I believe the term "Axel" is losing it's intent from your country to ours!
The pic you show seems to be one of the aforementioned "outrigger" attachments available for the Wing and other bikes. Brands already posted.
There is not a straight axle available, as far as I know that can be added and maintain the original saddle bag position.
If I were to be interested in one of these "outrigger" models, I would give some very serious consideration to the
http://www.triggtrikekits.com/trike-models/honda
Called a trike conversion, it and others like it are not true trikes as they maintain the original configuration of the bike and add 2 extra wheels to the bike.
Another item to consider when adding one of these is the "steering" of the bike. I found it most difficult to steer. A rake kit on the front suspension would be needed for me but, this then prevents the unit from being removed to ride as a 2 wheel bike again.