolts (not just loosen them). I then tap a flat blade screwdriver into the gap on one side parallel to the shaft allowing the tapered blade of the screwdriver to open the gap. If I do it right the shaft just slides out without effort.
 
Poey50 said:
There is no key, it just clamps. I find it best to remove all the bolts (not just loosen them). I then tap a flat blade screwdriver into the gap on one side parallel to the shaft allowing the tapered blade of the screwdriver to open the gap.
Click to expand...

Bolts are out and I tried this before reading this post. With advice from previous threads about not hammering I was doing it a bit gingerly and with no effect. I’ve tried pulling from the prop end but still no joy. Should I just try hammering harder? I’m nervous of damaging bearings
 
Undo the coupling from the gearbox, push back the shaft, insert a spacer such as a socket between the end of the shaft and the nut that holds the half coupling onto the gearbox. Put the coupling bolts back in and tighten up. This will push the shaft back out of the coupling. You may well find you only need to push it back a bit before it is loose enough to pull out from the prop end.
 
Tranona said:
Undo the coupling from the gearbox
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Is this the panel’s consensus, that I might not be able to remove the shaft without removing the coupling from the gearbox? Previous posts were suggesting this might not be necessary but I guess it doesn’t look too hard. No room for a socket there so it’ll be spanner’s only even if I could find my torque wrench
 
laika said:
Bolts are out and I tried this before reading this post. With advice from previous threads about not hammering I was doing it a bit gingerly and with no effect. I’ve tried pulling from the prop end but still no joy. Should I just try hammering harder? I’m nervous of damaging bearings
Click to expand...

You don't want to be whacking it, but if you have a suitably tapered screwdriver for a wedge a few sharp taps does it for mine. The finer the taper the more the force will go into opening the gap rather than stressing the gearbox. Or at least that's how it works in my head. Yours may be more stuck than mine since mine comes off annually.
 
A friendly engineer showed me what I was doing wrong. Essentially Poey50 had the right idea, I just wasn't using a big enough 'ammer and being too ginger. It was, he said, rather more than averagely stuck in and extraction did involve pulling and twisting from outside with the coupling being held.

As someone who has had pretty much consistently negative experiences with marine engineers since becoming a boat owner I'd like to mention that I've been thoroughly impressed by West Marine in Brighton who I've recently become a customer of: they've been super helpful with advice (into the zone where I think I'm pushing my luck...) and it's something of a relief to find some people I'd be happy to engage to do things I wouldn't fancy doing myself.
 
What Tranona said

To get ours off took three different lengths of spacer (longer and longer sockets!) and i had to switch to some longer bolts too but eventually it came free

Despite being apprentice trained, i only resort to the Birmingham Screwdriver when all else has failed :)
 
Clamp type couplings are widely used although perhaps Yanmar are the most common. The Vetus Bulflex on my old boat also used this method. They can be a pig to remove. Some come out easily after opening the gap others need more persuasion. The method I described is idiot proof but does require a bit more work. If you have plenty of room to move the shaft aft you can also use a puller, but the principle is the same.
 
Using a socket to try to force the shaft out will work, but it's a lot of messing about, and I'd only try it as a last resort.

The old Volvo clamped coupling was great - you could slide a bit of steel into the slot, reverse the bolts in their holes, and just jack the coupling open.

shaftcoupling.jpg

Photo from Vyv Cox's excellent website.
 
Last 25mm I pulled was keyed. Used the screwdriver wedge and a light tap (or two) was enough to move it. No corrosion about, a plus.. Reason to pull it was the flex coupling supplied by Beta was a different PCD to the original Yanmar, so had to re-drill the shaft flange.
I thought the R&D refered to the flex coupling?
BTW, The link about not hitting it is about damaging the gearbox. In this case the engine was not connected.
 
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pvb said:
Using a socket to try to force the shaft out will work, but it's a lot of messing about, and I'd only try it as a last resort.

The old Volvo clamped coupling was great - you could slide a bit of steel into the slot, reverse the bolts in their holes, and just jack the coupling open.

shaftcoupling.jpg

Photo from Vyv Cox's excellent website.
Click to expand...
The Yanmar coupling is exactly the same and I have used that method to remove mine. I now have the R&D version which uses through holes and nuts on the bolts so you can't reverse the screws to jack it open.
 
Got mine off in 5 mins with a puller, deep socket, and cordless impact. Hadn’t occurred to me to try the ‘long bolt method’…

However, the shine came off when I needed to get the socket off the puller - in anger, a few months later, when I next needed a deep 17mm ?
 
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