Prop seized to propshaft

[MASH]

Vic is dead right about a new pin required regardless, but let's be sure it is the crown wheel moving on the shaft and not the shaft with wheel firmly attached moving in the bearing. I doubt that but...

There should be no movement whatsoever between wheel and shaft and the pin should be firmly in place. If it is the wheel sliding on the shaft pop the pin out and lets see how the wheel is keyed to the shaft. It sounds like the pin has sheared or partially sheared and is allowing the lateral force on the gear teeth to force the wheel to slide a mil or two down the shaft and out of mesh. The pin should come out with a pin punch or a suitable cut down nail as a drift.

Does the shaft slide in and out in it's bearing(s)?

 

[Pshaw]

New pin required obviously ! That should do it I think but maybe there should be a spacer where you indicate


What is it? A roll pin or spring pin.

I've no idea I'm afraid! How would I be able to tell?

Just wondering though if you were to just fit a new pin what stops the prop shaft c/w gear from pulling through the bearing .

Oh for a parts diagram!

Vic is dead right about a new pin required regardless, but let's be sure it is the crown wheel moving on the shaft and not the shaft with wheel firmly attached moving in the bearing. I doubt that but...

There should be no movement whatsoever between wheel and shaft and the pin should be firmly in place. If it is the wheel sliding on the shaft pop the pin out and lets see how the wheel is keyed to the shaft. It sounds like the pin has sheared or partially sheared and is allowing the lateral force on the gear teeth to force the wheel to slide a mil or two down the shaft and out of mesh. The pin should come out with a pin punch or a suitable cut down nail as a drift.

Does the shaft slide in and out in it's bearing(s)?

I'm not too sure - the pin was a mess, I've dug it out but the gear is still no easier to move - does not go any further down the shaft - the broken pin was making no difference.

I think the shaft may be tapered, so it can only come off the end with the prop on, which would be a right pain as that is completely seized to the shaft!

How easy would it be to replace the pin, if necessary? Shear pins seems to be fairly generic, is it the same with these gear pins?

Was thinking i'd try to hold the gear and shaft tight, and bang the prop torsionally with a rubber mallet to try and loosen it. I've left a lot of WD40 in it over the last few days, but it doesn't seem to have had a lot of effect.



For some reason I can only post one picture...will try again later!

 

[VicS]

How easy would it be to replace the pin, if necessary? Shear pins seems to be fairly generic, is it the same with these gear pins?

Was thinking i'd try to hold the gear and shaft tight, and bang the prop torsionally with a rubber mallet to try and loosen it. I've left a lot of WD40 in it over the last few days, but it doesn't seem to have had a lot of effect.

For some reason I can only post one picture...will try again later!

I'd be surprised if its on a taper. Should be easy to check the shaft diameter either side even by just looking at it.
Looking at your latest picture it looks like you have dug out the end bit of the pin but that the gear has turned on the shaft so the middle bit is still trapped in the shaft, out of sight.
I assume its not a grub screw. Is there a matching hole 180degrees round the gear.

Used all your space for pictures ?

 

[Pshaw]

I'd be surprised if its on a taper. Should be easy to check the shaft diameter either side even by just looking at it.
Looking at your latest picture it looks like you have dug out the end bit of the pin but that the gear has turned on the shaft so the middle bit is still trapped in the shaft, out of sight.
I assume its not a grub screw. Is there a matching hole 180degrees round the gear.

Used all your space for pictures ?

Ah yes, I'll measure either side but only have a ruler rather than calipers on me at the moment so it might not be too accurate...

I'll twist it and see if I can get any more out - there is a matching hole on the other side, too. There is also a marking on the shaft, which I'll photograph and put up.

How do I make more room for pictures?

 

[VicS]

How do I make more room for pictures?

by deleting some already thre.

Go to settings, then "my settings", then attachments.

It tells you how much space youve used and have left.

Select a few pictures you no longer need and delete them

I use Photobucket... I have enough space there to see me out!

 

[MASH]

Right, we're making progress. As there's a corresponding hole on the other side of the gear the pin is meant to go right through. What's happened is that it's sheared and the gear has either rotated or slid up the shaft, or both and is probably semi jammed on the remains of the pin that is still lodged in the hole thru the shaft. Like Vic I very much doubt it's on a taper. WhaT I would do now is to draw the gear off the shaft with a puller or find a way to support it on both sides and drive the shaft out of it. Then you can clean out the remains of the pin and find a replacement. I expect the gear is an interference fit on the shaft so it should come with moderate persuasion but desist if it really is stuck. Twisting it off could risk damaging the prop's shear pin or the prop itself, but again, might be worth a try.

