The LiftMaster 41A2822-1 Interrupter Cup is a factory replacement timing wheel used on select LiftMaster, Chamberlain, and Craftsman garage door openers equipped with an optical RPM sensor. Mounted on the motor shaft, this cup spins through the sensor to provide tachometer feedback that controls motor speed and travel logic. A worn or broken cup commonly causes the motor to start and stop erratically, hum without lifting the door, or reverse unexpectedly, making this component a key diagnostic and repair part for restoring proper operation on compatible AC motor chain- or belt-drive openers that use an optical RPM board.
Installation typically involves disconnecting power, removing the opener cover, sliding the interrupter cup onto the motor shaft in the correct orientation, and ensuring it passes cleanly through the RPM sensor fork without rubbing. No programming is required after replacement on models designed for this part, but compatibility should be confirmed against the opener’s parts list or service manual before purchase, as newer DC motor or Security+ 2.0 units may use different encoders. For residential or light commercial applications, this genuine-style replacement helps maintain accurate motor speed sensing and safe, reliable door movement when paired with a functional RPM sensor and gear assembly.