Knocking Sterngear

[Liam]

We're currently out on the T&M, and are having a prob with the stern gear. The engine is in it's own engine room with a transit type shaft running to the back, where it meets what looks like a normal prop shaft.

 

The knocking is coming from the back somewhere, and it's like someone is tapping two windlasses together lightly (dink dink dink sort of). It's not all the time, it comes and goes but has been getting very slightly worse as we've been cruising.

 

Also, where the stern greaser pipe runs into the shaft, the bolts and the shaft itself are getting quite warm (nearly hot). We've checked the prop and all is clear and we've also been out and bought a grease gun and greased the shaft twice now.

 

Any suggestions!? ASAP as we're on holiday and currently moored up in the middle of stoke on trent

 

Cheers

 

Liam

[Canal Shop Man]

Have you checked the bolt tightness - at both ends? My boat used to slacken the bolts to the front coupling every few months. They don't need to be very loose, just enough to allow the coupling holes to move slightly and clonk.

 

I take it you haven't tightened up the stern tube packing plate too much. This would cause the heat (but not the noise . . .) You should be able to turn the shaft by hand fairly easily.

[John Orentas]

Hi Liam.

 

It sounds to me like two separate issues, if the stern tube is getting warm or hot it is as you suggest a lack of lubrication or the tube is too tight but that can only be a problem with a new s'tube and shaft.

 

The grease may be flowing the wrong way and not getting between the bearing surfaces, stop every 15 minutes, monitor the temperature and keep trying to get some grease into it. Try slackening the gland nuts and allow it to leak a bit, this will help cool and lubricate it. Don't let it get more that hand hot in an extreme case it could seize. If you get desparate pour water over it. I assume you are using proper stern tube grease.

 

 

 

The knocking - I assume there are Hardy-spicer type U/J's on the shaft the knocking may well be these and exaggerated by the extra stiffness of the shaft. Are there any grease nipples on then units, if not try to get some heavy oil into the 4 joints but I suspect if you sort the stern tube the knocking will go away.

 

Can't think of much else for now, If you are going through the tunnel arrange to follow someone who is prepared to give you a tow if the worst happens, don't tell the tunnel keepers they may not let you go through at all.

[Liam]

Well we did make it home without a problem.

 

The knocking only comes along once the boats been running for some time... like a good couple of hours... We followed your instructions John, and greased the joints, but we weren't able to find out if the knocking comes back after that, although we did run out to the water and elsan point. We're off for a longer cruise this weekend so will find out then probably!

 

The Stern tube is no longer getting hot, or even warm. The bolts were undone and the "brass collar thing" (?) was pulled back and then push close again this time fixing the bolts hand tight only. We left it running in gear on our moorings for around 30/45 mins before going for water as mentioned above. It doesn't leak water but it doesn't get hot either. I assume the rather warm gland was caused by us tightening everything up blindly when we heard the knocking.

 

And you're correct in assuming that we're using proper stern rube grease which gets turned a bit before every cruise.

 

We'll see how it goes... and thank you guys

[Liam]

Okay, we're half way there.

 

The Stern Tube is now only slightly getting a little warm after cruising for around 2 and a half hours on both Saturday and Sunday, so it looks as though that's sorted.

 

The shaft, however, is still knocking, making that noise again like "kloink, kloink, kloink". This had only just started happening when we were coming back onto the moorings, just before mooring up after a 2 and a half hour run. I lifted the boards, it's hard to tell exactly where it's coming from as it is a bit echoey down there and there's the noise of the engine and the shaft spinning anyway, but I think it's coming from imbetween the stern gland and the middle joint.

 

I've put some pictures on the net... starting from the stern gland and going through to the gearbox...

 

Any more info would be very much appreciated. Thanks..

 

 

http://www.cw.lkhnet.co.uk/images/sterngear/1.jpg

 

http://www.cw.lkhnet.co.uk/images/sterngear/2.jpg

 

http://www.cw.lkhnet.co.uk/images/sterngear/3.jpg

 

http://www.cw.lkhnet.co.uk/images/sterngear/4.jpg

 

http://www.cw.lkhnet.co.uk/images/sterngear/5.jpg

 

http://www.cw.lkhnet.co.uk/images/sterngear/6.jpg

[Silkhay]

 

The shaft, however, is still knocking, making that noise again like "kloink, kloink, kloink". This had only just started happening when we were coming back onto the moorings, just before mooring up after a 2 and a half hour run. I lifted the boards, it's hard to tell exactly where it's coming from as it is a bit echoey down there and there's the noise of the engine and the shaft spinning anyway, but I think it's coming from imbetween the stern gland and the middle joint.

