Brum Tug belt drive problems

[Tony Brooks]

 

Good post, Mr Bizzard. It points to what I dimly remember when the engine was removed to fit the cutlass (not sure if that is the brand though) At this time the opposed plummer blocks were replaced. I will don the boiler suit and get on with it when I have finished my cup of tea.

 

I'll be back...

 

N

 

 

I can not help with the noise but if that cutlass is spelt Cutless than its a fluted rubber sleeve shaft bearing and as long a sit has water passing through the flutes the water lubricates the shaft bearing. Because the bearing is rubber with flutes along its length you will be able to lift the shaft in the bearing by compressing the rubber. I would say 2mm lift is a bit more than when new but little to worry about.

 

In an earlier post you talked about bronze. The rubber is carried in a brass or bronze sleeve but you should not have any plain metal bearings in a setup that uses Cutless bearings. Some applications use a plain bronze bearing at the gland end but these are usually fitted with a grease cup. If there is no method of greasing then you should only have Cutless shaft bearings and I would argue that plumber blocks should be used to isolate the shaft bearings form the lateral strain caused by the belt drive.

[nebulae]

I had a similar problem .I had fitted a Python Drive,which takes prop thrust on a (non tapered)bearing. After very few hours I had a sqeak .Could not believe it was the Python Drive,so tried everything else .Eventualy removed the thrust bearing which ran cleanly when turned in my hand .Fitted new bearing anyway. Problem solved .So,if in doubt,replace bearings. .Not familiar with the set up on your boat,have you got to strip the pulley off the output shaft to change the taper thrust bearings?

[Theo]

 

 

 

I can not help with the noise but if that cutlass is spelt Cutless than its a fluted rubber sleeve shaft bearing and as long a sit has water passing through the flutes the water lubricates the shaft bearing. Because the bearing is rubber with flutes along its length you will be able to lift the shaft in the bearing by compressing the rubber. I would say 2mm lift is a bit more than when new but little to worry about.

 

In an earlier post you talked about bronze. The rubber is carried in a brass or bronze sleeve but you should not have any plain metal bearings in a setup that uses Cutless bearings. Some applications use a plain bronze bearing at the gland end but these are usually fitted with a grease cup. If there is no method of greasing then you should only have Cutless shaft bearings and I would argue that plumber blocks should be used to isolate the shaft bearings form the lateral strain caused by the belt drive.

 

 

I believe that the arrangement is as it should be but I really need to do diagram of the arrangement to show what is there. I have quite a bit to do today while we are waiting for the lock (open at 4pm) so I might not be back with the diagram today. But you never know.

[Theo]

I had a similar problem .I had fitted a Python Drive,which takes prop thrust on a (non tapered)bearing. After very few hours I had a sqeak .Could not believe it was the Python Drive,so tried everything else .Eventualy removed the thrust bearing which ran cleanly when turned in my hand .Fitted new bearing anyway. Problem solved .So,if in doubt,replace bearings. .Not familiar with the set up on your boat,have you got to strip the pulley off the output shaft to change the taper thrust bearings?

 

Thanks for that. It all adds to the data and second hand experience that I am gathering. The gearbox shaft bearings that I now know are wrong I will replace as soon as I have asked the right questions. The thrust block is a bit further down the line.

 

N

 

Nick

[Theo]

Thought I would do the diagram before anything else:

 

https://www.dropbox.com/s/x59jael3elrcca4/Prop%20s.jpg?dl=0

 

Forgive the DB link.

 

N

Edited April 29, 2016 by Theo

[Keith M]

There should be a beaning on the left hand side of the pulleys as mention in post 6

 

If the belts are over tighten the shaft will bend slightly

 

Keith

[Stilllearning]

There should be a beaning on the left hand side of the pulleys as mention in post 6

 

If the belts are over tighten the shaft will bend slightly

 

Keith

I agree, as long ago I used my cousin's brumtug (no. 13 I think), and had to have a bearing added there to stop shaft wear and bending.

[bizzard]

Though I would do the diagram before anything else:

 

https://www.dropbox.com/s/x59jael3elrcca4/Prop%20s.jpg?dl=0

 

Forgive the DB link.

 

N

Is that the plummer thrust block that you discovered is faulty? Personally I would have preferred a plummer block on either side of the pulley block to save the stern bearing from taking some of the lateral stress. The bearings in that thrust block are probably back to back Timken tapered roller bearings which should take the propeller thrust as well as the lateral heave of the drive belts, BUT unless the Timken bearings in the thrust block are self centreing in the casting the slight lateral movement of the shaft in the stern tube will put an undue sort of awkward complex angular strain on it. Timken tapered roller bearings are adjusted with no play between the pair, in fact a very slight pre-load. A great many vehicles use twin back to back or face to face tapered roller bearings for their wheel bearings.

