Also known as a carriage, the garage door trolley is the rail between the motor and the garage door. It connects the door to the mechanism of the opener usually through a bar or chain that stretches across the ceiling of your garage. The operating arm, connected to the trolley, provides the push or pull to raise or lower your garage door. Usually, its installed at the same time as the opener but may wear out before the opener, in which case it will need replacing.
Here’s how to replace the carriage assembly of your garage door.
Disconnecting the Door & Carriage
First, disconnect the motor from the electric outlet to avoid shock. If the opener is wired to an electric box, turn off the breaker.
Pull the release cord of the trolley to disconnect it from the door. This is the cord hanging from the assembly. Next, raise and lower the door by hand so that the carriage assembly is pulled to the outer end of the rail.
Place a ladder near the end of the rail at the wall above the door opening. Remove the cotter pin from the cotter bolt that attaches the upper end of the door arm to the carriage with a pair of pliers.
Replacing the Carriage
Remove the bolt that connects the rail to the wall bracket. Fit the replacement carriage onto the end of the rail and reconnect the rail.
Run the garage door. This should automatically reconnect the door to the opening assembly.