Bruce again many thanks for your encouraging remarks i do realise that the key will be choosing the correct size gear problem is i don`t think anyone has done this before i.e. worm drive so for me it will be trial and error. Good news the small pressure gauge i ordered has arrived this morning so i will be able to tell pressures from my little compressor and boiler ( will need to make adaptor first ) and to top all that the Sun is shinning this morning surely i`ll get something done.
Best regards