Gearbox and drive issues

[frogprints]

We recently had our gearbox replaced by RCR after the clutch went on the old Hurth. We upgraded to a Prm 120 on the recommendation of the engineer, who also suggested changing the ratio.

On my first cruise since fitting I noticed an increase in drive noise, low whine, and put this down to bedding in new components.

After about 20 hrs cruising when leaving a lock I heard a thump and the prop stopped driving forward or reverse. After mooring I checked the engine and the gearbox had disconnected from the engine!

The screws fixing to the mounting plate were out and the nuts on the flex coupling were also loose.

The engineer who fitted the box came out and asserted that there was no sign that the screws had come loose and that the driveplate required replacement. He informed RCR that the damage was caused by my hitting an underwater object - would I not have felt that? Before leaving the lock I had cleared a plastic bag from the prop and had not noticed anything wrong with the drivetrain at that point. Is this damage consistent we hitting an object sufficient to stop the prop dead but not be noticed by me? Has the engine whine any significance?

Your experienced views would be appreciated.

Incidentally the breakdown occurred in the "bandit country" between Rodley and Leeds and having endured hassle from the local yoofs I was not looking forward to ending more time marooned there. ?

Fortunately the CRT lockies, who were similarly concerned, were able to arrange a tow through the locks to Ridley, thanks again Anne and Garry on Ploddinon.?

[Guest]

Doesn't soumd right somehow. Can't see why bolts would come loose if you hit an underwater object? Did you get any photos/videos of the loose stuff?

Quite often "engineers" fail to renew nylock nuts, spring washers etc, which can cause such things to occur.

Edited July 10, 2015 by Guest

[frogprints]

Yes that was my thought to, the engineer pointed out that the screw heads were not scuffed, which would have occurred if they encountered the flywheel, and although not stretched they showed signs of pulling out of the aluminium at the end of the threads. However, if the gearbox moved away from the engine, which it would/did under the action of the prop, then this would also keep the screws away from the flywheel.

Tis certainly curious

[Neil Smith]

I would not be fobbed off by the so called engineer who fitted it, after 20 hours I would be looking for him to do all necessary repairs FOC as he probably never tightened the nuts/bolts enough or as previously stated fitted worn out nylocks, and hitting an under water object would not disconnect engine and box, who is he kidding or trying to wriggle out of.

 

Neil

[Bee]

Hitting an underwater object could certainly wreck the drive plate and lose all drive but loose nuts / bolts? not really although vibration can loosen things. Gearbox whine? any oil in it? new clear oil is difficult to see so look carefully. I am not that conversant with bell housings and different 'boxes and input / output shafts and flanges but I would check all of that just in case there is a mismatch.

Edited July 10, 2015 by Bee

[Bee]

Just re read your post, I wonder why he suggested changing the ratio? if it is only a fraction different from the Hurth that's neither here nor there but if its significantly different that is a very odd thing to do without a lot of calculations and knowing exactly what prop you have and more besides.

[nicknorman]

Hitting an underwater obstacle could conceivably shear the mounting studs, although that is highly improbable. However it most certainly could not cause the nuts to come loose. The latter could only occur as a result of inadequate fitting of the gearbox (nuts not fully tightened, worn nyloc, or prolonged excessive vibration from something out of alignment). So you are definitely being fobbed off. The gearbox will have come loose and moved away from the engine slowly over some time, and that is probably what damaged the drive plate.

 

Don't let that "engineer"* near it again.

 

* he is not an engineer, he is a mechanic, or technician if you like, and a bad one at that.

[Keeping Up]

Unfortunately this sounds typical of the "engineers" that RCR send out.

[AndrewIC]

I assume you are talking about the bolts that hold the gearbox onto the adapter plate, that you can't get at once the engine is back together? If so, something very similar happened to former boat neighbours of ours after they had a new engine fitted with the old gearbox reused. Those bolts need to be tightened as per spec torque, which is surprisingly low otherwise there is a risk of stripping the threads on the alloy gearbox, and should have loctite threadlock on them. I would suggest it is possible that either they were never tightened/thread locked properly (consistent with the coupling being loose as well), or possibly they were over tightened and the threads in the box stripped, and pulled out. (you would have to check the box to be sure). Hitting something underwater would I think be more likely to break the element in the drive plate, or shear something.

 

As far as running noise goes, I also replaced a failed Hurth with a PRM mechanical box (I say "I replaced", the work was actually done by that nice Mr Leech of this parish). Initially it was very rattly at low revs, until in conjunction with advice from Beta, Newage and R&D, all of whom were very helpful, I changed to a very soft drive plate. That replaced the rattle with a whine, which Newage said should go away after a "couple of hundred hours varied use" as the gears wore in. It seems to have done so.

