Topics

Elongated hole on conical coupling


svperegrinus@yahoo.com
 

Hello Craig and all others,

Many, many thanks for all the valuable input.

Regarding the possibility of the nuts coming loose, yesterday the Yanmar dealer told me they are creating "a washer" (via an outsourced turner).  I am sure there is a language barrier + my lack of mechanical engineering knowledge.

But if I understand correctly, this will be some sort of one disc that they will insert after the four nuts have been tightened, and this will prevent the four nuts from working themselves loose.

My main concern is that if the solution were so simple and obvious, why wouldn't the factory had implemented it?

Cheers,

Peregrinus
SM2K #350 (2002)


greatketch@...
 




---In amelyachtowners@..., <svperegrinus@...> wrote :

Hello Craig and all others,

Many, many thanks for all the valuable input.

Regarding the possibility of the nuts coming loose, yesterday the Yanmar dealer told me they are creating "a washer" (via an outsourced turner).  I am sure there is a language barrier + my lack of mechanical engineering knowledge.

But if I understand correctly, this will be some sort of one disc that they will insert after the four nuts have been tightened, and this will prevent the four nuts from working themselves loose.

My main concern is that if the solution were so simple and obvious, why wouldn't the factory had implemented it?

Cheers,

Peregrinus
SM2K #350 (2002)


greatketch@...
 

I do not know what the factory originally did on my boat.  Those bolts have been pulled out and reinstalled several times with the installation of new engine mounts, alignments and other maintenance procedures. If somebody was paying attention to details (and Harmonie's previous owners were very good at that) they replaced at least the washers, and likely the nuts and bolts each time. They may, or may not, have been put back in the original configuration.

I do not understand exactly what your local dealer is proposing to do, but there are a great many good solutions to keeping these connections tight.  There could be long arguments about which is the "best," but there are many solutions that I'd be happy with, probably including some I haven't seen before.  

Remember, pretty much every boat has a connection like this between prop shaft and transmission.  Keeping them connected is not a new problem, or one unique to the Amel drive train.  In fact, you could make a good argument that the Amel C-Drive presents a much easier problem because the loads are lower and more controlled than with a standard prop shaft.

If you put these bolts on your regular maintenance schedule and check them for tightness after the first 10 hours, and after that at least every 50 to 100 engine hours, you'll be good to go.

Bill Kinney
SM160, Harmonie
Annapolis, MD, USA


---In amelyachtowners@..., <svperegrinus@...> wrote :

Hello Craig and all others,

Many, many thanks for all the valuable input.

Regarding the possibility of the nuts coming loose, yesterday the Yanmar dealer told me they are creating "a washer" (via an outsourced turner).  I am sure there is a language barrier + my lack of mechanical engineering knowledge.

But if I understand correctly, this will be some sort of one disc that they will insert after the four nuts have been tightened, and this will prevent the four nuts from working themselves loose.

My main concern is that if the solution were so simple and obvious, why wouldn't the factory had implemented it?

Cheers,

Peregrinus
SM2K #350 (2002)


Alan Leslie
 

This would be very useful to know about if / when it happens.
I just tightened all four bolts...they had loosened slightly over the last couple of months, not even 100 hrs of motoring since the last tightening session. 
What do others get in terms of hours ??
Cheers
Alan
Elyse SM437


Craig Briggs
 

Hi Alan,
100 hours seems way too short. What do the bolts have on them? (Regular nuts, with or without split/lock washers and flat washers, Nylocs, Loctite ?)

My orignal Amel installarion had bolts with a small diameter L shaped rod welded to each bolt head, that went into the adjacent (extra) hole on the Vetus dampner housing and that prevented rotation when tightening the nuts - very handy. It then used flat washers and lock washers on the nut end and a conventional nut (not nylock). They never loosened.

Over the years I've switched to just nylocs and have had no loosening now for the 500 hours since I last pulled the engine, at which time it was still tight from the engine pull before that.

Cheers, Craig SN68


---In amelyachtowners@..., <divanz620@...> wrote :

This would be very useful to know about if / when it happens.
I just tightened all four bolts...they had loosened slightly over the last couple of months, not even 100 hrs of motoring since the last tightening session. 
What do others get in terms of hours ??
Cheers
Alan
Elyse SM437


Alan Leslie
 

Hi Craig

They were not "loose" but I could take up about a sixth of a turn on each.

Nyloc nuts, washer, no Loctite...I might do that.

Cheers
Alan
Elyse SM437
Bound for Vanuatu


Craig Briggs
 

Hii Alan,
I wonder if that might be normal-ish compression of the rubber shocks inside the Vetus. Frankly doesn't sound like a big deal and I should think the Nylocs would be ok without Loctite. The problem ones I've seen (and had) were really loose - like rattling around. Will be interesting to see how they are when next you inspect them.
Cheers, Craig


---In amelyachtowners@..., <divanz620@...> wrote :

Hi Craig

They were not "loose" but I could take up about a sixth of a turn on each.

Nyloc nuts, washer, no Loctite...I might do that.

Cheers
Alan
Elyse SM437
Bound for Vanuatu