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bizzard

shaft coupling

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A little cheap wheeze for coupling gearbox half coupling to shaft half coupling.

To fit all Lister LH150 and manual gearbox's or reduction gear half couplings.

And perhaps others with 6 bolt connection and the same dimentions.

If your engine is mounted solid as mine is ''Lister ST. And can create a two inch or so gap between the above two couplings,a Ford Granada Mk1 or 2 prop shaft rubber doughnut as fitted to these cars to smooth the drive to the rear differential to make smoother clutch operation and to prevent the sudden kick which the rear axle would receive . Make your prop doesn't stick out of the back more than one and a half times the diameter of the prop shaft though.

Mine has been installed now for 11 years and absolutely trouble free,thrust movement for and aft only minimal.

They can still be bought at motor factors QH or Unipart for £13 or so.

I am also apalled at the modern way in which engine and transmission are fitted to canal boats ie engine stuffed right up the back,rubber mounted with no double uj's and and thrust block to take for and aft thrust off the mounts and yanking the stern tube all over the place and causing premature failure.

Stern tube assembly kept maintained greased and packed properly should last the life of the boat 30 years or so.

In my experience. If the engines put at the extreme rear to enlarge accomodation, and no room for proper twin uj's and thrust block there's absolutely no alternative than to solid mount,and align with dial gauge and feeler gauges. A little more vibration but wow no more constant expense ect. In my humble opinion.

Bizzard.

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Sounds like a good idea.

 

Any chance of some piccies ?

 

 

 

If needed host them on Flikr or WHY and link to this post.

Edited by jake_crew

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Shaft coupling ? Is this the 'swingers' thread ? :blink:

No, i have an electric starter i don't use a handle.

I'll have to sort out how to send pics. Computers are not really my thing just useful sometimes.

The Ford Granada prop shaft rubber doughnut has 6 equidistant bolt holes around its circumferance so 3 bolts go into the gearbox or reduction gear coupling and 3 the other way into the propshaft coupling. with some washers to space them a little.

The doughnuts are solid metalastic units with the 6 bolt holes with moulded in steel inserts, Obviously they're tough and could absorb the power from an 3litre or so of car engine. I'm sure someone on the forum could provide a picture of one. Any old ex mechanic like myself will know them intimately as they had to be removed to remove the cars gear box to renew its clutch ect.

bizzard.

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The R+D I've got on my two ST2s with LH150s, is a simple hard rubber disc of this sort. Not there to reduce shock loads, but to be sacrificial in the case of something dramatic affecting the prop...

 

PC

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The R+D I've got on my two ST2s with LH150s, is a simple hard rubber disc of this sort. Not there to reduce shock loads, but to be sacrificial in the case of something dramatic affecting the prop...

 

PC

Yes they're very similar and will absorb a bit of shock and prevent some shaft to hull vibration.

bizzard

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I am also apalled at the modern way in which engine and transmission are fitted to canal boats ie engine stuffed right up the back,rubber mounted with no double uj's and and thrust block to take for and aft thrust off the mounts and yanking the stern tube all over the place and causing premature failure.

Stern tube assembly kept maintained greased and packed properly should last the life of the boat 30 years or so.

In my experience. If the engines put at the extreme rear to enlarge accomodation, and no room for proper twin uj's and thrust block there's absolutely no alternative than to solid mount,and align with dial gauge and feeler gauges. A little more vibration but wow no more constant expense ect. In my humble opinion.

Bizzard.

 

Aquadrive or PythonDrive cures this situation, thrust bearing and twin CV joints neatly contained in a short length.

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Aquadrive or PythonDrive cures this situation, thrust bearing and twin CV joints neatly contained in a short length.

yes i agree,but often on modern boats there's not enough room to move the engine further forward to accomodate that sort of set up.And nearly all modern boats are engined in this dodgy manner ie Rubber mounted engines threshing around with one perhaps centreflex coupling to cope and no seperate thrust block to take the for and aft load off the engine mountings. I've recently had to replace sterntube bearings on two widebeam boats and adjust and realign engine and the boats were only 3 years old. 25 to 30 tons being shoved along by 4 small squares of rubber,absurd!

