21 replies to this topic

[GraemeC]

But then he'd have to put the engine back on the box     

[pete l]

What would break that though ?

[Ethel]

Dunno why I liked your mainshaft been shot, but that new photo does look a lot like it. Certainly smaller & thicker than my guesses, the inside radius should show it it's broken off a larger part.

 

What would break that though ?

 

Could take less than you think. If it trapped a bit of debris that scored the base of the flange to create a stress riser, then got wedged while another gear was driving the shaft at a different speed....

[mini13]

Doh! 

 

But then he'd have to put the engine back on the box     

 

 

might just be unlucky ie a problem part from the factory,

[Spider]

Dunno why I liked your mainshaft been shot, but that new photo does look a lot like it. Certainly smaller & thicker than my guesses, the inside radius should show it it's broken off a larger part.

 

What would break that though ?

 

Could take less than you think. If it trapped a bit of debris that scored the base of the flange to create a stress riser, then got wedged while another gear was driving the shaft at a different speed....

 

It's the first one I've seen broken, though I have often looked at it and almost marveled that they don't break. It's a fairly hard part of the shaft and being relatively thin, it's likely through hardened or close too, which also makes it a bit brittle.

 

Could have been as Ethal has suggested, or badly mishandled at some point and dropped on the ground at just the right angle or some ham fisted git had banged it with a hammer or maybe even as Mini13 suggests, a duff part, or if 2nd or 3rd gear had too much axial clearance, that would cause that gear to lay over when loaded and so spot loading that part of the shaft.

 

Suffice to say, that it's a rare problem and replacing the shaft would likely be all it needs, along with checking of the bearings and clearances between 2nd and 3rd gears to the shaft and all else in there while it in bits.

[Ethel]

I imagine you could generate some pretty fantastic forces. Gate change down from 4th to 2nd and you could instantly add a 3000 rpm differential - could turn a 2nd gear synchromesh in to a pretty nifty jack hammer 

[richw911]

Many thanks indeed for all of the help and input