what is advanced variable backcheck do


AVB stands for Advanced Variable Backcheck. It is a cylinder option when ordering a 4111 closer (without an ST) that allows backcheck to start at about 45 degrees instead of the normal 75 degrees...
AVB, Cylinder Function, 4110 Series Closer
Advanced Variable Backcheck
The valve on the back of a 4041/4040XP closer is a "Back Check Selector Valve" that needs to be turned in on "Parallel Arm" mount applications ONLY. If a 4041/4040XP closer mounted "Top Jamb", or "...
  How to:  What are the steps to adjust a door closer?   Facts: All LCN and FALCON door closers will have 3 regulating valves and a spring adjustment.  All cl...
Closer Adjustment, Door Control
Valve used to provide proper backcheck location for 4040XP and 4050A parallel arm mounting