Straight-Line and Rotary Systems Packaging machines such as fillers, cappers, and labelers can be designed in straight-line and rotary configurations. Straight-line machines usually index a product into an operational station and then hold it there until the operation is completed. For example, intermittent-motion straight-line fillers move containers under the filling heads and then stop for the fill cycle. (Figure 18.1.) The machine may have one fill head or several fill heads ganged together.Straight-Line and Rotary Systems Packaging machines such as fillers, cappers, and labelers can be designed in straight-line and rotary configurations. Straight-line machines usually index a product into an operational station and then hold it there until the operation is completed. For example, intermittent-motion straight-line fillers move containers under the filling heads and then stop for the fill cycle. (Figure 18.1.) The machine may have one fill head or several fill heads ganged together