an automated bag filling machine particularly adapted to handle reclosable fastener strip profile - type plastic bags fed into the machine in a bag chain employs stations for opening , filling , reclosing , and separating filled and closed bags from the remainder of the chain . the drive means for conveying the chain through the filling mechanism include stroke control devices which enable the operation of the machine to be changed over for handling bags of different width sizes . means are also provided for automatically preventing the bags in the chain from excessively over traveling their proper registration points with the various work stations .