Edited April 21, 2016 by bizzard

[Keith M]

Is that the plummer thrust block that you discovered is faulty? Personally I would have preferred a plummer block on either side of the pulley block to save the stern bearing from taking some of the lateral stress. The bearings in that thrust block are probably back to back Timken tapered roller bearings which should take the propeller thrust as well as the lateral heave of the drive belts, BUT unless the Timken bearings in the thrust block are self centreing in the casting the slight lateral movement of the shaft in the stern tube will put an undue sort of awkward complex angular strain on it. Timken tapered roller bearings are adjusted with no play between the pair, in fact a very slight pre-load. A great many vehicles use twin back to back or face to face tapered roller bearings for their wheel bearings.

 

All of theinstall that I completed were back to back taper roller bearings

Later vessels had a second plummer mounted on the other side of the pulley

 

Keith

[bizzard]

 

All of theinstall that I completed were back to back taper roller bearings

Later vessels had a second plummer mounted on the other side of the pulley

 

Keith

Yes much better engineering, but makes it more difficult to change the belts, but hey-ho.

[Tony Brooks]

Though I would do the diagram before anything else:

 

https://www.dropbox.com/s/x59jael3elrcca4/Prop%20s.jpg?dl=0

 

Forgive the DB link.

 

N

 

Well that diagram calls into question exactly what the "cutless" is. In that position it would be a stern gland but I have never come across one marketed as Cutless or Cutlass before although that does not mean there are none.

 

In the long term I think a photo may help get a positive identification.

 

Almost certainly a water lubricated gland will be paired with Cutless bearings in the tube and unless there is a water feed/air bleed at the front of the tube the rubber bearings can run dry and when they do they can definitely squeak. I do not see how a bronze bush will give good service if it is only water lubricated so think whatever is ta the back end is probably not a bush as such.

Edited April 21, 2016 by Tony Brooks

[Stilllearning]

Have you tried methodically giving each part of the drive train a quick spray of WD40, one part at a time? When the noise stops you will have found the offending part.

[Theo]

There should be a beaning on the left hand side of the pulleys as mention in post 6

 

If the belts are over tighten the shaft will bend slightly

 

Keith

I agree absolutely in terms of the forces that are to be met. It does, however make belt replacement rather easier. It is not currently my intention to retrofit the said bearing. I will see how it all goes.

Have you tried methodically giving each part of the drive train a quick spray of WD40, one part at a time? When the noise stops you will have found the offending part.

 

No I haven't. That would have been a good quick idea!

[Theo]

Well that diagram calls into question exactly what the "cutless" is. In that position it would be a stern gland but I have never come across one marketed as Cutless or Cutlass before although that does not mean there are none.

 

In the long term I think a photo may help get a positive identification.

 

Almost certainly a water lubricated gland will be paired with Cutless bearings in the tube and unless there is a water feed/air bleed at the front of

There is. Just didn't put it on the diagram.

 

Is that the plummer thrust block that you discovered is faulty?

No. The faulty bearing(s?) is (are?) on the gearbox output shaft.

 

Personally I would have preferred a plummer block on either side of the pulley block to save the stern bearing from taking some of the lateral stress. The bearings in that thrust block are probably back to back Timken tapered roller bearings which should take the propeller thrust as well as the lateral heave of the drive belts, BUT unless the Timken bearings in the thrust block are self centreing in the casting the slight lateral movement of the shaft in the stern tube will put an undue sort of awkward complex angular strain on it. Timken tapered roller bearings are adjusted with no play between the pair, in fact a very slight pre-load. A great many vehicles use twin back to back or face to face tapered roller bearings for their wheel bearings.

 

I can certainly see that but it would require considerable expenditure to correct this. It seems to have been "good enough" since 1983 and with care and my new found knowledge it terms of inspection and noticing early impending problems I would guess that I can persuade it to last as log as I need it.

 

 

the tube the rubber bearings can run dry and when they do they can definitely squeak. I do not see how a bronze bush will give good service if it is only water lubricated so think whatever is ta the back end is probably not a bush as such.

 

I misunderstood your post and thought that you named the stern gland "Cutless" so forget the name and just call it a water lubricated stern gland. I dropped the instruction leaflet in the bilges after it had been fitted and now can't remember the brand. I will have a look in other files to see if I detailed it in the boat accounts when I get around to it and if I remember.

 

Edited April 21, 2016 by Theo

[Theo]

Off to try the temporary repair out. The lock's operational.

Nick

Edited April 21, 2016 by Theo

[Tony Brooks]

If the stern gland has a steel rotor like a very thick washer spinning round on the shaft the it uses a carbon ring seal. I think these may squeak if they are such a good seal no water can get to the faces. When car water pumps with the same type of seal did it we sued to put soft soap into the radiator. With this type of seal you can usually push the rubber boot back, away from the rotor and allow water onto the seal. If its this type try dripping some washing up liquid onto the seal. (Thus would be a PSS type).

 

Early Volvo seals (and maybe modern ones) work on a similar principle but with what looks like a Paxalon ring spinning with the rubber boot and bearing onto the end of the stern gland. Try the same but push the boot forwards.

