Pull Systems

This is the Lean concept that value should be “pulled” from downstream in the value stream by a consumer, backward up the value stream. “Pull” is initiated by a consumer, when the work or item he/she wants or needs it and then proceeds backwards up the value stream. It is the opposite of a “push” system where providers produce a product or service (or information) and then “push” it onto the consumer, down the value stream regardless of whether the consumer wants it or needs it (at that time or at all). This results in much waste, work-in-progress inventory, possibly unnecessary production, increased warehousing and lost capital. All are forms of waste (muda). An example of a “pull” system is filling the gas tank in your car. You don’t typically just put gas in your car at arbitrary times or times scheduled far in advance, regardless of fuel usage. You wait until the gas gauge reads relatively near empty. The gas gauge is the initiating trigger (visual sign). It “pulls” the need to put gas into the car at just the right time, and in just the right amount. The doctor “pulls” the taking of radiographs as needed. Radiographs are not simply taken because a patient has presented to the practice. Supplies are generally ordered on a pull system in a Lean organization, both the restocking from a supplier or distributor to the location, and from a stock room to each point of use, like exam rooms.