Lexmark T650n Service Manual page 257

4062-XXX
The pick arm assembly (autocompensator) is a paper pick device that generates its own normal force. This
force generation is inherent in the fundamental design of the pick arm. If light media is used, it picks very
gently. If a heavy media is used, it picks very aggressively. No customer adjustments are necessary, therefore
no special trays are needed for card stock or labels. The gearing in the arm is designed so the input torque
from the motor produces a movement about the pivot of the arm. This movement produces a downward force
at the pick rolls. The friction between the pick roll and the paper produces a frictional locking condition. If the
paper is physically held and not allowed to feed, then the motor stalls. Slippage between the roll and the paper
is theoretically impossible. When the motor is energized, the pick rolls are driven down into the stack,
increasing the normal force and drive force until the bending strength of the paper is overcome and the paper
bends and moves up the wear strip.
3-55
Diagnostic aids