Ricoh D131 Service Manual page 1493

Details
2.2.2 PRE-STACKING
Up to three sheets of paper can be pre-stacked for folding.
The left illustration shows the parts that operate during pre-stacking.
The paper enters the machine [A].
The lower entrance junction gate [B] opens and guides the paper to the TE stop pawl
[C].
The paper pushes the TE stop pawl aside so it can pass.
D454/D615 100 SM