Engine Tie Bar

[Evo]

And me...!!

 

This is hard work though....I cant think why taper rollers and angular contact bearings ever came about... std ball races are fine. They must be because Paul Catchpole uses one.

 

Come on, even cars dont have std ball races to cater for side loads...we are talking nearly all side/thrust load in a boat so why fit a bearing thats not designed for that. Plummer/pillow blocks are designed for things like roller tracks or any purely rotational industrial application with litle to no side loads. As soon as side/thrust loads are involved we move to angular contact balls or taper rollers.

 

Richard to begin with you hinted your BMC Midget/sprite/A35 wheels would fall of because it only had std races, now you're admitting it has angular contact. Lets forget that argument shall we. Cars moved to angular contact/taper roller years ago. BMW etc even had special one piece full width angular contact ball bearings made because they are frictionally superior to a pair of tapers.

 

So do we still think a std ball race should take all the load from our prop when better purposely designed bearings have been designed specifically for that application...??

 

Some folk like casper will buy a cheapo plummer block cos its a ready made bearing housing thats a piece of piss to bolt on, originally I'm guessing some canal engineer guy thought he'd save some wear and leaks on his bronze stern tube with an alignment/support bearing but its turned into ..ding ding ..use it for thrust aswell - probably by a lesser competent canal engineer.

Edited May 9, 2011 by Evo

[MoominPapa]

OK then experts, I have one of these plummer blocks and its a bit noisy after 20 years. What should I replace it with? I need something as close as possible to a bolt-on replacement. Forward of the bearing there's about 10 feet of lorry propshaft with a Hardy-Spicer joint at each end and a sliding joint, then a Lister reduction box complete with thrust bearing, not currently taking any thrust.....

 

 

MP.

[Timleech]

OK then experts, I have one of these plummer blocks and its a bit noisy after 20 years. What should I replace it with? I need something as close as possible to a bolt-on replacement. Forward of the bearing there's about 10 feet of lorry propshaft with a Hardy-Spicer joint at each end and a sliding joint, then a Lister reduction box complete with thrust bearing, not currently taking any thrust.....

 

 

MP.

 

If it's 'a bit noisy' after 20 years, replace it with another the same, why ever not if it's done the job for that long?. Make sure it's a 'proper' make, there are some el cheapo copies around.

 

Tim

[Evo]

Depends entirely on how much work you want to do and how much you want to spend.

If its been noisy for 18 of those 20 years I'd do something about it, if its only just started to be noisy and you would rather spend you're on something else, just replace it.

If its broken down because the boats use has changed I'd sort it out.

If you're going on holiday next week I'd just replace it.

If I had the time and a passion for getting things right I'd sort it.

 

As Tim said

If you replace the bearing dont buy a cheapo from ebay, get a good one, you will struggle with that if you dont go to a proper bearing place.

 

You cant transmit the load down your propshaft, the UJ's wont like it and the sliding joint knackers that anyway. So you're looking at Python or similar...big cash.

Edited May 9, 2011 by Evo

[Timleech]

Depends entirely on how much work you want to do and how much you want to spend.

If its been noisy for 18 of those 20 years I'd do something about it, if its only just started to be noisy and you would rather spend you're on something else, just replace it.

If its broken down because the boats use has changed I'd sort it out.

If you're going on holiday next week I'd just replace it.

If I had the time and a passion for getting things right I'd sort it.

 

As Tim said

If you replace the bearing dont buy a cheapo from ebay, get a good one, you will struggle with that if you dont go to a proper bearing place.

 

You cant transmit the load down your propshaft, the UJ's wont like it and the sliding joint knackers that anyway. So you're looking at Python or similar...big cash.

 

Oh yes you can! There are plenty of boats around which do exactly that, especially Narrow Boats with back cabins, where the long shaft under the cabin floor lends itself very well to that arrangement. Not with a sliding joint, obviously. You have to try to get a balance between having the joints going through enough of an angle that the needle bearings actually do move around, and a small enough angle that the thrust doesn't lead to vibration problems. In the real world, using generously sized joints and greasing them regularly is the answer.

