Selective air pressure control system for welding and like apparatus

An air pressure control system for supplying various selective, sequential pre-set air pressures from a source of pressurized air to an air cylinder or the like, for operating welding and similar apparatus, characterized in that it includes:

• (a) a pilot air operated pressure regulator valve having a pilot air operator and a working air flow control valve operatively connected in series in a pressurized working air conduit means between said source of pressurized air and said air cylinder;
• (b) a pilot air pressure selector circuit means connected between said source of pressurized air and the pilot air operator of said pilot air operated pressure regulator valve, for selectively and sequentially providing a plurality of small pre-set pilot air pressures to the pilot air operator of said pressure regulator valve, for operating the pressure regulator valve to selectively and sequentially supply a plurality of larger pre-set working pressures to said flow control valve and thence to said air cylinder for operating said air cylinder in a sequence of various pressure operations;
• (c) said pilot air pressure selector circuit means including a plurality of pressurized pilot air conduit means which are connected in parallel with each other, with one end of each pressurized pilot air conduit means being operatively connected to said source of pressurized air and the other end thereof being operatively connected to the pilot air operator of said pilot air operated pressure regulator valve;
• (d) a first one of said plurality of pressurized pilot air conduit means has operatively connected therein a pre-set output pressure regulator valve;
• and,
• (e) each of the others of said pressurized pilot air conduits has operatively connected therein a pre-set output pressure regulator valve connected in series with a solenoid operated directional flow control valve.