1. Mechanical adjustment mainly refers to the adjustment to the length of the mechanism tumbler, which enables the tumbler of the electric actuator to rotate 90 degrees counterclockwise, or enables the adjustment mechanism to travel the whole stroke from the "fully-closing" to "fully-opening"  when the piston rod of the pneumatic actuator moves from the lowest position to the highest position.

2. When the adjustment mechanism travels from "fully-closing" to "fully-opening", but the tumbler of the actuator has already rotated more than 90 degrees, it is required to move the pinhole of the adjustment mechanism inward, and namely the arm length is shortened. If the tumbler of the actuator cannot rotate to 90 degrees, the pinhole of the tumbler of the adjustment mechanism shall be moved outward, namely the length of the tumbler is increased.