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What is a Power and Free Conveyor System?

Dec 5, 2012 | Blog

Pacline carries Unibilt power and free conveyors

A Power and Free conveyor can be thought of as a train track system, with multiple trains moving independently, starting and stopping, changing tracks as required to get them where they need to go. We refer to this as a non-synchronous conveyor.

Power and free conveyors get their name from the basic design; the engine is a continuously moving “power” chain running in the upper track, and the loads are suspended from “free” trolleys located in the lower track. The “free” trolley has a cast body and 4 load carrying wheels. It has a front flipper, and a rear flipper. The cast pusher dog mentioned earlier rides between these two flippers, and controls the movement of the trolley forward but also restrains it if it is going down a decline. The powered chain has a cast iron “drive dog” attached that will engage with the flippers of the free trolley, thus propelling it forward.

Power and free conveyor for oven curing process.

The most common style of power and free conveyor is where the load is being carried beneath the track, (we call it “slot down”).

This particular conveyor can also carry the load above the track, making it ideal for the highest quality paint systems where zero defects can be tolerated. Anything originating from the conveyor, be it oil or dirt, is eliminated. This feature also allows it to be used for over/ under systems, which reduce the amount of space used.

In conclusion, the power and free conveyor can be a large investment compared to a simple overhead conveyor and so it is best applied to more expensive products being carried through complex processes that extend over multiple shifts. These factors will all contribute to a suitable ROI. 

Due to the complexity of Power and Free systems, Pacline would need to know some answers to the following questions to begin developing a solution:


  • What is the product being carried? Maximum weight and dimensions?
  • What is your throughput/rate of production? What is the quantity of parts required on the system?
  • Can you describe your process in more detail? i.e. do you have any robotics?
  • Do you require any special accumulation areas? If so, why? Do you require any switches on the system?
  • Do you have a layout showcasing the desired conveyor path through your facility?


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