HP 2500C Series - Manual (Page 137)

Functional Overview 6-17
Paper Paths and Components
To achieve linefeed of less than 1/300 inch, the spacing between counts will have to be
extrapolated with the help of the HP HEDS 9730 series incremental encoder module.
With this combination, the smallest linefeed increment of 1/2400 inch will be possible.
Due to torque and throughput consideration, a gear ratio of 15 : 1 is used. This is
achieved in two stages of 3.75 and 4. Spur gears with AGMA quality standard 10 were
selected to ensure good accuracy and to help minimize servo-control problems. Also,
pressure angle of 14.5
°
was used to reduce transmission noise.