Help! Prop shaft extraction

[chas]

I have to change the rubber gaiter between my stuffing box and the hull, so have to extract the inboard end of the prop shaft from its connection with the gearbox, a job I have not done before. This is what it looks like:

The other side looks like this:

There was a bolt in the hole. It came out very easily and was not done up tight. There is no split in the housing, so it is not a clamping arrangement. There looks as if there is a pin through the prop shaft, but I cannot move it. Before I smash the whole thing up with a maul, does anyone recognise the arrangement? Can you tell me what I should do?

very many thanks in anticipation

 

[vyv_cox]

All the ones I have seen without a housing split have a small groove machined in the shaft. The bolt hole is drilled just inside the diameter of the shaft and locates in the groove, providing axial and torsional fixing.

The pin(s) is new to me and I don't see the need for it in view of the bolt. Try drawing the coupling flange off the shaft by loosening the two nuts and putting a nut or something against the shaft end, then tighten the nuts carefully. The flange may be drawn off the shaft but if not it could be that the pin goes right through. In that case don't hammer it, you will damage the output bearing in the gearbox. Press it out with something, a G-cramp might do it.

 

[doug748]

Looks like a taper pin to me. Give it a blast with WD40 (or diesel or parafin) and leave it for as long as you can spare. If you can build a moat of putty and leave the fluid for a day,or more, so much the better. Do this from both sides if you can. When you belt it, support the clamp with a heavy weight from the rear. This is vital, both to protect your gearbox and to give you a decent chance of moving it.

 

[scottie]

the pin will most likely be tapered and should knock out from smaller end
its
worth supporting the coupling when doing this

then disconnect the coupling from gearbox and pull off from shaft

 

[alan006]

I can't quite tell from the photos if the pin has been rounded over. If it has then it will not just pop out with a drift, you might have to drill it out.
Once you have got the pin out then slack off the two locknuts and put an old nut or simular object between the two flanges. Then do up the two nuts evenly such that the end of the shaft is forced by the packing nut out of its flange. The nut should be just smaller than the shaft area.
Good luck.

 

[wotayottie]

use a vernier on the pin to see if one end is thicker or one end has been peened. if the latter, dremel is your friend - just grind off the excess. the pin will have a taper or peening - how else would it have stayed in when new and shiny?

a trick taught to me by an old fitter and which has never failed with seized up mooring shackles. take two reasonable sized hammers and hit the flange fitting on opposite sides simultaneously. that should loosen any rusted up interface.

lots of heat (wet cloths to protect the hull) and patience. penetrating liquids are useless if the interface is bonded by rust. you first need to get some sort of crack in the join - then use penetrating oils.

 

[chas]

Thank you all for this. I must admit to being a little surprised, even concerned, that something so fundamental to my wellbeing (ie the propellor going round) is reliant on a pin which is not secured by anything other than friction - and is situated in what must be the centre of vibration!

 

[iangrant]

looks like the bolt was the thing stopping the shaft revolving and the pin is tapered as a locator.

As has been said lots of wd 40 etc... then support the other side and give it a tap - or try and get a pair of mole frips on it and give it a twist?

Applying a fair bit of heat on it may help but all in all it looks like one of those really grizzly tasks - dead kenns and scraped knuckle pic please..

Ian

 

[wotayottie]

[ QUOTE ]
dead kenns
Ian

[/ QUOTE ]

? Typo or interesting local dialect? /forums/images/graemlins/grin.gif

 

[iangrant]

oops type - for kenns read knees

 

[Norman_E]

A taper pin will not fall out if fitted properly, and provides a secure method of locating components in the correct alignment. The taper is very gradual, and is not therefore self releasing. The British Standard shaft key taper is 1/100, or very nearly 1/8 inch per foot. Any good engineers supplier will be able to provide a replacement taper pin once the old one has been removed, if it is rusted or otherwise damaged.

 

[ex-Gladys]

Plus gas is a much better peetrating fluid than WD40