Many thanks NApoleone,
your nick I remember to have heard it sometime...
but I had visited this website last week, however many thanks for your help.
See you on this forum for an another topic.
Eng. Antonino Nicosia
Aeronautical Engineer specialized in Fluid Power field.
my website: web.tiscali.it/aeronavigandosulweb
(in the future there will be many programs about fluid power problems, thermal and structural problems)