 

Both types have a set compression distance on the rubber boot.

 

The more likely one is the Vetus gland but they use lip seals. They do however require regular lubrication and according to Vetus regular (every few hundred hours) stripping to clean scale form the shaft and re-lubrication. Someone will be along soon to say this is not required, just squirt some silicon grease into the gland.

 

There are other water lubricated seals like Deep Sea Seals but I have no experience of them.

[Theo]

 

 

The nasty noise has gone and is not there after 45 mins cruising. It looks as if all this worry was for the sake of a grease gun!

 

The bearings will be damaged and I will take AdrianH's advice in post #23 and replace them. I imagine that I can do this by unbolting the bearings and the sacrificial coupling (see photo). My uneducated assessment is that as long as replace all the shims exactly as they were there will be no problem of alignment. Do tell me if I am wrong.

 

I now need to source replacement bearings. If you know off the top of your head where I can get them close to the canal, could you tell me. I will Google it if not using the search term "bearing suppliers."

 

I will also need to know what to ask for. I think that there are some codes cast into the bearing shells. Will they do?

 

Thanks for all the advice, chaps. All of it added to my knowledge and focussed my thoughts.

 

Nick

 

Photo: https://www.dropbox.com/s/s9fvd0fd7u1tjtn/SAM_0123.JPG?dl=0

Edited April 21, 2016 by Theo
add a bit

[Ray T]

Nick, if you don't mind not moving for a bit RLWP can replace the inserts without having to change the whole thing. He did for me.

 

 

 

 

[gazza]

The bearing housing and insert will have numbers on them that will identify the insert you require.

 

As for a supplier Google bearing supplier and your current location and you will get somewhere near

[David Mack]

Adrianh post #23

 

The nasty noise has gone and is not there after 45 mins cruising. It looks as if all this worry was for the sake of a grease gun!

 

The bearings will be damaged and I will take AdrianH's advice in post #23 and replace them. I imagine that I can do this by unbolting the bearings and the sacrificial coupling (see photo). My uneducated assessment is that as long as replace all the shims exactly as they were there will be no problem of alignment. Do tell me if I am wrong.

 

I now need to source replacement bearings. If you know off the top of your head where I can get them close to the canal, could you tell me. I will Google it if not using the search term "bearing suppliers."

 

I will also need to know what to ask for. I think that there are some codes cast into the bearing shells. Will they do?

 

Thanks for all the advice, chaps. All of it added to my knowledge and focussed my thoughts.

 

Nick

 

Photo: https://www.dropbox.com/s/s9fvd0fd7u1tjtn/SAM_0123.JPG?dl=0

 

What is 'sacrificial' about the coupling?

 

http://www.bearingboys.co.uk ought to have what you need.

[gazza]

 

What is 'sacrificial' about the coupling?

 

http://www.bearingboys.co.uk ought to have what you need.

Nothing, it looks to be a R&D coupling on a bog standard shaft coupling.

[David Mack]

Nothing, it looks to be a R&D coupling on a bog standard shaft coupling.

 

That's what I thought.

 

I wonder how well aligned the shaft is with the gearbox output shaft. Misalignment could contribute to noise and vibration, and degradation of the bearings.

[gazza]

 

That's what I thought.

 

I wonder how well aligned the shaft is with the gearbox output shaft. Misalignment could contribute to noise and vibration, and degradation of the bearings.

R&D couplings are a piece of cake to line up. One bolt head is turned down to a bit of a tit in the centre. A clutch of feeler gauges measuring between tit and flange at 12,3,6 & 9 o'clock make it a very quick operation indeed.

If I recall it will accept misalignment of 0.25mm quite happily.

 

Why narrow boat builders don't use skf type spherical roller thrust bearings I'll never know.

Still, the R&D will take thrust loads and there won't be much left once loses thru the pulleys are accounted for.

 

I wonder what type of bearing supports the end of the prop shaft?

Edited April 21, 2016 by gazza

[Theo]

What is 'sacrificial' about the coupling?

 

http://www.bearingboys.co.uk ought to have what you need.

It is a plastic arrangement which connects the gearbox output with a further short shaft. It is there to protect the gearbox and crankshaft from damage in the event of a sudden obstruction to the propeller.

 

That's what I thought.

 

I wonder how well aligned the shaft is with the gearbox output shaft. Misalignment could contribute to noise and vibration, and degradation of the bearings.

 

I suppose that as unbolt the bearings they with move to their unstressed positions. I will then have to add (or remove shims until there is no stress when I tighten up the bolts again.

[David Mack]

It is a plastic arrangement which connects the gearbox output with a further short shaft. It is there to protect the gearbox and crankshaft from damage in the event of a sudden obstruction to the propeller.

But its not really sacrificial, just resilient, to accommodate engine movement on flexible mounts, a degree of misalignment and to reduce noise transmission from the engine to the hull. With rubber belts between the engine and the prop shaft you already have much more protection against shock loading than a conventional transmission.