Ricoh D124 Detailed Descriptions Manual page 26

 The air release solenoid (12) purges air from the ink sub tanks. This single
solenoid services all the print head sub tanks.
 The head lift motor (13) on the right side of the main unit frame (controlled by two
lift sensors housed in the carriage unit) raises and lowers the carriage unit to
adjust the gap between the paper and print heads for different thickness of paper.
This prevents the print heads from abrading the surface of thick paper during
printing.
D124 20 Detailed Descriptions