MULTI-PRESSURE CONTROL SYSTEM

摘要

A multi-pressure control system for a backup type welding gun and similar apparatuses including a positioning directional control valve for controlling the extension and retraction of the positioning or backup cylinder. A multipressure air sequence circuit and a time delay means operatively connected to the air sequence circuit for controlling the admission of a predetermined low pressure into the retract port of a backup type welding gun positioning cylinder to speed up the extension movement of the position piston carrying a weld cylinder, and thence to control the admission of a predetermined higher retraction pressure higher retraction into said retract port, after a predetermined time delay interval. A welding pressure fourway directional control valve operatively connects a multipressure selector air circuit to the weld cylinder operating port to provide a plurality of pre-set pressures to the weld cylinder operating port for carrying out welding operations at selective pressures and in selected sequences.