The May 2018 issue of Model Railroader magazine features an article I wrote on how to Build a Working Overhead Door. The article describes the detailed steps I took to build the operating overhead door you see in the above photo. In addition, check out the How to model an operating overhead door video in the How To section of my website that shows the overhead door in operation and the "behind the scenes" action of the gear mechanism.
This simple project adds a lot of interest to an operating session as crews have to take the time to open the door and follow prototype procedures before switching the industry. These actions replicate what the crews on the prototype Georgia Northeastern Railroad encounter every day at the Georgia Metal Coaters facility when they switch the industry. The modeled Georgia Metal Coaters facility accommodates two coil cars inside the structure. My operating crews must stop prior to shoving cars inside the structure to uncouple and then off set the couplers between the cars, before finally spotting the cars inside the facility, because once the coil cars are inside you can't access the couplers for manual uncoupling. Crews are also required to open the door prior to coupling to any cars located outside the facility door to prevent accidentally shoving a car into the closed door and damaging it, the same procedure is required on the prototype.
The Lego gear reducer is a very versatile mechanism as it can be used in numerous ways to make various features operate. On my layout I used the same mechanism to make the facility fence gates operate as well as the overhead door. Many modelers have asked if it is possible to connect it to a motor instead of manually operating the gear reducer and the short answer is, yes. It would take a bit of work to connect the motor to the operating shaft of the gear reducer but it is possible. You would also need to provide limit switches to shut off the motor once it reaches the full up or down position. For me, I prefer the simple manual method and it works perfectly every time.
If you want to build an operating door on your layout, be sure that the building you select has enough room above the door opening to accommodate the door in the full open position, plus a little more. This extra room allows room for the gear reducer mechanism to be placed above the doorway and engage the back of the door without blocking the opening. Each installation will be a little bit different but with a little engineering and imagination most issues can be overcome. I hope my overhead door project inspires you to build your own operating door.