The short answer to that question is kind of: it doesn’t. The actual automatic opener unit for overhead doors doesn’t do a whole lot of the lifting and lowering work – all the other parts do. The opener unit basically manages the entire process; it receives the signal to open or close, and prompts all the other parts to work together to lift and lower the door. It’s a replacement for people. If you’ve ever manually lifted an overhead door, you know that the effort it takes is not nearly equal to the weight of the door.

Here’s how:

  • The overhead garage door itself has brackets and hinges that coordinate with rollers which are guided in a track.
  • There is a cable (or belt) also running the vertical length of the track up to the header bar, where it sits in a pulley.
  • At the middle of the header bar, a trolley track runs perpendicular back to the motor unit. This is connected with an arm attached to the top of the overhead door.
  • On either side of where the trolley track is attached to the header bar are torsion springs. These do the majority of the work in lifting and lowering the overhead door.
  • As the door moves, the cables turn the pulley, which releases (opening) or increases (closing) the torque on the tension springs.
  • When the vertical lift is complete, the arm is guided by the trolley carriage back toward the automatic opener unit, sliding the garage door horizontally until it’s all parallel with the ceiling.

It seems complicated, but it’s really just a whole system working together. Kind of like those marble obstacle course videos where everything has to coordinate exactly for the marble to make it to the end of the course.

Check out this fun YouTube episode of “Physics at Home” for a visual take on how a typical overhead garage door opener system works.