[MtB]

Just re read your post, I wonder why he suggested changing the ratio?

 

 

 

I'd say that was because he had a gearbox with the wrong final drive lying about in his workshop and you looked like a great opportunity to get shot of it and invoice RCR for supplying.

 

How on earth would he know that the original final drive ratio was wrong anyway?

 

I smell a feckin' great rat.

 

Cynical? Moi??

Edited July 10, 2015 by Mike the Boilerman

[larkshall]

 

 

I'd say that was because he had a gearbox with the wrong final drive lying about in his workshop and you looked like a great opportunity to get shot of it and invoice RCR for supplying.

 

How on earth would he know that the original final drive ratio was wrong anyway?

 

I smell a feckin' great rat.

 

Cynical? Moi??

Methinks you are right crooked and a bodger. I would have thread locked the nuts.how do RCR RECRUIT THEIR BODGERS.

[nb Innisfree]

I think this thread should be locked...

[Tony Dunkley]

I think this thread should be locked...

 

It would probably be to the benefit of any future victims if the bloke who fitted frogprints gearbox was locked up instead.

[frangar]

I think this thread should be locked...

Really? Surely bad service should be noted as well as good service? I have to say whilst you only hear the bad experiences I have met more than one person who has had a less than positive experience with RCR contractors....and in one case I was there to witness.

 

Cheers

 

Gareth

[MtB]

Really? Surely bad service should be noted as well as good service? I have to say whilst you only hear the bad experiences I have met more than one person who has had a less than positive experience with RCR contractors....and in one case I was there to witness.

 

Cheers

 

Gareth

 

 

I think nb Innisfree was making a joke with his comment. A double entendre missed by most!

[nicknorman]

Really? Surely bad service should be noted as well as good service? I have to say whilst you only hear the bad experiences I have met more than one person who has had a less than positive experience with RCR contractors....and in one case I was there to witness.

Cheers

Gareth

I think it was a joke referencing the mentions of thread and locking!

[frangar]

Whoosh.........

 

Oh yes........that went right over my head!....whoops!.....been spending far too long on the NUG group on Facebook where such comments aren't unusual! .....please forgive me.....going to sit quietly in the corner now.......please ignore my comments!

 

Cheers

 

Gareth

[MtB]

Whoosh.........

 

Oh yes........that went right over my head!....whoops!.....been spending far too long on the NUG group on Facebook where such comments aren't unusual! .....please forgive me.....going to sit quietly in the corner now.......please ignore my comments!

 

Cheers

 

Gareth

 

 

Got a link to NUG, I've never managed to find it!

 

Can anyone join?

[frangar]

Got a link to NUG, I've never managed to find it!

 

Can anyone join?

Blimey you must be bored!

 

https://www.facebook.com/groups/narrowboatusers/

 

It's a public group so I don't even think you need anyone to verify you....Be warned....you will be ranting if you read too many posts! And if you disagree with anyone I hope you are aware that the world will end....

 

You have been warned!!

 

Cheers

 

Gareth

[Mrs Tawny Owl]

 

 

Got a link to NUG, I've never managed to find it!

 

Can anyone join?

 

NUG

National union of journalists who can't spell.

One of the more prominent members being BH Calcutta (failed), a very good friend of Boot the old English Sheepdog.

 

Anybody know what I'm talking about?

 

Sue

[Flyboy]

Blimey you must be bored!

 

https://www.facebook.com/groups/narrowboatusers/

 

It's a public group so I don't even think you need anyone to verify you....Be warned....you will be ranting if you read too many posts! And if you disagree with anyone I hope you are aware that the world will end....

 

You have been warned!!

 

Cheers

 

Gareth

Sounds like the perfect place for Tony Dunkley.

[nb Innisfree]

Whoosh.........

 

Oh yes........that went right over my head!....whoops!.....been spending far too long on the NUG group on Facebook where such comments aren't unusual! .....please forgive me.....going to sit quietly in the corner now.......please ignore my comments!

 

Cheers

 

Gareth

That's OK, I'll let it go this time...

 

 

I think nb Innisfree was making a joke with his comment. A double entendre missed by most!

Pathetic attempt at a joke more like.

[gazza]

 

NUG

National union of journalists who can't spell.

One of the more prominent members being BH Calcutta (failed), a very good friend of Boot the old English Sheepdog.

 

Anybody know what I'm talking about?

 

Sue

Richard and I discussed this a while ago

[Guest User]

.... The Perishers?

 

LCx

[Mrs Tawny Owl]

.... The Perishers?

 

LCx

 

Correct,

 

I've got collection of their annuals that I read again every few years when I want an innocent giggle.

 

 

Sue