ABB AV1 Operating Instructions Manual page 120

TYPE AV1 PNEUMATIC POSITION TRANSMITTER
CALIBRATION
D - 4
15. Repeat Steps 8 through 14 until the positioner is calibrated.
NOTE: Moving the span adjustment assembly toward the valve
body provides a longer actuator stroke for a given signal change
(i.e., increases the range of travel for the cam follower arm).
Moving the span adjustment bearing away from the valve body
causes the opposite to occur (i.e., decreases the range of travel
for the cam follower arm).