It may be that when the pin sheared the lateral forces on the crown wheel pushed it up the shaft a little and lost the mesh - that's my guess. Once the wheel is relocated with a new pin it should all mesh up again. Unless some cowboy has assembled this up from bits before selling it to you I don't see how a washer/spacer could be missing with this sort of construction so fingers crossed that aspect isn't an issue!

How you'll find a replacement pin I don't know but these things must be standard sizes, I'd go begging with the bits in hand around a repair shop or two. It will be very satisfying to get this running again, won't it?

If a pin was hard to find I'd consider welding the crownwheel on as its an old engine. It'll never come apart again but so what?

Was the pin solid or was it a hollow split cylinder of spring-steel (a roll pin) - look it up on wikipedia. It's not a shear pin, this one is not designed to break under load. The shear pin is behind the prop and is there to protect this one and the other gear-locating/fixing pins from damage. Don't replace this with a shear pin! It is either a roll pin (slotted spring pin) or a solid hard steel pin.

edit. Might be possible to grip the crown wheel lightly in the vise between soft jaws or two scraps of plywood or leather so as to tap the shaft through with that plastic hammer - by far the easiest way if it will come.

 

[VicS]

Right, we're making progress.

The gear has to come off in order to extract the remains of the pin. The shape pretty much rules out an ordinary three legged gear puller, I think. Mine would not grip it. A press would be ideal. Maybe a small engineering workshop would do it without charging the earth..
As it moves sufficiently to lose the mesh its not stuck fast. its only likely to be the remains of the pin holding it I would think.

Never had to buy a pin but they do come in standard sizes .. probably in large numbers though so the difficulty might be in buying just one.

Id doubt if its a solid pin. If it is the ends will have to be peened over to stop it coming out again.

Likely as MASH says a split spring pin, ( roll pin),

Or maybe a coiled spring pin

On reflection not likely!

 

[Pshaw]

Right, we're making progress. As there's a corresponding hole on the other side of the gear the pin is meant to go right through. What's happened is that it's sheared and the gear has either rotated or slid up the shaft, or both and is probably semi jammed on the remains of the pin that is still lodged in the hole thru the shaft. Like Vic I very much doubt it's on a taper. WhaT I would do now is to draw the gear off the shaft with a puller or find a way to support it on both sides and drive the shaft out of it. Then you can clean out the remains of the pin and find a replacement. I expect the gear is an interference fit on the shaft so it should come with moderate persuasion but desist if it really is stuck. Twisting it off could risk damaging the prop's shear pin or the prop itself, but again, might be worth a try.

It may be that when the pin sheared the lateral forces on the crown wheel pushed it up the shaft a little and lost the mesh - that's my guess. Once the wheel is relocated with a new pin it should all mesh up again. Unless some cowboy has assembled this up from bits before selling it to you I don't see how a washer/spacer could be missing with this sort of construction so fingers crossed that aspect isn't an issue!

How you'll find a replacement pin I don't know but these things must be standard sizes, I'd go begging with the bits in hand around a repair shop or two. It will be very satisfying to get this running again, won't it?

If a pin was hard to find I'd consider welding the crownwheel on as its an old engine. It'll never come apart again but so what?

Was the pin solid or was it a hollow split cylinder of spring-steel (a roll pin) - look it up on wikipedia. It's not a shear pin, this one is not designed to break under load. The shear pin is behind the prop and is there to protect this one and the other gear-locating/fixing pins from damage. Don't replace this with a shear pin! It is either a roll pin (slotted spring pin) or a solid hard steel pin.

edit. Might be possible to grip the crown wheel lightly in the vise between soft jaws or two scraps of plywood or leather so as to tap the shaft through with that plastic hammer - by far the easiest way if it will come.

The gear has to come off in order to extract the remains of the pin. The shape pretty much rules out an ordinary three legged gear puller, I think. Mine would not grip it. A press would be ideal. Maybe a small engineering workshop would do it without charging the earth..
As it moves sufficiently to lose the mesh its not stuck fast. its only likely to be the remains of the pin holding it I would think.

Never had to buy a pin but they do come in standard sizes .. probably in large numbers though so the difficulty might be in buying just one.

Id doubt if its a solid pin. If it is the ends will have to be peened over to stop it coming out again.

Likely as MASH says a split spring pin, ( roll pin),

Or maybe a coiled spring pin

On reflection not likely!

I'm pretty sure it is a roll pin. I've managed to pull the gear up the shaft sufficiently by gripping the gear and hammering the end of the shaft - seems to have worked a treat. This is what is now showing:



It seems pretty firmly embedded, but has going to try and hammer it out, and if that fails then drill it.

When the new pin is in, what stops it from falling out?

