Are you trying to figure out what’s wrong with your garage door?
Reading a garage door diagram can help.
When you troubleshoot your garage door problems, and find a faulty piece, you need to know what that piece is called so you can a) go purchase a piece and replace it yourself, or b) call and tell the garage door repairman what’s wrong with your door.
Either way, you need to know what’s wrong with your garage door.
And knowing how garage doors are put together and how they work is critical to understanding how to fix them.
In this article, we are going to explain the three main aspects of a garage door:
- The frame
- The moving parts
- The electric garage door operator

Frame
The garage door “frame” is the name we’re giving to the parts of your garage door system that are fixed in place and guide the moving parts.
This “frame” includes the horizontal door tracks, the horizontal door tracks, the horizontal trolley track, the vertical door tracks, the hanger kit, the flag bracket, the jamb brackets, and the bottom rails.
These parts are highlighted in the image above.
These are the parts which are stationary, and direct where the door moves.
Let’s examine each part:
Tracks
Flag Brackets & Jamb Brackets
Hanger Kit
The hanger kit is made up of pieces of galvanized steel with pre-punched holes in it, which can be used to attached the electric garage door operator to the ceiling and the tracks to the ceiling and the wall. They come unassembled so that you can adjust the height needed for each area they are used.
Bottom Rail
The bottom rail is the lower-most horizontal rail of a door section. On the bottom of a garage door, this piece is frequently a problem if the floor is uneven or it the rail itself is broken or warped. This can allow water and debris to enter your garage, as well as energy loss.

Moving Parts
The moving parts are those parts which are used to move the garage door up and down.
These parts include the rollers, the hinges, the pulley and cable, the belt, the curved door arm, the torsion spring, the emergency release rope, and the cable drums.
You can see these parts in the above image.
Here, we’ll explain each part individually:
Rollers
Hinges
Pulley & Cable
The cable is what is attached to both the springs and the electric garage door operator. This lifts the door. The pulley is used because garage doors are very heavy, and can be upwards of 250 lbs. A pulley lessens the amount of force needed to pull the garage door upwards and let the garage door back down gently.
Curved Door Arm
Emergency Release Cord
Torsion Spring
Cable Drums
Chain / Belt / Screw
A garage door chain uses a chain (much like a bicycle chain) to move the door up and down. The cheapest of the three options, the chain will last a long time under normal circumstances. A chain will occasionally need adjustment, which is a simple process most people can do themselves.
A garage door belt works the same as a garage door chain, except it has a steel-reinforced rubber or polyurethane belt instead of a chain. While effective primarily for lighter doors (chains work better for heavy doors), garage door belts are the quietest option.
A garage door screw uses a threaded steel rod to rotate the electric garage door motor and wind the garage door up. While the most expensive option, a garage door screw does not need to be adjusted.

Electric Garage Door Operator
The garage door operator is the motor, attached to your ceiling, which opens and closes your garage door. Surprisingly, these were invented way back in 1926!
The operator itself does not provide most of the power which opens the garage door – the springs and the pulley system make up much of the torque required. The motor powers the trolley, which uses the chain, belt, or screw to raise and lower the door.
If you can’t find any hardware problems with your door, then frequently it is an electric garage door operator issue. Call a professional to come out and repair it.
Conclusion
We hope this helps give you an idea of how garage doors work, and which parts do what:
- Frame
- Moving Parts
- Electric Garage Door Operator
Having this information can help you troubleshoot on your own.
Whether you are going to fix the door yourself, or call a professional, don’t hesitate to contact us at G&S Garage Doors with any questions you may have. We would love to answer your questions.
Many thanks to GarageDoorNation and the DIY Network for their beautiful garage door graphics!