Girostarter help needed.

[Barry]

That is fantastic news Nick.

I was thinking along the lines of a sprag clutch as a replacement for the 'crunching' gears?

http://en.wikipedia.org/wiki/Sprag_clutch

https://www.google.co.uk/search?q=sprag+bearing&source=lnms&sa=X&ei=8rg8UoT1L63Y0QXox4GgDw&ved=0CAYQ_AUoAA&biw=1536&bih=844&dpr=1#q=sprag+bearing&tbm=shop

https://www.google.co.uk/search?q=sprag+clutch&tbm=isch&tbo=u&source=univ&sa=X&ei=kLg8UoG6L4eQhQfR7YHoCg&sqi=2&ved=0CDwQsAQ&biw=1536&bih=844&dpr=1

https://www.google.co.uk/search?q=sprag+clutch&tbm=isch&tbo=u&source=univ&sa=X&ei=kLg8UoG6L4eQhQfR7YHoCg&sqi=2&ved=0CDwQsAQ&biw=1536&bih=844&dpr=1#q=sprag+bearing&tbm=isch

Not sure quite how to incorporate it but it looks like it's along the right lines?

[Bob Purton]

That's good news Nick. Sounds like the French Inter good old boys network is functioning well. I got a lot of help from those guys when doing mine.

Barry, not sure you were on the right track. All the parts do is joint two sections of a shaft together by a long bolt through the centre,  there is no unidirectional element or clutch, the clutch is inside the gyrostarter unit. Once this is bolted up that's it, it doesn't move like  a ratchet its fixed in position permanently. .

[NickPoll]

Until the bolt comes loose !!!!
                        Nick.

[Barry]

That's good news Nick. Sounds like the French Inter good old boys network is functioning well. I got a lot of help from those guys when doing mine.

Barry, not sure you were on the right track. All the parts do is joint two sections of a shaft together by a long bolt through the centre,  there is no unidirectional element or clutch, the clutch is inside the gyrostarter unit. Once this is bolted up that's it, it doesn't move like  a ratchet its fixed in position permanently. .

I understand now Bob.  Thanks. That makes it much easier to fix (not easy though) because you can do anything you like with the worn ends as long as the end result is concentric, the right size and doesn't fall apart.

[Bob Purton]

You could but I think this arrangement was used because it spreads the stress the most evenly across the joining surfaces. Remember the start up process involved a very sudden power kick in, not a gentle start up like a dynastart. For instance if a woodruff key was used it would shear in no time at all.

[NickPoll]

I know, I'll weld the crank to the Girostarter. That'll keep the bugger in place.                             Nick.

[Barry]

You could but I think this arrangement was used because it spreads the stress the most evenly across the joining surfaces. Remember the start up process involved a very sudden power kick in, not a gentle start up like a dynastart. For instance if a woodruff key was used it would shear in no time at all.

I can see what you mean. There was method in their madness.
Is there a decompressor?

[Rusty Chrome (Malcolm Parker)]

You could but I think this arrangement was used because it spreads the stress the most evenly across the joining surfaces. Remember the start up process involved a very sudden power kick in, not a gentle start up like a dynastart. For instance if a woodruff key was used it would shear in no time at all.

That answers the question I was thinking of asking! Never heard of this type of connection before or what it was for, but I knew I'd seen it somewhere else when I saw the photos. Fascinating stuff!

[Bob Purton]

Thought it worth mentioning that the outer end of the gyrostarter is also supported by a bearing in the outer casing so this toothed joint isn't supporting the whole thing on its own.  They are an amazing device and must have cost a fortune to develop and produce, too complex to be reliable though. You can see how the simplicity of the Dynastart won the day, no contest.