Piston filling machines
The piston is drawn back in its cylinder so that the product is sucked into the cylinder. A rotary valve then changes position so that the product is then pushed out of the nozzle instead of back into the hopper.
This type of piston filler is best suited for viscous products that are paste, semi paste, or chunky with large particlates. These piston fillers are built to meet food grade standards and can also handle various chemical applications.
Heavy sauces, salsas, salad dressings, cosmetic creams, heavy shampoo, gels, and conditioners, paste cleaners and waxes, adhesives, heavy oils and lubricants.
This lower cost conventional technology is easy to understand for most users. Fast fill rates are achievable with fairly thick products. Warning: this technology is nearly obsolete with the advent of servo positive displacement fillers.