Garage Door Opener Common Parts Glossary

2-strand copper wire

2-strand copper wire is used to connect the logic board of the garage door opener to the safety sensors and to the wall control.

AC motor

The AC motor rotates the sprocket, which drives the chain to move the trolley along the rail to raise and lower the garage door. Replace the motor if it doesn't run when activated.

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Battery

Some garage door openers have a 12-volt back-up battery inside the motor unit. During a power outage, the back-up battery supplies power to the motor unit so the door can open and close.

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Belt

The belt attaches to the trolley track and rotates around the garage door opener rail. One end attaches to the motor pulley and the other end rides on the idler pulley the front of the rail assembly. The belt moves the trolley to raise and lower the garage door.

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Bracket

The garage door opener bracket is the lifting point for the garage door. It's attached to the inside of the garage door and connects to the curved arm. The curved arm links the garage door bracket to the trolley. The movement of the trolley on the rail assembly raises and lowers the door.

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Chain and cable

The chain and cable of a garage door opener are mounted on the trolley track. One end attaches to the sprocket on the motor unit. The other end is routed through the cable pulley at the front of the rail assembly.

DC motor

The DC motor rotates the motor pulley, which drives the belt to move the trolley along the rail to raise and lower the garage door. Garage door openers can use a back-up battery to run a DC motor during a power outage.

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Drive and worm gear kit

The drive and worm gears spin the sprocket, which drives the chain to move the trolley along the rail to raise and lower the garage door. By design, these plastic gears break to protect the motor from damage if the garage door suddenly jams up on a bent track and quits moving when the opener raises or lowers the door. The kit contains both gears and the related parts needed to install the gears.

Emergency release

The emergency release for a garage door opener consists of a rope with a handle that's attached to the release catch on the bottom of the trolley. Pulling the handle disconnects the garage door from the trolley so that the door can be manually opened and closed during a power outage or if the garage door malfunctions.

Gear and sprocket assembly

In a garage door opener, the sprocket is the component that drives the chain which moves the garage door up and down. The base of the sprocket attaches to the end of the shaft that extends from the top of the motor unit. The drive system rotates the gear to spin the sprocket and move the door.

Idler pulley

The idler pulley of a garage door opener attaches to the front of the rail assembly. It supports the chain cable or belt and allows for the smooth movement of the chain or belt drive system.

Light socket

The light socket for a garage door opener is the threaded receptacle for the light bulb that's located on the side of the motor unit.

Logic board

The logic board of a garage door opener is the main control board that controls the functions of the opener. It detects signals from the remotes and the sensors, and it sends voltage to the drive motor to open and close the garage door.

Motor unit

The motor unit of a garage door opener is the assembly mounted at the back of the rail assembly that contains the motor, logic board, switches and lights.

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RPM sensor

The RPM sensor monitors the speed of the motor and sends the speed signals to the logic board. When the RPM sensor is defective, the door only moves 6 to 8 inches at a time and the LED light flashes 5 times.

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Radio frequency tester

Technicians use a radio frequency tester to find RF interference when your remote only works when it's close to the motor unit. The radio frequency tester identifies signals from household items such as security lights or motion sensors that interfere with garage door opener remote device signals.

Rail assembly

The rail assembly for a garage door opener is the support rail that runs from the motor unit to the front wall of the garage just above the garage door. It houses the trolley, chain and cable assembly, and cable pulley.

Remote

The remote for a garage door opener is a radio frequency (RF) transmitter that's typically clipped to the visor in your vehicle. It sends a signal to the motor unit to open or close the garage door.

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Safety sensor

The safety sensors are a pair of photoelectric eyes mounted at the bottom of the garage door travel rails. One sends a beam of infrared light and the other receives it. If the receiving sensor doesn't detect the beam—either because the sensors are misaligned or because an abject is between them— the safety sensors signal the logic board to reverse the direction of the closing door.

Safety sensor kit

The safety sensor kit for a garage door opener contains the photoelectric sending and receiving eyes, as well as the mounting hardware, wiring and wiring connectors. The photoelectric eyes are mounted on the bottom of the garage door travel rails. If an object, person or animal blocks the beam between the sending and receiving eye, the closing garage door returns to the fully open position, and the lights on the opener blink.

Travel limit switch

The garage door opener's travel limit switch is a sensor that detects the position of the garage door so the motor doesn't keep running when the door is fully open or fully closed. The travel limit switch is mounted behind the control panel. To set the up and down movement of the garage door, adjust screws on the switch that extend through the face of the control panel. One screw sets the up travel limit and the other sets the down travel limit.

Trolley

The trolley of a garage door opener is a travelling bracket mounted on the rail assembly and attached to the top of the garage door by a linkage system. The chain and cable system moves the trolley on the rail assembly to open or close the garage door.

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Wall control

The wall control unit for a garage door opener is mounted on the wall of the garage beside the entry into the house. Wires connect it to the logic board on the motor unit. The wall control unit controls the motion of the door, as well as lighting and programming.

Wireless keypad

The wireless keypad for a garage door opener is a battery-operated remote keypad typically mounted on the garage, next to the garage door. It communicates with the garage door opener motor unit through radio frequency (RF) signals. Entering a code on the keypad opens the garage door.