The LiftMaster 41A5585-1 Gear and Sprocket Assembly is a genuine OEM replacement for select LiftMaster, Chamberlain, and Craftsman chain-drive garage door openers manufactured by The Chamberlain Group. Installed at the top of the motor head, this assembly transfers motor power to the drive chain that moves the trolley. Replacing a worn or broken top sprocket/shaft assembly restores smooth lifting performance, reduces chain slippage and grinding noises, and helps prevent further drivetrain damage. This part is commonly used in residential chain-drive applications and is not intended for belt-drive, screw-drive, or wall-mount/jackshaft operators. The 41A5585-1 is also known by the later revision 41A5585-1C on some documentation and packaging.
Designed for AC-motor chain-drive operators built by Chamberlain Group, this assembly is engineered to fit select compatible LiftMaster, Chamberlain, and Sears Craftsman units. For best results, match by part number in your owner’s manual or on the opener’s parts label. If the opener’s large internal drive gear is worn, the separate gear repair kit (commonly listed as 41A2817) may also be required in addition to this top assembly. Basic installation involves disconnecting power, relieving chain tension, removing the opener cover, swapping the original top shaft/sprocket assembly, then re-tensioning the chain and verifying travel and force settings per the manufacturer’s instructions. Always disconnect power and secure the door before servicing, and recheck safety reversal and photo-eye operation after completion.
Compatible with LiftMaster 2575, 3275, 3575 and 3575S models