Courtesy of Hans van Dissel
Herkules is an Austrian make, founded in Vienna by Egon Friedrich Polzer in 1948. The firm specialized in high quality 0 gauge. The loco Tony showed is the Arlberg type; I don't know if Herkules produced other locos - this one always seems to be the one that turns up on eBay - if and when any Herkules loco turns up. Herkules also produced some imposing 40 cm bogie coaches, fitted with interior lighting. The firm also produced some lineside accessories and closed in 1952. I don't know if Herkules ever produced a catalogue; I've never seen or heard of one.