 

The A35 bearings are indeed angular contact, but Paul's gearbox bearing isn't. It's a deep groove single row bearing (IIRC) and is designed to take end thrust. The Lister it is fitted to would normally take all the prop loads through that bearing

 

Richard

 

 

The thrust in the Lister box is taken on a special ball thrust race with a split inner, in effect an 'extra deep groove' bearing. These are the ones which don't like running with no thrust.

 

-but-

 

The Parsons mechanical boxes use a similar bearing, we needed a replacement in a hurry many years ago for one of the Hotel Boats and it was not available or only for very silly money (they're expensive at the best of times and mostly obsolete, you're at the mercy of whoever has stock).

The guy in Fenners suggested an ordinary deep groove race might do the job, so we looked up the specs. The thrust was well within its rating, the cost was peanuts compared with the 'real thing', so we gave it a try. That bearing was still doing its job perfectly well when the engine was taken out after at least 12 years regular hard work, though it has to be said the gearbox (Parsons F type) was on an engine (Armstrong AS2)well below its maximum capability.

 

Tim

[RLWP]

<snip>

 

So do we still think a std ball race should take all the load from our prop when better purposely designed bearings have been designed specifically for that application...??

 

<snip>

 

Yes! It's what single row ballraces do well. You seem to be getting confused with set-ups that need to eliminate end float and therefore use a pair of bearings. The one I keep mentioning is specifically installed in a marine gearbox, designed by Lister, to take the prop thrust in both forward and reverse. It's you who is being arrogant in insisting that it won't work and is somehow "wrong" in your judgement just because you are unfamiliar with this kind of bearing

 

Richard

[Evo]

Tim, of course a solid propshaft with UJ's would work - for a while. Its hardly good practice though is it..!!! I cant think of a single application where needle roller spider joints are used for thrust. Great care is made to make sure they dont take thrust - with sliding joint actually in the prop or on the gearbox output shaft.

 

Blimey oh Riley, fiddling about getting just enough out of alignment and constant maintenance of your spiders else bad vibration and premature failure surely tells you its a crap idea.

 

Yes I know there are lots of old boats with props under their back cabins, i dont care how many times its been done or why and how long some have lasted, its just plain wrong.

 

 

I didn't know about a special bearing fitted to some Lister gearbox or whatever but we are surely not advocating the guy change his engine and gearbox are we, and you guys are not desperate enough to keep finding the one posible time a deep groove ball has been used just to nit pick at me are you. I mean we are talking something that sounds like its rocking horse poo and wasn't a great suuccess anyway - else they'd be making them by the million still wouldn't they.

Edited May 9, 2011 by Evo

[RLWP]

<snip>

 

The guy in Fenners suggested an ordinary deep groove race might do the job, so we looked up the specs. The thrust was well within its rating,

 

<snip>

 

Tim

 

Tim, I think it's very unfair of you bringing actual, documented facts into this uninformed, opinionated discussion.

 

 

Richard

 

Tim, of course a solid propshaft with UJ's would work - for a while. Its hardly good practice though is it..!!! I cant think of a single application where needle roller spider joints are used for thrust. Great care is mnade to sure they dont take thrust - with sliding joint actually in the prop or on the gearbox output shaft.

 

Blimey oh Riley, fiddling about getting just enough out of alignment and constant maintenance of your spiders else bad vibration and premature failure surely tells you its a crap idea.

 

Yes I know there are lots of old boats with props under their back cabins, i dont care how many times its been done or why and how long some have lasted, its just plain wrong.

 

Gareth, sorry mate, I'm out. I'm afraid that I can't take your rants based on a bit of fiddling about and uninformed opinion seriously when you argue against someone like Tim with many years of actual, practical knowledge and experience. You are making yourself look a complete tit.

 

How's the IT contracting business?

 

Richard

[Evo]

Not that old cookie again Richard...I seem to have an awful lot more basic knowledge about these things than most. Maybe because I studied mechanical engineering and did a proper apprenticeship/degree at it. Switched to IT for more cash aged about 25.

 

An art student could see whats wrong here though...you dont really need much engineering savvy.

 

Tim knows its all wrong, but it requires radical changes to boats if its to be put right and customers probably aren't prepared to pay.

Guys with the old beauties want to keep it as it was - they dont want some shiny Python drive ruining the authenticity maybe.

 

Only one person being an uninformed, opinionated tit here Richard - sorry mate but you're upsetting yourself again based

on Canal Engineers crude bodger style methods aren't you.

