[Richard Farrant]

Originally Posted by Tony Wheeler

and while the locking mechanism isn't quite clear to me there's obviously a retaining cage of some kind, possibly sprung, to keep it in both the locked and retracted positions.

Hi Tony,

It may have an arrangement at the folding joint, not unlike that on the crank handle support legs of semi-trailers. One part of the shaft could have a male extension that enters in to a hole in the other part and hinge joint could be slotted to allow the shafts to lock together.

Richard