Vetus Type 6 Coupler Slipping on Shaft

[anothertaylor]

I have about 0.2mm of wear on my shaft where the clamping failed on a Vetus Type 6 coupler. In forward it is slipping, in reverse it is not. I am thinking this is shaft related not coupler.

I need to avoid the expense of haul out and shaft replacement. Does anyone know any options to shim the shaft, or anything else I can do to avoid a haul out and shaft replacement? Pictures attached.

[stormalong]

When I installed one the shaft was keyed. I had a machine shop cut a keyslot on the type 6 to match. A proper broach made this an easy job. With a 1-1/4 inch shaft and there was plenty of metal on the type 6 to cut the slot. Unfortunately if your shaft is not cut for a key you would need to remove it for machining. I also drilled a dimple in the shaft and put a setscrew in it to prevent the shaft from pulling out in reverse.

IIRC the original (IMO very poor) instructions illustrated drilling a hole through the shaft for a pin. Drilling a stainless (Aquamet 22) shaft is not easy and unless you are a pro I would take it to a machine shop to get it done so same problem. A pin solves both problems - slipping and pullout. I didn't like the idea because of the torque being applied to the pin and the forces involved in both the shaft weakened by a hole and a pin of questionable strength. I am not an engineer and sizing such a pin would require some proper engineering.

[SailingHarmonie]

This coupling is not designed to work by clamping force alone. The clamping feature is there to ensure the coupling is accurately centered on the shaft with no runout. It can not transmit drive torque. It needs the pin, or be modified to use a key. That is not optional.

The issue is not the shaft, or the coupling. It is the installation.

[anothertaylor]

Originally Posted by SailingHarmonie

This coupling is not designed to work by clamping force alone. The clamping feature is there to ensure the coupling is accurately centered on the shaft with no runout. It can not transmit drive torque. It needs the pin, or be modified to use a key. That is not optional.

The issue is not the shaft, or the coupling. It is the installation.

This is from another thread which is directly from an email from Vetus

[I][I]"These pins are only designed as a safety measure to prevent the shaft from pulling out of the coupling when in reverse if the clamping system fails , as there are broken I would suggest the clamping force onto the shaft has come loose enabling the drive to be taken through the pins"

So I don't think it is the pin, and that they do indeed work by clamping. The diagram also has a key but my coupling and shaft do not. I am going to try and shim.

Has anyone had any success shimming the shaft inside the coupling?

[skipperpete]

Originally Posted by anothertaylor

This is from another thread which is directly from an email from Vetus

[I][I]"These pins are only designed as a safety measure to prevent the shaft from pulling out of the coupling when in reverse if the clamping system fails , as there are broken I would suggest the clamping force onto the shaft has come loose enabling the drive to be taken through the pins"

So I don't think it is the pin, and that they do indeed work by clamping. The diagram also has a key but my coupling and shaft do not. I am going to try and shim.

Has anyone had any success shimming the shaft inside the coupling?

The advice from Vetus is 100% correct…. no key or pin is required, once installed correctly that style of shaft locking device is damn near impossible to remove and I’ve struggled with these on a number of occasions to do a simple job like changing the bellows on a dripless shaft seal. If the shaft is worn it might be possible to cut off the worn bit and reinstall the locking hub on unworn shaft but this fix assumes that the coupling collet I.D is relatively unworn and if it’s even possible to cut 2” off the shaft and not have the prop getting too close to the bearing. Get the correct tool to tighten the castellated nut on the Vetus coupling, the solution could be as simple as tightening the nut, not easy to do without solidly locking the prop shaft to apply enough torque to securely apply the pressure. I wouldn’t use shim stock to try and fix this but if you do, maybe use the dreaded loctite and pray you never have to remove the Vetus again ( unless you have oxy acetylene aboard) that particular coupling can tolerate a lot of mis alignment so that’s to your advantage as well.
For those who are skeptical about keyless couplings and propellers, they’ve been an industry standard for at least 40 years, heavy duty ZF gearboxes have shrink fit input couplings and the largest ships have keyless propellers and a nifty gadget called a “Pilgrim Nut” to remove and install em.

[NorthCoastJoe]

I have used JB weld to hold a main oil galley plug that blew out once. It might be enough to get you by until you can do it right.

Just be super crazy about getting it all clean "physically and chemical" clean, and let it cure the proper time before testing it.

[stormalong]

Originally Posted by NorthCoastJoe

I have used JB weld to hold a main oil galley plug that blew out once. It might be enough to get you by until you can do it right.

Just be super crazy about getting it all clean "physically and chemical" clean, and let it cure the proper time before testing it.

And then what? Are you going to heat it with a blowtorch to get it off?

[Paradox111]

https://www.cruisersforum.com/forums...ns-179781.html