 

Have you checked the Hardy Spicer type Universal joints for movement. Back when I used to crawl under cars for a hobby they were a constant source of knocking, it doesn't take much movement to sound 'orrible.

 

Good luck

Martin

[Liam]

Hi Silkhay,

 

You've just reminded me of something I meant to add, but forgot too...

 

Pic 3 above... when I grip the shaft and try and wobble it, in a certain position it'll move up and down. When you turn it through 180 degrees, it won't move up and down but it does move sideways. If you shake it enough, you can hear a faint knocking, which I think is pretty obviously where the noise is coming from on a much louder scale when the shaft is spinning at normal cruising speeds.

 

Might be a daft question I know, but I hold my hands up... I only know the very basics about this sort of stuff. Could you please point out the Hardy Splicer UJ's please?

[bottle]

Picture of the piece that will probably need replacing

 

Hi Liam

 

Being that Martin has logged off, I will try to answer for him , the hardy splicer are the joints

 

They look like two 'U' shaped castings one at ninety degrees to the other, your picture two shows the hardy splicer.

 

You will notice it has circlips

 

I believe, it can be replaced but the bearing face in the casting will have to be checked to make sure that the holes that the shafts fit in have not gone oval.

Edited August 21, 2006 by bottle

[Tommo]

Liam

 

Sounds very much like a worn Universal joint to me.

 

 

Tommo

[alan_fincher]

I've only just spotted the latest replies on this, since Liam posted his pictures.

 

It's not entirely obvious, (to me at least!) from the pictures, if the bearing that sits between the stern tube, and the "articulated" drive shaft with the Hardy-Spicer joints in, is just a bearing that the prop-shaft can move back and forwards through, or whether it is taking the load of the thrust from the propeller.

 

I rather suspect it ISN'T taking the force of the prop, and that this instead being transmitted through the whole drive train ? (So that the gearbox is taking the strain, and the whole shaft, including those spider joints is being put under compression when in forwards, or being "stretched" when in reverse).

 

I had a boat years back with similar arrangements, and although it all worked fine, I was told by several people "in the know", that Hardy-Spicer joints are not intended to take large forces in these "sideways directions", and will often wear out quickly as a result.

 

If this shaft originated in a road vehicle, then at one end I think it would go onto a splined drive that takes up movement resulting from the vehicles suspension, so there is generally no pulling or stretching force along the shaft. That is, it only has to transmit rotary motion.

 

Like the others, I suspect the joints are knocking. The above (rather garbled!) explanation might indicate why they are failing, and in an ideal world, I don't think these joints should really take forces along the line of the shaft

[John Orentas]

Hi Liam.

 

I too have only just spotted your photo's. I agree with Alan it doesn't look as though you have a thrust bearing which should be the first 'unit' after the stern tube. Although it is technically incorrect to transmit thrust through that type of u/j if they are in a reasonably straight line and in good condition there is no reason they can't cope. I imagine they have been ok for some time.

 

You can get new bearings for the older 'splittable' style of joints as these are as I can see the circlips that hold the bearing caps in place. The job is very easy to do if you can source them, they come complete with needle rollers.

 

Replacement will probably make everything quiet again for a few years.

 

P.s. Just seen Bottle's photo' that of course is the connecting component of Hardy Spicer. It may well be easier to replace the bearings one by one with the needle rollers held in place by grease.

[david and julie]

Liam you should get the parts from Serck/Woodhead RSR on Mellors Road in Trafford Park, opposite Brooke Bond.

You will struggle trying to do the job with the prop insitu as you really need to hold the unit in a vice to drift out the old bearings. In really bad cases I have had to burn the old unit in half to get them apart, they can be a real sod.

 

Seized UJ's can also make noises (creaking or squeaking) but don't always have play in them. The worst part is actually taking the prop off.

 

As an alternative you could take the full prop to North West Propshafts in Trafford Park and they will fit a any new UJ's and check it for balance afterwards.

 

Some of these joints have grease nipples and some are sealed for life. When sourcing the parts you may be able to get the former which I think are preferable.