I've noticed that on hire or ex-hire boats the jobs done usually properly aquadrive and thrust or similar for fear of being called out by their customers having broken down. In my opinion the engine should be solid mounted and aligned by dial gauge and feeler gauge,in the event of there not being enough room for U J's and seperate thrust block or Aquadrive type of units.

bizzard

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yes i agree,but often on modern boats there's not enough room to move the engine further forward to accomodate that sort of set up.And nearly all modern boats are engined in this dodgy manner ie Rubber mounted engines threshing around with one perhaps centreflex coupling to cope and no seperate thrust block to take the for and aft load off the engine mountings. I've recently had to replace sterntube bearings on two widebeam boats and adjust and realign engine and the boats were only 3 years old. 25 to 30 tons being shoved along by 4 small squares of rubber,absurd!

I've noticed that on hire or ex-hire boats the jobs done usually properly aquadrive and thrust or similar for fear of being called out by their customers having broken down. In my opinion the engine should be solid mounted and aligned by dial gauge and feeler gauge,in the event of there not being enough room for U J's and seperate thrust block or Aquadrive type of units.

bizzard

 

I absolutely agree with your assessement. This piccie shows my compromise setup (its not actually my setup but its the same), a Centaflex and Plummer Block Bearing;

 

med_gallery_6875_570_67488.jpg

 

I have spoken to a couple of non-boating engineers and they were horrified at the idea of attaching a flexibly mounted motor to a solid shaft and bearing without a couple of universal joints in between. They both said that a Centaflex without a thrust bearing is not good enough and with a thrust bearing is a poor compromise!

 

Regards

Ditchdabbler

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I absolutely agree with your assessement. This piccie shows my compromise setup (its not actually my setup but its the same), a Centaflex and Plummer Block Bearing;

 

med_gallery_6875_570_67488.jpg

 

I have spoken to a couple of non-boating engineers and they were horrified at the idea of attaching a flexibly mounted motor to a solid shaft and bearing without a couple of universal joints in between. They both said that a Centaflex without a thrust bearing is not good enough and with a thrust bearing is a poor compromise!

 

Regards

Ditchdabbler

I seem to recall that Centaflex say that their unit should always be fitted with a pillow block bearing. I have seen many without. One where I had to tackle a permanently leaking stern gland turned out to have lost nearly 20% of the shaft diameter inside the gland because of shaft throw.

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I absolutely agree with your assessement. This piccie shows my compromise setup (its not actually my setup but its the same), a Centaflex and Plummer Block Bearing;

 

med_gallery_6875_570_67488.jpg

 

I have spoken to a couple of non-boating engineers and they were horrified at the idea of attaching a flexibly mounted motor to a solid shaft and bearing without a couple of universal joints in between. They both said that a Centaflex without a thrust bearing is not good enough and with a thrust bearing is a poor compromise!

 

Regards

Ditchdabbler

They are quite right as that particular centaflex unit only copes with a small amount of movement,you will now preserve your sterntube bearings but your rear gearbox bearings are under more stress. will the engine move forward more to accomodate the longer double centaflex coupling? if not make sure your engine mounts are always in good nick and check for misalignment now and again. bizzard.

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I seem to recall that Centaflex say that their unit should always be fitted with a pillow block bearing. I have seen many without. One where I had to tackle a permanently leaking stern gland turned out to have lost nearly 20% of the shaft diameter inside the gland because of shaft throw.

me to, dodgy space saving dodges in order to increase the accomodation size, it wouldn't be allowed on a sea going boat for obvious safety reasons.

One of the boats i've recently repaired had to have new engine mounts,new propshaft and complete sterntube assembly, but no room to move engine further forward to do the job properly.The boat was only 4 years old with about 700 hrs on the clock

regards bizzard.

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yes i agree,but often on modern boats there's not enough room to move the engine further forward to accomodate that sort of set up.And nearly all modern boats are engined in this dodgy manner ie Rubber mounted engines threshing around with one perhaps centreflex coupling to cope and no seperate thrust block to take the for and aft load off the engine mountings. I've recently had to replace sterntube bearings on two widebeam boats and adjust and realign engine and the boats were only 3 years old. 25 to 30 tons being shoved along by 4 small squares of rubber,absurd!

I've noticed that on hire or ex-hire boats the jobs done usually properly aquadrive and thrust or similar for fear of being called out by their customers having broken down. In my opinion the engine should be solid mounted and aligned by dial gauge and feeler gauge,in the event of there not being enough room for U J's and seperate thrust block or Aquadrive type of units.

bizzard

 

I agree, since fitting a new flexibly mounted engine complete with a Python Drive over 3k engine hours ago we never need to adjust our stern gland and never a drop of water.

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