The LiftMaster 41A2822A Interrupter Cup – Small is an OEM replacement encoder wheel used on select LiftMaster, Chamberlain, and Craftsman residential garage door openers that employ an optical RPM sensor. Mounted on the motor shaft, this slotted cup passes through the RPM sensor to provide motor speed feedback to the control board. Replacing a cracked or deformed cup restores accurate speed detection and can resolve symptoms such as the motor starting and stopping abruptly or the opener indicating an RPM/speed-sensor fault. This part is commonly referenced as an interrupter wheel, tachometer cup, or encoder cup, and is intended for units designed to use the “small” cup variant identified by part number 41A2822A.
Installation typically involves disconnecting power, removing the opener cover, accessing the motor assembly, and pressing the new cup onto the motor shaft so its slots are centered within the RPM sensor gap without rubbing. No reprogramming is usually required; follow your opener’s manual if travel or force adjustments are needed afterward. This listing is for the cup only; the RPM sensor is a separate component. For best compatibility results, match 41A2822A to the number in your opener’s parts manual or verify by comparing the existing cup on the motor shaft, as not all LiftMaster/Chamberlain/Craftsman models use the same interrupter cup.