LiftMaster

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• LiftMaster 841LM Automatic Garage Door Lock

  The LiftMaster 841LM Automatic Garage Door Lock adds an extra layer of physical security to compatible garage door opener systems. When the garage door closes, the lock automatically drives a deadbolt through the garage door track to help prevent the door from being forced upward.

  The lock works directly with a compatible LiftMaster opener, automatically locking when the door closes and unlocking before the opener raises the door. No separate remote control or manual locking step is required during normal operation.

  Product Features

  • Genuine LiftMaster automatic garage door lock
  • Model: 841LM
  • Automatically locks when the garage door closes
  • Automatically unlocks before the opener opens the door
  • Powered deadbolt extends through the garage door track
  • Helps resist forced lifting of the garage door
  • Operates together with a compatible LiftMaster opener
  • Audible engagement provides confirmation that the lock has activated
  • Suitable as a replacement lock or add-on security accessory
  • One lock provides a single locking point
  • Two compatible locks can create a two-point locking system

  How the Automatic Lock Works

  The lock mounts beside the garage door track. When the opener completes its closing cycle, the deadbolt extends through an opening in the track and prevents the door rollers from traveling upward.

  When the opener receives an opening command, it retracts the deadbolt before moving the garage door. This automatic sequence eliminates the risk of operating the opener while a manual slide lock is still engaged.

  Confirmed Compatibility

  The LiftMaster 841LM is sold separately for compatible automatic-lock-capable LiftMaster opener models, including:

  • WLED
  • 8550WLB
  • 8360WLB
  • 8580WLB
  • 8587WL

  It is also used with certain compatible LiftMaster wall-mount, residential, and light-commercial operators specifically equipped with automatic-lock connection terminals.

  Compatibility must be confirmed by checking the opener model number, owner’s manual, wiring terminals, and replacement-parts information. The opener must be specifically designed to control the 841LM lock.

  This lock cannot be added to every LiftMaster, Chamberlain, or Craftsman garage door opener.

  Important Model Identification

  Some opener models were manufactured in both automatic-lock-compatible and non-compatible versions. Compatible units may have:

  • Dedicated lock connection terminals
  • An automatic-lock symbol on the opener housing
  • An “L” designation in the opener model number
  • Automatic-lock compatibility stated in the owner’s manual

  Do not order based only on the opener’s general series name.

  Two-Lock Applications

  A second 841LM lock may be installed on certain compatible systems to provide locking points on both sides of the garage door.

  LiftMaster states that properly configured two-lock systems have been engineered and tested for certain hurricane-ready applications. However, the lock does not replace a required center post, bracing system, or other wind-load hardware specified by the garage door manufacturer.

  Package Contents

  • One LiftMaster 841LM automatic garage door lock
  • Connection wire
  • Installation hardware

  Only one lock is included. A second lock, compatible opener, garage door track, and other accessories are sold separately unless specifically stated.

  Installation Requirements

  Before installation, confirm that:

  • The garage door opener supports the 841LM
  • The selected mounting area has adequate clearance
  • The garage door track is suitable for the lock deadbolt
  • The door is properly balanced and operating smoothly
  • The lock can fully extend without contacting a roller, hinge, cable, or other hardware
  • The wiring can be safely routed between the lock and opener

  The track may require a properly positioned opening for the deadbolt, depending on the existing installation.

  Installation and Safety

  Disconnect electrical power and battery power from the garage door opener before installing or servicing the lock.

  The lock must be positioned and aligned correctly. A misaligned deadbolt may prevent the garage door from opening, damage the track, or place unnecessary strain on the opener.

  Installation by a trained garage door technician is recommended.

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  LiftMaster 841LM Automatic Garage Door Lock

   LiftMaster 841LM automatic powered deadbolt lock for compatible garage door openers. Automatically locks the door closed and unlocks before opening.