Edited May 9, 2011 by Evo

[Timleech]

 

 

Tim knows its all wrong, but it requires radical changes to boats if its to be put right and customers probably aren't prepared to pay.

Guys with the old beauties want to keep it as it was - they dont want some shiny Python drive ruining the authenticity maybe.

 

 

No, I know it's usually said the UJs shouldn't carry thrust.

I also know that they can do so perfectly well, I've installed several that way myself and have many years of experience with maintaining boats which had UJs carrying thrust and which worked hard for their living.

It works, therefore why is it wrong?

 

Tim

[Evo]

So you know its not recommended but you still do it.!!..ever find out why its not recommended..??

 

Look you've both been contradicting yourselves to make an argument. Richards gone off with his arse in his hand - again.

 

Before this ends up another proper nut job.. I'm out too. Go google bearings and applications - its as easy as that.

[Timleech]

 

 

I didn't know about a special bearing fitted to some Lister gearbox or whatever but we are surely not advocating the guy change his engine and gearbox are we, and you guys are not desperate enough to keep finding the one posible time a deep groove ball has been used just to nit pick at me are you. I mean we are talking something that sounds like its rocking horse poo and wasn't a great suuccess anyway - else they'd be making them by the million still wouldn't they.

 

The split race ball bearing used to be absolutely normal fitment for marine gearboxes, to carry thrust as well as the radial load from the gears. Yes over time they've been superseded by other ways of doing it, such as pairs of tapered rollers, but in their day a lot of makers used them.

 

Tim

[Evo]

I dont know wether you noticed Tim...but didn't I say "we'd moved onto angular contact and taper rollers years ago". Its Besides the point anyway, what has an old obsolete split bearing got to do with this..? It was pathetic bringing them up as an example of ball bearings being used for thrust in the first place, we dont use them anymore, its hard to get them, and the OP certainly wouldn't be casting himself some special bearing carrier so he could fit one....if he could afford one that is.

 

Sometimes this place is a Joke...I've got you actually agreeing with me that plummer/pillow blocks are not the best things for thrust, I've got you acknowledging that you know spiders shouldn't be thrust loaded, I've got some half wit telling me I'm making opinionated guesses all the time making myself look a tit in the process - and all for the simplest of engineering practices.

 

My god some of you struggle with this stuff....no wonder theres so many bodged up boats.

[MoominPapa]

If it's 'a bit noisy' after 20 years, replace it with another the same, why ever not if it's done the job for that long?. Make sure it's a 'proper' make, there are some el cheapo copies around.

 

Tim

Ok, how do I align the new one? Or do I not need to? As far as I can see, the existing one is bolted to a chunk of angle-iron welded across the V of the swim. Side-to-side alignment is handled by oversize bolt-holes in the bearing housing. Do I need to shim it underneath to the up-and-down right?

 

MP.

[Chertsey]

I dont know wether you noticed Tim...but didn't I say "we'd moved onto angular contact and taper rollers years ago". Its Besides the point anyway, what has an old obsolete split bearing got to do with this..? It was pathetic bringing them up as an example of ball bearings being used for thrust in the first place, we dont use them anymore, its hard to get them, and the OP certainly wouldn't be casting himself some special bearing carrier so he could fit one....if he could afford one that is.

 

Sometimes this place is a Joke...I've got you actually agreeing with me that plummer/pillow blocks are not the best things for thrust, I've got you acknowledging that you know spiders shouldn't be thrust loaded, I've got some half wit telling me I'm making opinionated guesses all the time making myself look a tit in the process - and all for the simplest of engineering practices.

 

My god some of you struggle with this stuff....no wonder theres so many bodged up boats.

This smacks of 'it's all very well in practice, but does it work in theory?'

