Ricoh D131 Service Manual page 1509

Details
FM1 Z-Folding
In Fold Method 1 (FM1):
The leading edge of the paper feeds into the nip of fold rollers
The paper is stopped by Fold Stopper 2. The paper flexes toward the nip of fold rollers
and which performs the first fold.
Next, the paper is stopped by Fold Stopper 3. The paper flexes toward the nip of fold
rollers and which performs the second fold and feeds the paper into the exit path.
Fold Stopper 1 is not used.
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