http://drivenrollers.tripod.com/
http://rollerconveyor.pbworks.com/
https://rollerconveyors.shutterfly.com/
http://conveyor-roller.deviantart.com/
http://conveyorroller.hatenablog.com/

Conveyor system applications are so invaluable to modern industries. The concept of gravity roller conveyors has been available since the beginnings of documented history. It's believed that the roller method was used in the construction of the old Egyptian pyramids and Stonehenge, among many other things.