There are 4 types of bottom brackets used. Each of these brackets is designed to carry the bottom roller on the door. The most common is the standard bottom bracket. Be aware that in residential applications, this will usually ship as a connected left/right pair. The person installing the door will need to snap them apart prior to install.
The lift cables are attached to the bottom bracket with either a stud on the standard duty bottom bracket, or using a clevis pin and cotter pin also called a split pin. A pull rope can be attached to the bottom bracket to assist a homeowner to close a manually operated door when in the upright position. (Drawing of bottom bracket installed on panel with lift cable attached pictured on the left. Clevis pin and cotter pin pictured in the center, pull rope pictured to the right)
Bottom brackets for doors with low headroom track are designed to allow the cable to run on the outside of the track.
The heavy duty double end stile bottom bracket is for doors weighing over 1500 pounds. Commercial bottom brackets are affixed to the door using red-headed tek screws to indicate caution. The lift cables are attached to the bottom bracket and are under extreme tension. Removing the screws while the springs are wound could cause injury or death.
While residential doors do not always have red-headed tek screws to indicate caution, these bottom brackets can also cause injury or death if removed while springs are still under tension.
Additional information on new commercial bottom bracket design is explained in Tech's Corner: Commercial Bottom Brackets BB-2000
Additional information on Low Headroom Bottom Brackets are explained in https://freshdesk.clopay.com/en/support/solutions/articles/67000713577-tech-s-corner-low-headroom-bottom-brackets-all-types
Reviewed: Sarah Cupp
Date: 12/16/22