Shaft coupling oddity - anyone recognise it?

[starman]

Has anyone come across a driveshaft coupling like this one? It’s on our ‘80s Les Allen with DM2 & PRM150. 
 

it smacks to me of being a one-off - possibly put together out of a few bits around the yard. 
 

Reason for asking is that there’s play where circled between the tailshaft and centre shaft. Everything will have to come apart to investigate and maybe the coupling should go at this stage too. 

[David Mack]

I suspect that there was originally a metalastic coupling (rubber) between the two flanges, and that has subsequently been replaced with what looks like sheet metal. As a result the upper flange in the picture does not engage properly with the shaft. It all needs dismantling and looking at by someone who knows what's what. But you may have trouble sourcing a new metalastik coupling element - there is another current  thread running on that subject.

 

[Tony Brooks]

I think that I have tries to advise Starman on this a few months ago. I do not recognize that particular coupling, but I suspect the boss that is loose on the shaft is keyed so the key drives the shaft. The boss is then prevented from moving by the grub screws. It may even have been shrunk onto the shaft. I think that for whatever reason, and what David said is one very good one, the boss has been fretting on the shaft so the key and keyway are probably worn. As it has come loose so soon after tightening the grub screws I am sure it needs to come apart for measurement and inspection.

[starman]

37 minutes ago, Tony Brooks said:

I think that I have tries to advise Starman on this a few months ago. I do not recognize that particular coupling, but I suspect the boss that is loose on the shaft is keyed so the key drives the shaft. The boss is then prevented from moving by the grub screws. It may even have been shrunk onto the shaft. I think that for whatever reason, and what David said is one very good one, the boss has been fretting on the shaft so the key and keyway are probably worn. As it has come loose so soon after tightening the grub screws I am sure it needs to come apart for measurement and inspection.

You did indeed Tony. It’s curiosity really about the coupling and whether (as i suspect) it’s a one-off or maybe a Les Allen speciality. 

 

57 minutes ago, David Mack said:

I suspect that there was originally a metalastic coupling (rubber) between the two flanges, and that has subsequently been replaced with what looks like sheet metal. As a result the upper flange in the picture does not engage properly with the shaft. It all needs dismantling and looking at by someone who knows what's what. But you may have trouble sourcing a new metalastik coupling element - there is another current  thread running on that subject.

 

It’s been replaced by what appear to be chunks of rubber or leather. 

[Rose Narrowboats]

It's a Fenner - possibly type HRC.

[David Mack]

31 minutes ago, starman said:

It’s been replaced by what appear to be chunks of rubber or leather. 

Whatever it is, it looks very insubstantial for the task. I can't find a picture of Fulbourne's metalastik insert, but here is the whole setup - the ribber insert must be a good inch thick.

[Rose Narrowboats]

https://shop.eriks.co.uk/en/mechanical-power-transmission-shaft-couplings-flexible-couplings/spider-for-hrc-jaw-coupling-pr-rc0023-0131-jb/

Just now, David Mack said:

Whatever it is, it looks very insubstantial for the task. I can't find a picture of Fulbourne's metalastik insert, but here is the whole setup - the ribber insert must be a good inch thick.

That does look homemade - out of a couple of R&D half couplings.

 

The rubber drive part is within the steel couplings on that particular Fenner, and is more substantial than it looks.