carl hurth munchen, 947.10 gearbox

[kobbe]

hoping someone out there has a bit of knowledge of this box, I have been told by hurth they have no information on it as it was before their transition but when I try to engage fore or aft gears it seems the clutch is not engaging so has a resistance and grind, this started 2 weeks ago, I am hoping someone has some spares or even a gearbox lol, I seem to be banging my head up against a brick wall with this one, 

any help or advice would be gratefully received 

[RLWP]

Unless this gearbox is especially precious to you, your best bet is to replace it. It's rarely worth repairing the later Hurth/ZF boxes that you can get spares for

Richard

[kobbe]

thanks Richard, the problem I am faced with is lack of space and its married to a Peugeot 1.9 so not sure of anything small enough to replace it with, the box is about 8inch wide by about 6inch width, which does seem to be a issue, 

[RLWP]

Some pictures would help

Richard

[kobbe]

not sure if these are any help but space is a premium lol

[RLWP]

Being in focus would be a bonus...

What about in front of the engine and behind the sound deadening? What space is available if the engine needs to move?

Richard

[kobbe]

I could possibly get another 4 inches through moving the engine forward with extending the pipe work for cooling, I have a engineer who rebuilds gearboxes coming Thursday morning, I started the engine today and when I turned it off I heard what sounded like a hollow ching from the gearbox, the only way to describe it was like floating metal a bit like a damper spring sound on a car, sorry about the pics, they looked ok on my phone lol

[Tony Brooks]

Failed drive plate? No drive in either direction, grinding noise, ching from gearbox area.

[kobbe]

thanks tony but if I pull past the grinding it does both fore and aft gears, the boat actually moves but the gears appear to be trying to engage prior to the crunching ?? I would get the same if I tried putting my car into gear without pressing the clutch if that makes any sense, prior to this I would engage gear and only once I increased the revs would it engage 

regards keith

Edited November 7, 2017 by kobbe

[Tony Brooks]

I very much doubt your box actually moves gears to select a gear, in fact I have not seen a marine box that does. They use clutches and constant mesh gears. I suspect yours uses a pair of cone clutches. My BW7 Spanish ZF box uses multi-plate clutches but the same applies.

In some cases if a clutch is worn the two shaft speeds will not synchronise so if the final positive engagement is by dog clutch that would make a grinding noise but it is rare for both ahead and astern to fail at the same time.

I await with interest to see what the engineer comes up with.

[kobbe]

thankyou tony,as I say he is coming on Thursday so will keep you posted

[kobbe]

well the engineer arrived and thinks it could be a simple repair but will not know until he removes the gearbox to confirm, he suspects possible pressure plate, he is removing the gearbox Monday and will confirm. I will keep you posted 

[Tony Brooks]

Many thanks for  reporting back but:-

 

Pressure plate? !!!!!

I have not seen one of those on a boat   apart from on home modded petrol engines using a car gearbox.

The closest most boats get to one is the drive plate as per post 8.

It may be a slip of the tongue but keep a close eye, caution is now required before full trust is given.

Edited November 9, 2017 by Tony Brooks

[kobbe]

My apologies he did say drive plate, being a bit thick as I am lol

[Tony Brooks]

No need to apologise, it just indicates how much I trust the competence of a number of canal "engineers".

Drive plate, that's good. AS he said it should not cost too much, however if he gets the box off and then finds the plate is OK it may well cost a lot. He will not be able to say any more than he has until the box comes off.

[kobbe]

that's exactly the words he used, 

I did ask about and he and his father are well known locally, everyone who used them was happy and they live locally, the difficulty was them getting time as they are rather busy and the father has not been well, but time will tell and obviously I will keep you posted, just keeping my fingers crossed its only the drive plate, but he did mention it being no problem, am sure he mentioned r&d or something for a replacement, but may have got it totally wrong as I usually do lol

[Tony Brooks]

No, R&D do make drive plates for a range of engines. Sounds as if you may have found a sound chap.  If by chance the box itself is in trouble take heed of what Richard said earlier. Certainly with a more modern Hurths I would be sceptical about the long term prospects for a repair but yours may be different.

[kobbe]

thanks tony, he did say that himself, but will know more when the box is out, 

[kobbe]

hi tony, well the gearbox came out eventually, the engineer said it felt like it had never been apart since the day it was manufactured or fitted lol, to both of our suprises it has a centrifugal clutch system I think I remember him saying whilst laughing (photos attached) 

one of the shoe linings had slipped off and jammed behind the second shoe which is what was causing the problem, we have got the clutch manufacturers name still imprinted on it and they are still trading, (been in touch with them and awaiting a response) 

he spoke to his dad who had not seen that for a good few years so we all had a little chuckle, got to replace a seal on the box which after inspection looks damn good( his words not mine) 

thankyou for the chat and hopefully we will back up and running very soon, 

regards keith

[RLWP]

That's an unusual gearbox, thanks for posting the pictures

Richard

[kobbe]

its like the owner Richard lol, I must admit I feared the worst but consider myself very lucky 

keith

[Tony Brooks]

New one on me for marine use as well. Thanks for the update.

I now wonder what’s inside the box that needs a centrifugal clutch on the input. That's a rhetorical question unless anyone has a manual/drawings.

[kobbe]

When we opened the box (my quote) 

it looked like 2 shafts with 2 cogs one on each shaft and a arm with a shaft on which engages the gear, I should of asked the engineer to take pics lol

[Tony Brooks]

It sounds to me just like an old spur tooth sliding gear/sliding dog gearbox and that is what that clutch would imply. The good thing is that such a box should be very long lasting with no internal clutches to wear out. If the clutch was/is repairable then use to date shows that is also very long lasting. All I would say is that a very slow count to ten in neutral when going from ahead to astern would be a very good idea so it gives time for the engine speed to drop so the clutch disengages.

[kobbe]

I hope these are helpful 

Edited November 16, 2017 by kobbe