[tom_c]

i know of one application where the needle rollers in a universal joint transmit axial thrust, the rear driveshafts on jaguar rear suspension. the driveshaft acts as a suspension link as well. it transmits both torque to the rear wheels and also axial loads placed on it by the suspension. I think the Jaguar engineers knew what they were doing. Deep groove ball bearings can transmit limited amounts of axial thrust when compared to other types of bearings, but this is normally more than enough for most typical installations.one part of the engineering design process is to look at the lowest cost option that will work and give satisfactory bearing life, if this can be achieved by using a deep groove ball bearing then use it, if it requires the use of taper rollers, angular contact ball bearings or spherical roller bearings to give some tolerance of misalignment. the ball bearings which you see on parsons gearbox outputs is a 4 point contact bearing, it is basically a pair of angular contact ball bearings sharing a common outer race and balls. anyway back to the original topic, kelvin diesels had a stay bar from the cylinder to the hull side, i don't think i have ever seen one fitted though. a stay bar to stop movement of the engine and take propeller thrust could be used, it would need to have some form of ball joint on each end to allow the engine to move on its mountings. if the bar is made large enough it could take thrust in both directions without deforming, the mounting on the hull would need to be carefully made and installed.

hope this helps

Tom

[Evo]

Ok, how do I align the new one? Or do I not need to? As far as I can see, the existing one is bolted to a chunk of angle-iron welded across the V of the swim. Side-to-side alignment is handled by oversize bolt-holes in the bearing housing. Do I need to shim it underneath to the up-and-down right?

 

MP.

 

 

I assembled my block completely on the shaft...remember mine is not now taper locked to the shaft so the whole plummer block can be just pushed up and down the shaft....that sorts your for aft alignment.....all I have to do is position it opver the mounting holes and shim up so its not 'bending' down shaft as you do it up.

 

When mine was locked to the shaft I used to take the lid off the block and do up the locking ring after I'd done the above.

[Timleech]

the ball bearings which you see on parsons gearbox outputs is a 4 point contact bearing, it is basically a pair of angular contact ball bearings sharing a common outer race and balls.

 

Must admit I'd never thought of it in quite that way, but here's one from a Kelvin RG32 gearbox, 4.25" bore. I'd hate to have to buy it new now!

 

 

 

Tim

[casper ghost]

 

Some folk like casper will buy a cheapo plummer block cos its a ready made bearing housing thats a piece of piss to bolt on,

NO NO NO. Don't try to guess why I decided to buy something...

[David Mack]

Yes I know there are lots of old boats with props under their back cabins, i dont care how many times its been done or why and how long some have lasted, its just plain wrong.

 

Ever since there have been propellor driven boats, there have been rigidly mounted engines, with rigid shafts between the stern tube and the back of the gearbox (or back of the clutch for the likes of Bolinder semis which don't have a gearbox), all carefully lined up once the boat is afloat. Most don't have UJs or roller bearings or anything of that ilk - if you're lucky you might get a crude rubber coupling which accommodates a small degree of misalignment as the hull flexes under varying loading conditions. Its simple and it works.

 

And its not 'plain wrong'. Its just not the only way of doing it!

 

David

[tom_c]

hi Tim, a metric bearing around that size is nearly £600 +VAT!!!!!!!!

[Timleech]

hi Tim, a metric bearing around that size is nearly £600 +VAT!!!!!!!!

 

ISTR the replacement for that one was similar money, & it must be at least 12 years ago

I put a new double spherical roller thrust bearing in an old Reintjes box a few years ago, I think it was 5" bore but it was metric (cheaper than Imperial), came in its own wooden packing case, I got it for a 'very good' price of £850+VAT.

Glad it wasn't my money!

 

Tim

[tom_c]

the price of the bearings is quite scary, especially as i am missing most of a gearbox for my kromhout and i have got to make a gearbox for my lidan hot bulb!!!!! unless i make it direct reversing and just fit a clutch. i dont think my wife will let me spend that sort of money on a couple of bearings

[jake_crew]

Some marine gearboxes have no moving parts when in forward gear other than the input and output shafts.

 

These often rely on thrust from the prop as part of the actuation mechanism to hold them in gear.

 

I'd go for solid mounts (oak or elm) and some careful alignment.

Edited May 9, 2011 by jake_crew

[Timleech]

the price of the bearings is quite scary, especially as i am missing most of a gearbox for my kromhout and i have got to make a gearbox for my lidan hot bulb!!!!! unless i make it direct reversing and just fit a clutch. i dont think my wife will let me spend that sort of money on a couple of bearings

 

How big is the Lidan? What about a reversing prop? That's what a lot of the Scandinavian boats used with hot bulb engines. Not ideal for shallow canals, though!

 

Tim