Addendum ;
The last para of the translated patent; "With the goal of reducing to the minimum all projections or recesses, even the opening of the pedal hub on the end of the crank, is closed by a small pressed lid threaded on the outside and with a polygonal central hole for the introduction of a tool for screwing and unscrewing."
refers to the crank dust cap - not some previously unseen cover at the pedal end of the crank !
Bob Reid Stonehaven Scotland
http://www.flying-scot.co.uk (mapped)