 

[Pshaw]

Success! I've got the pin out, and now just need to source a new one. I'm not sure about what type of pin it is though, as from different ends it looks like each of the different types posted above!

https://fbcdn-sphotos-h-a.akamaihd...._=1377662415_3902fd495a247de7e1bc757137e94fdf

https://fbcdn-sphotos-h-a.akamaihd...._=1377669831_4f30172f54e386f190be9defc24fe320

https://fbcdn-sphotos-h-a.akamaihd...._=1377660261_242601336b41ed93d0d7b250ae37caf1

Do I have to get the specific part, or would a piece of metal dowel cut to the right dimensions work (the crown gear is so well attached to the shaft anyway that I had to really thwack it to get it to the position it is in now)?

Thanks,
Peter

 

[MASH]

I don't think dowel will do, I expect the pin needs to be hardened steel. I suggest you now throw yourself on the mercy of an outboard repair shop and see what they can dig out of their parts bins for you. If you can find a sympathetic mechanic you'll be home and dry I think. Well done, with luck you'll have a working engine again in a day or two.

 

[Pshaw]

MASH

VicS

I have a Machine Mart near me, so will pop down and try and see if any of these parts fit: http://www.machinemart.co.uk/shop/product/details/cht397-120-piece-roll-pin-assortment

If not it's only a matter of time until I can find the right part.

Thank you both very much for your help - if either of you are down Southampton way at any point let me know, I owe you a pint or two!!!

 

[VicS]

I have a Machine Mart near me, so will pop down and try and see if any of these parts fit: http://www.machinemart.co.uk/shop/product/details/cht397-120-piece-roll-pin-assortment

If not it's only a matter of time until I can find the right part.

Thank you both very much for your help - if either of you are down Southampton way at any point let me know, I owe you a pint or two!!!

Almost certainly be metric!
Can you measure the diameter of the holes .... using a set of drill bits

Worth trying any small engineering workshops.

Its going to have to be a good tight fit. You'll need to rig up some way of pushing it in using the vice

 

[Pshaw]

Yep, have already measured - it's an M4 hole. I was planning on gently easing it in using the rubber mallet again.

 

[VicS]

Yep, have already measured - it's an M4 hole. I was planning on gently easing it in using the rubber mallet again.

Id think if you can "ease it in" with a rubber mallet its too loose. There are special punches for driving roll pins.

 

[Pshaw]

Ah ok - I'll have a scout about to see what I can find - cheers!

 

[Pshaw]

Thought I'd update for anyone interested - tried to replace it with an M4 bolt, but sheared when above about 33% throttle. Replaced with another M4 bolt which ran for about 2 and a half hours at minimum throttle, about 3mph. Obviously not a long term solution, but a decent temporary bodge if you have to use it before a new part can be sourced!

 

[MASH]

I think this reinforces the idea that it needs to be a proper hardened pin. I can't see why you shouldn't get welded together if sourcing a pin isn't successful. If there's any looseness in any of the holes by enlargement due to the old pin working and shearing - which is highly likely - that may be the only way. One of the pics made the hole in the gear look oval - is it?

 

[White Rose]

Archimedes and Volvo Penta outboard spares

Yep, turn it over on the pull-cord and see if you can restrain the prop. If you can it proves the internal slippage hypothesis, if it can't be restrained and the mechanical drive between start cord and prop is solid I'd be very surprised.

I've never had one of those things apart but you might be pleasantly surprised if you can get that last screw out (impact driver?) and find the problem may well be amenable to a cunning repair. If a gear wheel is attached to a shaft and comes undone it can probably be refixed somehow. It may be no more than a loose nut and sheared woodruffe key. I think the movement of the shaft under the hammer suggests that whatever normally restrains it in runout has come loose. Betcha it's the same thing that's disconnected the drive - likely the gear on the far side of the bearing.

I presume the engine is an old one and you're reluctant to spend out on a commercial repair?
Where are you ?

Hi,

Have you sorted the problem yet? I may be able to help when you need replacement parts, new or used but in good order. I have recently taken over the remaining stock of Archimedes and Volvo Penta outboard parts from the former main dealer in The Netherlands. 2000+ partnumbers and all workshop manuals, spare part lists and user manuals. Let me know if I can be of assistance. Part of a hobby that got somewhat out of hand.
Rgds,
JW

 

[rotrax]

Thought I'd update for anyone interested - tried to replace it with an M4 bolt, but sheared when above about 33% throttle. Replaced with another M4 bolt which ran for about 2 and a half hours at minimum throttle, about 3mph. Obviously not a long term solution, but a decent temporary bodge if you have to use it before a new part can be sourced!

For what it is worth, many years ago at a Speedway meeting in the far flung reaches of the old communist Czechoslovakia a friend had a similar situation with a Magneto drive. It too required a 4mm High Tensile pin-a hardened pin may be too brittle.

A small and very expensive Snap-On phillips screwdriver supplied the 4mm top quality steel for making a pin, which was still in use last year.

Your answer may be in the toolbox................................